【转载】SpringMVC学习笔记
转载于：SpringMVC笔记
SpringMVC
1.SpringMVC概述
MVC：
-
Model（模型）： 数据模型，提供要展示的数据，：Value Object（数据Dao） 和 服务层（行为Service），提供数据和业务。
-
View（视图）： 负责进行模型的展示，即用户界面
-
Controller（控制器）： 调度员，接收用户请求，委托给模型进行处理（状态改变），处理完毕后把返回的模型数据返回给视图，由视图负责展示。
SpringMVC的特点：
-
Spring为展现层提供的基于MVC设计理念的Web框架
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SpirngMVC通过一套MVC注解，让POJO成为处理请求的控制器，而无须实现任何接口
-
支持REST风格的URL请求
-
采用了松散耦合可拔插组件结构，扩展性和灵活性
2. HelloWorld
1. 导入依赖
spring-webmvc的maven依赖
<dependencies>
<!-- SpringWeb基础包-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>4.0.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>4.0.0.RELEASE</version>
</dependency>
<!-- 核心包-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.0.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>4.0.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>4.0.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-expression</artifactId>
<version>4.0.0.RELEASE</version>
</dependency>
<!-- 日志包-->
<dependency>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
<version>1.1.3</version>
</dependency>
<!-- 注解支持包-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>4.0.0.RELEASE</version>
</dependency>
</dependencies></pre>
2. 配置web.xml ， 注册DispatcherServlet
DispatcherServlet：前端控制器，负责请求分发。
要绑定Spring的配置文件
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<!--注册DispatcherServlet,请求分发器（前端控制器）-->
<servlet>
<servlet-name>springDispatcherServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!--绑定Spring配置文件-->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springmvc-config.xml</param-value>
</init-param>
<!--启动级别为1，即服务器启动后就启动-->
<!--值越小优先级越高，越先创建对象-->
<load-on-startup>1</load-on-startup>
</servlet>
<!-- / 拦截所有的请求；（不包括.jsp，jsp由Tomcat来处理），
覆盖了父类的DispatcherServlet的pattern，静态资源被拦截。-->
<!-- *.jsp 拦截jsp请求，覆盖了父类的JspServlet-->
<!-- /* 拦截所有的请求；（包括.jsp，一旦拦截jsp页面就不能显示了）-->
<servlet-mapping>
<servlet-name>springDispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
3. 导入Spring配置文件
Spring的配置文件Springmvc-config.xml。
-
开启了包扫描，让指定包下的注解生效，由IOC容器统一管理
-
配置了视图解析器InternalResourceViewResolver，这里可以设置前缀和后缀，拼接视图名字
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<!--开启包扫描,让指定包下的注解生效,由IOC容器统一管理-->
<context:component-scan base-package="com.xiao.controller"/>
<!--配置视图解析器，拼接视图名字，找到对应的视图-->
<bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<!--前缀-->
<property name="prefix" value="/WEB-INF/page/"/>
<!--后缀-->
<property name="suffix" value=".jsp"/>
</bean>
</beans>
4. 编写controller层
HelloController类：
-
@Controller：告诉Spirng这是一个控制器，交给IOC容器管理
-
@RequestMapping("/hello01")：/ 表示项目地址，当请求项目中的hello01时，返回一个/WEB-INF/page/success.jsp页面给前端
@Controller
public class HelloController {
@RequestMapping("/hello01")
public String toSuccess(){
System.out.println("请求成功页面");
return "success";
}
@RequestMapping("/hello02")
public String toError() {
System.out.println("请求错误页面");
return "error";
}
}
5. 编写跳转的jsp页面
项目首页 index.jsp，两个超链接，分别发出hello01和hello02的请求
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<a href="hello01">点这里去成功页面</a>
<a href="hello02">点这里去失败页面</a>
</body>
</html>
成功页面success.jsp和失败页面error.jsp，要注意文件的路径/WEB-INF/page/…jsp，与上面的保持一致
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>成功页面</title>
</head>
<body>
<h1>这里是成功页面</h1>
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>错误页面</title>
</head>
<body>
<h1>这里是错误页面</h1>
</body>
</html>
6) 访问
启动项目：
点击去成功页面，可以看到发出了/hello01请求，页面转发到/WEB-INF/page/success.jsp，控制台输出了请求成功页面。
3. Url请求
3.1 运行流程
-
客户端点击链接发送请求：http://localhost:8080/hello01；
-
来到tomcat服务器；
-
SpringMVC的前端控制器收到所有请求；
-
看请求地址和@RequestMapping标注的哪个匹配，来找到底使用哪个类的哪个方法来处理；
-
前端控制器找到目标处理器类和目标方法，直接利用反射执行目标方法；
-
方法执行完后有一个返回值，SpringMVC认为这个返回值就是要去的页面地址；
-
拿到方法返回值后，视图解析器进行拼串得到完整的页面地址
-
得到页面地址，前端控制器帮我们转发到页面
3.2 url映射
RequestMapping
01 标注在方法上
告诉SpringMVC这个方法用来处理什么请求。
@RequestMapping("/hello01")中的 /可以省略，就是默认从当前项目下开始。
02 标注在类上
表示为当前类中的所有方法的请求地址，指定一个基准路径。toSuccess()方法处理的请求路径是/haha/hello01。
@Controller
@RequestMapping("/haha")
public class HelloController {
@RequestMapping(value = "/hello01")
public String toSuccess(){
System.out.println("请求成功页面");
return "success";
}
}
03 规定请求方式
method属性规定请求方式，默认是所求请求方式都行。method = RequestMethod.GET，method = RequestMethod.POST。
如果方法不匹配会报：HTTP Status 405 错误 – 方法不被允许
@RequestMapping(value = "/hello01",method = RequestMethod.GET)
public String toSuccess(){
System.out.println("请求成功页面");
return "success";
}
组合用法
-
@GetMapping 等价于 @RequestMapping(method =RequestMethod.GET)
-
@PostMapping
-
@PutMapping
-
@DeleteMapping
-
@PatchMapping
04 规定请求参数
params属性规定请求参数。会造成错误：HTTP Status 400 – 错误的请求
不携带该参数，表示参数值为null；携带了不给值表示参数值是空串
//必须携带username参数
@RequestMapping(value = "/hello03",params ={"username"})
//必须不携带username参数
@RequestMapping(value = "/hello03",params ={"！username"})
//必须携带username参数，且值必须为123
@RequestMapping(value = "/hello03",params ={"username=123"})
//username参数值必须不为123，不携带或者携带了不是123都行
@RequestMapping(value = "/hello03",params ={"username=！123"})
//username参数值必须不为123，不携带password，携带page
@RequestMapping(value = "/hello03",params ={"username=！123","page","!password"})
05 规定请求头
headers属性规定请求头。其中User-Agent：浏览器信息
谷歌浏览器：User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.3
06 Ant风格URL
URL地址可以写模糊的通配符，模糊和精确多个匹配情况下精确优先。
？：替代任意一个字符
@RequestMapping( "/hello0?") /
*：替代任意多个字符或一层路径
@RequestMapping( "/hello0*") //任意多个字符 @RequestMapping( "/a/*/hello01") //一层路径
@RequestMapping(value = "/test/*/a")
public String myMethodTest01() {
System.out.println("post01");
return "success";
}
// test/[^\/]+/b ->post01
// /test/*/b ->post02
@RequestMapping(value = "/test/**/a")
public String myMethodTest02() {
System.out.println("post02");
return "success";
}
**：替代任意多层路径
@RequestMapping( "/a/**/hello01") //任意多层路径
07 PathVariable
可以用/test/{paramsName1}/{paramsName2}来获取Url上传的参数值
//获取到{id}占位符，占位符可以在任意路径地方写{变量名}
//@PathVariable("id") 获取请求路径哪个占位符的值
@RequestMapping(value = "/test/{id}", method = RequestMethod.GET)
public String myMethodTest03(@PathVariable("id") String id) {
System.out.println("路径上占位符"+id);
return "success"；
}
3.3 Spring配置文件的默认位置
默认位置是 /WEB-INF/xxx-servlet.xml，其中xxx是自己在web.xml文件中配置的servlet-name属性。
例如：
dispatcherServlet-servlet.xml
当然也可以手动指定文件位置。
<servlet> <servlet-name>dispatcherServlet</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet>
3.5 url-pattern
/ 拦截所有的请求，不拦截jsp
/* 拦截所有的请求，包括*.jsp，一旦拦截jsp页面就不能显示了。. jsp是tomcat处理的事情
看Tomcat的配置文件web.xml中，有DefaultServlet和JspServlet，
-
DefaultServlet是Tomcat中处理静态资源的，Tomcat会在服务器下找到这个资源并返回。如果我们自己配置
url-pattern=/，相当于禁用了Tomcat服务器中的DefaultServlet，这样如果请求静态资源，就会去找前端控制器找@RequestMapping，这样静态资源就不能访问了。解决办法：<!-- 告诉Spring MVC自己映射的请求就自己处理，不能处理的请求直接交给tomcat --> <mvc:default-servlet-handler /> <!--开启MVC注解驱动模式，保证动态请求和静态请求都能访问--> <mvc:annotation-driven/>
4. REST风格
4.1 概述
REST就是一个资源定位及资源操作的风格。不是标准也不是协议，只是一种风格。基于这个风格设计的软件可以更简洁，更有层次，更易于实现缓存等机制。其强调HTTP应当以资源为中心，并且规范了URI的风格；规范了HTTP请求动作（GET/PUT/POST/DELETE/HEAD/OPTIONS）的使用，具有对应的语义。
-
资源（Resource）：网络上的一个实体，每种资源对应一个特定的URI，即URI为每个资源的独一无二的识别符；
-
表现层（Representation）：把资源具体呈现出来的形式，叫做它的表现层。比如txt、HTML、XML、JSON格式等；
-
状态转化（State Transfer）：每发出一个请求，就代表一次客户端和服务器的一次交互过程。GET用来获取资源，POST用来新建资源，PUT用来更新资源，DELETE用来删除资源。
在参数上使用 @PathVariable 注解，可以获取到请求路径上的值，也可以写多个
@RequestMapping(value = "/hello04/username/{id}")
public String test2(@PathVariable("id") int id){
System.out.println(id);
return "success";
}
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4.2 页面上发出PUT请求
对一个资源的增删改查用请求方式来区分：
-
/book/1 GET：查询1号图书
-
/book/1 DELETE：删除1号图书
-
/book/1 PUT：修改1号图书
-
/book POST：新增图书
页面上只能发出GET请求和POST请求。将POST请求转化为put或者delete请求的步骤：
-
把前端发送方式改为post 。
-
在web.xml中配置一个filter：HiddenHttpMethodFilter过滤器
-
必须携带一个键值对，key=_method, value=put或者delete
<!--这个过滤器的作用 ：就是将post请求转化为put或者delete请求--> <filter> <filter-name>HiddenHttpMethodFilter</filter-name> <filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class> </filter> <filter-mapping> <filter-name>HiddenHttpMethodFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <form action="hello03" method="post"> <input type="hidden" name="_method" value="delete"> <input type="submit" name="提交"> </form>
注意
高版本Tomcat会出现问题：JSPs only permit GET POST or HEAD，在页面上加上异常处理即可
<%@ page contentType="text/html;charset=UTF-8" language="java" isErrorPage="true" %> 1
5 请求参数处理
5.1 传入参数
1. 如果提交的参数名称和处理方法的参数名一致，则无需处理，直接使用
提交数据 : http://localhost:8080/hello05?username=zhangsan，控制台会输出zhangsan
@RequestMapping("/hello05")
public String test03(String username) {
System.out.println(username);
return "success";
}
2. 提交的参数名称和处理方法的参数名不一致，使用@RequestParam注解
注解@RequestParam可以获取请求参数，默认必须携带该参数，也可以指定required=false，和没携带情况下的默认值defaultValue
@RequestMapping(value = "/hello03",params ={"username"})
public String test03(@RequestParam("user")String username
等价于 username = request.getParameter("user"))
传入网址为："handle01?user=aaa"
@RequestMapping("/hello05")
public String test03(@RequestParam(value = "username",required = false, defaultValue ="hehe" ) String name) {
System.out.println(name);
return "success";
}
//比较
@ReqquestParam("user02") 获取问号后面占位符
@PathVariable("user01") 获取路径占位符 /book/{user01}?user02=admin
还有另外两个注解：
-
@RequestHeader：获取请求头中的信息，比如User-Agent：浏览器信息@RequestMapping("/hello05") public String test03(@RequestHeader("User-Agent" ) String name) { System.out.println(name); return "success"; } -
@CookieValue：获取某个cookie的值@RequestMapping("/hello05") public String test03(@CookieValue("JSESSIONID" ) String name) { System.out.println(name); return "success"; } 等价于 Cookie[] cookies = request.getCookies(); for(Cookie c:cookies){ if(c.getName().equals("JSESSIONID")){ String cookievalue = c.getValue(); } }
5.2 传入一个对象
传入POJO，SpringMVC会自动封装，提交的表单域参数必须和对象的属性名一致，否则就是null，请求没有携带的字段，值也会是null。同时也还可以级联封装。
新建两个对象User和Address：
public class User {
private String username;
private Integer age;
private Address address;
//....
}
123456
public class Address {
private String name;
private Integer num;
//....
}
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前端请求：
<form action="hello06" method="post"> 姓名： <input type="text" name="username"> <br> 年龄： <input type="text" name="age"><br> 地址名：<input type="text" name="address.name"><br> 地址编号：<input type="text" name="address.num"><br> <input type="submit" name="提交"> </form>
后端通过对象名也能拿到对象的值，没有对应的值则为null
@RequestMapping("/hello06")
public String test03(User user) {
System.out.println(user);
return "success";
}
5.3 传入原生ServletAPI
处理方法还可以传入原生的ServletAPI：
@RequestMapping("/hello07")
public String test04(HttpServletRequest request, HttpSession session) {
session.setAttribute("sessionParam","我是session域中的值");
request.setAttribute("reqParam","我是request域中的值");
return "success";
}
通过EL表达式获取到值，${requestScope.reqParam}：
<%@ page contentType="text/html;charset=UTF-8" language="java" isErrorPage="true" %>
<html>
<head>
<title>成功页面</title>
</head>
<body>
<h1>这里是成功页面</h1>
${requestScope.reqParam}
${sessionScope.sessionParam}
</body>
</html>
5.4 乱码问题
一定要放在在其他Filter前面。
<filter> <filter-name>encoding</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <!--解决请求乱码--> <init-param> <param-name>encoding</param-name> <param-value>utf-8</param-value> </init-param> <!--解决响应乱码--> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>encoding</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <!--在Tomcat的server.xml中的8080处 URLEncoding="UTF-8"-->
6. 数据输出
6.1 Map、Model、ModelMap
实际上都是调用的 BindingAwareModelMap(隐含模型)，将数据放在请求域(requestScope)中进行转发，用EL表达式可以取出对应的值。
/** * SpringMVC除过在方法上传入原生的request和session外还能怎么样把数据带给页面 * * 1）、可以在方法处传入Map、或者Model或者ModelMap。 * 给这些参数里面保存的所有数据都会放在请求域中。可以在页面获取 * 关系： * Map，Model，ModelMap：最终都是BindingAwareModelMap在工作； * 相当于给BindingAwareModelMap中保存的东西都会被放在请求域中； * * Map(interface(jdk)) Model(interface(spring)) * || // * || // * \/ // * ModelMap(class) // * \\ // * \\ // * ExtendedModelMap * || * \/ * BindingAwareModelMap * * 2）、方法的返回值可以变为ModelAndView类型； * 既包含视图信息（页面地址）也包含模型数据（给页面带的数据）； * 而且数据是放在请求域中； * request、session、application； * * * @author lfy * */
-
Map
@RequestMapping("/Api2")
public String api2(Map<String,Object> map){
map.put("msg","hello");
return "map";
}
-
Model
@RequestMapping("/Api3")
public String api3(Model model){
model.addAttribute("msg","hello2");
return "map";
}
-
ModelMap
@RequestMapping("/Api4")
public String api4(ModelMap modelMap){
modelMap.addAttribute("msg","hello3");
return "map";
}
都放在请求域request中，类型都是BindingAwareModelMap，相当于放在BindingAwareModelMap的请求都放在请求域中
map页面：
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
pageScope: ${pageScope.msg}
requestScope : ${requestScope.msg}
sessionScope: ${sessionScope.msg}
applicationScope: ${applicationScope.msg}
</body>
</html>
【补充】jsp的4个作用域 pageScope、requestScope、sessionScope、applicationScope的区别：
-
page指当前页面有效。在一个jsp页面里有效
-
request 指在一次请求的全过程中有效，即从http请求到服务器处理结束，返回响应的整个过程，存放在HttpServletRequest对象中。在这个过程中可以使用forward方式跳转多个jsp。在这些页面里都可以使用这个变量。
-
Session是用户全局变量，在整个会话期间都有效。只要页面不关闭就一直有效（或者直到用户一直未活动导致会话过期，默认session过期时间为30分钟，或调用HttpSession的invalidate()方法）。存放在HttpSession对象中
-
application是程序全局变量，对每个用户每个页面都有效。存放在ServletContext对象中。它的存活时间是最长的，如果不进行手工删除，它们就一直可以使用
6.2 ModelAndView
方法的返回值变为ModelAndView，返回一个模型视图对象ModerAndView， 既包含视图信息(页面地址)，也包含模型数据(给页面带的数据)
@RequestMapping("/hello04")
public ModelAndView test04 (){
//新建一个模型视图对象，也可以直接传入名字
ModelAndView mv = new ModelAndView();
//封装要显示到视图中的数据
//相当于req.setAttribute("msg",HelloWorld!);
mv.addObject("msg","HelloWorld!");
//设置视图的名字，相当于之前的return "success"; WebContent/WEB-INF/pages/success.jsp
mv.setViewName("success");
return mv;
}
6.3 @SessionAttributes
给Session域中携带数据使用注解@SessionAttributes，只能标在类上，value属性指定key，type可以指定保存类型。这个注解会引发异常一般不用，就用原生API
@SessionAttributes(value = "msg")：表示给BindingAwareModelMap中保存key为msg的数据时，在session中也保存一份；
@SessionAttributes(types = {String.class})：表示只要保存String类型的数据时，给session中也放一份。
//表示给BindingAwareModelMap中保存key为msg的数据时，在session中也保存一份
@SessionAttributes(value = "msg")
@Controller
public class outputController {
@RequestMapping("/hello01")
public String test01 (Map<String,Object> map){
map.put("msg","HelloWorld!");
return "success";
}
}
6.4 @ModelAttribute
ModelAttribute：
使用场景：
1）、页面：form提交更新
2）、dao：全字段更新。没带的字段会在数据库中更新为null；
/**
* 测试ModelAttribute注解；
* 使用场景：书城的图书修改为例；
* 1）页面端；
* 显示要修改的图书的信息，图书的所有字段都在
* 2）servlet收到修改请求，调用dao；
* String sql="update bs_book set title=?,
* author=?,price=?,
* sales=?,stock=?,img_path=?
* where id=?";
* 3）实际场景？
* 并不是全字段修改；只会修改部分字段，以修改用户信息为例；
* username password address;
* 1）、不修改的字段可以在页面进行展示但是不要提供修改输入框；
* 2）、为了简单，Controller直接在参数位置来写Book对象
* 3）、SpringMVC为我们自动封装book；（没有带的值是null）
* 4）、如果接下来调用了一个全字段更新的dao操作；会将其他的字段可能变为null；
* sql = "update bs_book set"
* if(book.getBookName()){
* sql +="bookName=?,"
* }
* if(book.getPrice()){
* sql +="price=?"
* }
*
* 4）、如何能保证全字段更新的时候，只更新了页面携带的数据；
* 1）、修改dao；代价大？
* 2）、Book对象是如何封装的？
* 1）、SpringMVC创建一个book对象，每个属性都有默认值，bookName就是null；
* 1、让SpringMVC别创建book对象，直接从数据库中先取出一个id=100的book对象的信息
* 2、Book [id=100, bookName=西游记, author=张三, stock=12, sales=32, price=98.98]
*
* 2）、将请求中所有与book对应的属性一一设置过来；
* 3、使用刚才从数据库取出的book对象，给它 的里面设置值；（请求参数带了哪些值就覆盖之前的值）
* 4、带了的字段就改为携带的值，没带的字段就保持之前的值
* 3）、调用全字段更新就有问题；
* 5、将之前从数据库中查到的对象，并且封装了请求参数的对象。进行保存；
*
* @author lfy
*/
方法入参标注该注解后，入参的对象就会放到数据模型中，会提前于控制方法先执行，并发方法允许的结果放在隐含模型中。
处理这样的场景：
前端传来数据，SpringMVC自动封装成对象，实际上是创建了一个对象，每个属性都有默认值，然后将请求参数中对应是属性设置过来，但是如果没有的值将会是null，如果拿着这个数据去更新数据库，会造成其他字段也变为null。因此希望使用@ModelAttribute，会在目标方法执行前先做一些处理
@ModelAttribute
public void myModelAttribute(ModelMap modelMap){
System.out.println("modelAttribute方法执行了");
//提前做一些处理
User user = new User("zhangsan",20);
//保存一个数据到BindingAwareModelMap中，目标方法可以从中取出来
modelMap.addAttribute("user",user);
}
@RequestMapping("/hello05")
public void test05(@ModelAttribute("user") User user){
System.out.println("目标方法执行了");
//在参数上加上@ModelAttribute注解，可以拿到提前存入的数据
System.out.println(user);
}
6.5 @ResponseBody
在控制器类中，在方法上使用@ResponseBody注解可以不走视图解析器，如果返回值是字符串，那么直接将字符串写到客户端；如果是一个对象，会将对象转化为JSON串，然后写到客户端。
或者在类上加 @RestController注解，可以让类中的所有方法都不走视图解析器，直接返回JSON字符串
7. 视图源码执行流程
7.0 SpringMVC的九大组件
-
multipartResolver：文件上传解析器
-
localeResolver：区域信息解析器，和国际化有关
-
themeResolver：主题解析器
-
handlerMappings：handler的映射器
-
handlerAdapters：handler的适配器
-
handlerExceptionResolvers：异常解析功能
-
viewNameTranslator：请求到视图名的转换器
-
flashMapManager：SpringMVC中允许重定向携带数据的功能
-
viewResolvers：视图解析器
/** 文件上传解析器*/
private MultipartResolver multipartResolver;
/** 区域信息解析器；和国际化有关 */
private LocaleResolver localeResolver;
/** 主题解析器；强大的主题效果更换 */
private ThemeResolver themeResolver;
/** Handler映射信息；HandlerMapping */
private List<HandlerMapping> handlerMappings;
/** Handler的适配器 */
private List<HandlerAdapter> handlerAdapters;
/** SpringMVC强大的异常解析功能；异常解析器 */
private List<HandlerExceptionResolver> handlerExceptionResolvers;
/** */
private RequestToViewNameTranslator viewNameTranslator;
/** FlashMap+Manager：SpringMVC中运行重定向携带数据的功能 */
private FlashMapManager flashMapManager;
/** 视图解析器； */
private List<ViewResolver> viewResolvers;
onRefresh()->initStrategies() DispatcherServlet中：
protected void initStrategies(ApplicationContext context) {
initMultipartResolver(context);
initLocaleResolver(context);
initThemeResolver(context);
initHandlerMappings(context);
initHandlerAdapters(context);
initHandlerExceptionResolvers(context);
initRequestToViewNameTranslator(context);
initViewResolvers(context);
initFlashMapManager(context);
}
例：初始化HandlerMapping
private void initHandlerMappings(ApplicationContext context) {
this.handlerMappings = null;
if (this.detectAllHandlerMappings) {
// Find all HandlerMappings in the ApplicationContext, including ancestor contexts.
Map<String, HandlerMapping> matchingBeans =
BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerMapping.class, true, false);
if (!matchingBeans.isEmpty()) {
this.handlerMappings = new ArrayList<HandlerMapping>(matchingBeans.values());
// We keep HandlerMappings in sorted order.
OrderComparator.sort(this.handlerMappings);
}
}
else {
try {
HandlerMapping hm = context.getBean(HANDLER_MAPPING_BEAN_NAME, HandlerMapping.class);
this.handlerMappings = Collections.singletonList(hm);
}
catch (NoSuchBeanDefinitionException ex) {
// Ignore, we'll add a default HandlerMapping later.
}
}
// Ensure we have at least one HandlerMapping, by registering
// a default HandlerMapping if no other mappings are found.
if (this.handlerMappings == null) {
this.handlerMappings = getDefaultStrategies(context, HandlerMapping.class);
if (logger.isDebugEnabled()) {
logger.debug("No HandlerMappings found in servlet '" + getServletName() + "': using default");
}
}
}</pre>
组件的初始化： 有些组件在容器中是使用类型找的，有些组件是使用id找的；
去容器中找这个组件，如果没有找到就用默认的配置；
7.1 前端控制器DisatcherServlet
7.2 SpringMVC执行流程
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpServletRequest processedRequest = request;
HandlerExecutionChain mappedHandler = null;
boolean multipartRequestParsed = false;
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
try {
ModelAndView mv = null;
Exception dispatchException = null;
try {
//1、检查是否文件上传请求
processedRequest = checkMultipart(request);
multipartRequestParsed = processedRequest != request;
// Determine handler for the current request.
//2、根据当前的请求地址找到那个类能来处理；
mappedHandler = getHandler(processedRequest);
//3、如果没有找到哪个处理器（控制器）能处理这个请求就404，或者抛异常
if (mappedHandler == null || mappedHandler.getHandler() == null) {
noHandlerFound(processedRequest, response);
return;
}
// Determine handler adapter for the current request.
//4、拿到能执行这个类的所有方法的适配器；（反射工AnnotationMethodHandlerAdapter）
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
// Process last-modified header, if supported by the handler.
String method = request.getMethod();
boolean isGet = "GET".equals(method);
if (isGet || "HEAD".equals(method)) {
long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
if (logger.isDebugEnabled()) {
String requestUri = urlPathHelper.getRequestUri(request);
logger.debug("Last-Modified value for [" + requestUri + "] is: " + lastModified);
}
if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
return;
}
}
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}
try {
// Actually invoke the handler.处理（控制）器的方法被调用
//控制器（Controller），处理器（Handler）
//5、适配器来执行目标方法；
//将目标方法执行完成后的返回值作为视图名，设置保存到ModelAndView中
//目标方法无论怎么写，最终适配器执行完成以后都会将执行后的信息封装成ModelAndView
mv = ha.handle(processedRequest,response,mappedHandler.getHandler());
} finally {
if (asyncManager.isConcurrentHandlingStarted()) {
return;
}
}
applyDefaultViewName(request, mv);//如果没有视图名设置一个默认的视图名；
mappedHandler.applyPostHandle(processedRequest, response, mv);
} catch (Exception ex) {
dispatchException = ex;
}
//转发到目标页面；
//6、根据方法最终执行完成后封装的ModelAndView；
//转发到对应页面，而且ModelAndView中的数据可以从请求域中获取
processDispatchResult(processedRequest, response, mappedHandler,
mv, dispatchException);
} catch (Exception ex) {
triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
} catch (Error err) {
triggerAfterCompletionWithError(processedRequest, response, mappedHandler, err);
} finally {
if (asyncManager.isConcurrentHandlingStarted()) {
// Instead of postHandle and afterCompletion
mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
return;
}
// Clean up any resources used by a multipart request.
if (multipartRequestParsed) {
cleanupMultipart(processedRequest);
}
}
}</pre>
总体概览
-
用户发出请求，DispatcherServlet接收请求并拦截请求。
-
调用doDispatch()方法进行处理：
-
getHandler()：根据当前请求地址中找到能处理这个请求的目标处理器类(处理器)；
-
根据当前请求在HandlerMapping中找到这个请求的映射信息，获取到目标处理器类
-
mappedHandler = getHandler(processedRequest);
-
getHandlerAdapter()：根据当前处理器类找到能执行这个处理器方法的适配器；
-
根据当前处理器类，找到当前类的HandlerAdapter（适配器）
-
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
-
使用刚才获取到的适配器(AnnotationMethodHandlerAdapter)执行目标方法；
-
mv = ha.handle(processedRequest,response,mappedHandler.getHandler());
-
目标方法执行后，会返回一个ModerAndView对象
-
mv = ha.handle(processedRequest,response,mappedHandler.getHandler());
-
根据ModerAndView的信息转发到具体页面，并可以在请求域中取出ModerAndView中的模型数据
-
processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
HandlerMapping为处理器映射器，保存了每一个处理器能处理哪些请求的映射信息，handlerMap
HandlerAdapter为处理器适配器，能解析注解方法的适配器，其按照特定的规则去执行Handler
具体细节
步骤一：
getHandler():
**怎么根据当前请求就能找到哪个类能来处理？**
-
getHandler()会返回目标处理器类的执行链
-
HandlerMapping：处理器映射：他里面保存了每一个处理器能处理哪些请求的映射信息
-
handlerMap：ioc容器启动创建Controller对象的时候扫描每个处理器都能处理什么请求，保存在HandlerMapping的handlerMap属性中；下一次请求过来，就来看哪个HandlerMapping中有这个请求映射信息就行了
循环遍历拿到能处理url的类
protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
for (HandlerMapping hm : this.handlerMappings) {
if (logger.isTraceEnabled()) {
logger.trace(
"Testing handler map [" + hm + "] in DispatcherServlet with name '" + getServletName() + "'");
}
HandlerExecutionChain handler = hm.getHandler(request);
if (handler != null) {
return handler;
}
}
return null;
}
步骤二：
getHandlerAdapter():
如何找到目标处理器类的适配器。要拿适配器才去执行目标方法
AnnotationMethodHandlerAdapter：
-
能解析注解方法的适配器；
-
处理器类中只要有标了注解的这些方法就能用；
protected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException {
for (HandlerAdapter ha : this.handlerAdapters) {
if (logger.isTraceEnabled()) {
logger.trace("Testing handler adapter [" + ha + "]");
}
if (ha.supports(handler)) {
return ha;
}
}
throw new ServletException("No adapter for handler [" + handler +
"]: The DispatcherServlet configuration needs to include a HandlerAdapter that supports this handler");
}
步骤三：
执行目标方法的细节；
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
↓
return invokeHandlerMethod(request, response, handler);
protected ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
//拿到方法的解析器
ServletHandlerMethodResolver methodResolver = getMethodResolver(handler);
//方法解析器根据当前请求地址找到真正的目标方法
Method handlerMethod = methodResolver.resolveHandlerMethod(request);
//创建一个方法执行器；
ServletHandlerMethodInvoker methodInvoker = new ServletHandlerMethodInvoker(methodResolver);
//包装原生的request, response，
ServletWebRequest webRequest = new ServletWebRequest(request, response);
//创建了一个，隐含模型
ExtendedModelMap implicitModel = new BindingAwareModelMap();//**重点
//真正执行目标方法；目标方法利用反射执行期间确定参数值，提前执行modelattribute等所有的操作都在这个方法中；
Object result = methodInvoker.invokeHandlerMethod(handlerMethod, handler, webRequest, implicitModel);
//=======================看后边补充的代码块===========================
ModelAndView mav =
methodInvoker.getModelAndView(handlerMethod, handler.getClass(), result, implicitModel, webRequest);
methodInvoker.updateModelAttributes(handler, (mav != null ? mav.getModel() : null), implicitModel, webRequest);
return mav;
}</pre>
↓
Object result = methodInvoker.invokeHandlerMethod(handlerMethod, handler, webRequest, implicitModel);
publicfinal Object invokeHandlerMethod(Method handlerMethod, Object handler,
NativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception {
Method handlerMethodToInvoke = BridgeMethodResolver.findBridgedMethod(handlerMethod);
try {
boolean debug = logger.isDebugEnabled();
for (String attrName : this.methodResolver.getActualSessionAttributeNames()) {
Object attrValue = this.sessionAttributeStore.retrieveAttribute(webRequest, attrName);
if (attrValue != null) {
implicitModel.addAttribute(attrName, attrValue);
}
}
//找到所有@ModelAttribute注解标注的方法；
for (Method attributeMethod : this.methodResolver.getModelAttributeMethods()) {
Method attributeMethodToInvoke = BridgeMethodResolver.findBridgedMethod(attributeMethod);
//先确定modelattribute方法执行时要使用的每一个参数的值；
Object[] args = resolveHandlerArguments(attributeMethodToInvoke, handler, webRequest, implicitModel);
//==========================看后边补充的代码块=====================================
if (debug) {
logger.debug("Invoking model attribute method: " + attributeMethodToInvoke);
}
String attrName = AnnotationUtils.findAnnotation(attributeMethod, ModelAttribute.class).value();
if (!"".equals(attrName) && implicitModel.containsAttribute(attrName)) {
continue;
}
ReflectionUtils.makeAccessible(attributeMethodToInvoke);
//提前运行ModelAttribute，
Object attrValue = attributeMethodToInvoke.invoke(handler, args);
if ("".equals(attrName)) {
Class<?> resolvedType = GenericTypeResolver.resolveReturnType(attributeMethodToInvoke, handler.getClass());
attrName = Conventions.getVariableNameForReturnType(attributeMethodToInvoke, resolvedType, attrValue);
}
/*
方法上标注的ModelAttribute注解如果有value值
@ModelAttribute("abc")
hahaMyModelAttribute()
标了: attrName="abc"
没标: attrName="";attrName就会变为返回值类型首字母小写，
比如void ,或者book;
【
@ModelAttribute标在方法上的另外一个作用；
可以把方法运行后的返回值按照方法上@ModelAttribute("abc")
指定的key放到隐含模型中；
如果没有指定这个key；就用返回值类型的首字母小写
】
{
haha=Book [id=100, bookName=西游记, author=吴承恩, stock=98, sales=10, price=98.98],
void=null
}
*/
//把提前运行的ModelAttribute方法的返回值也放在隐含模型中
if (!implicitModel.containsAttribute(attrName)) {
implicitModel.addAttribute(attrName, attrValue);
}
}
//再次解析目标方法参数是哪些值
Object[] args = resolveHandlerArguments(handlerMethodToInvoke, handler, webRequest, implicitModel);
if (debug) {
logger.debug("Invoking request handler method: " + handlerMethodToInvoke);
}
ReflectionUtils.makeAccessible(handlerMethodToInvoke);
//执行目标方法
return handlerMethodToInvoke.invoke(handler, args);
}
catch (IllegalStateException ex) {
// Internal assertion failed (e.g. invalid signature):
// throw exception with full handler method context...
throw new HandlerMethodInvocationException(handlerMethodToInvoke, ex);
}
catch (InvocationTargetException ex) {
// User-defined @ModelAttribute/@InitBinder/@RequestMapping method threw an exception...
ReflectionUtils.rethrowException(ex.getTargetException());
return null;
}
}</pre>
确定方法运行时使用的每一个参数的值
Object[] args = resolveHandlerArguments(attributeMethodToInvoke, handler, webRequest, implicitModel);
@RequestMapping("/updateBook")
public String updateBook
(
@RequestParam(value="author")String author,
Map<String, Object> model,
HttpServletRequest request,
@ModelAttribute("haha")Book book
)
标了注解：
保存时哪个注解的详细信息；
如果参数有ModelAttribute注解；
拿到ModelAttribute注解的值让attrName保存
attrName="haha"
没标注解：
1）、先看是否普通参数（是否原生API）
再看是否Model或者Map，如果是就传入隐含模型；
2）、自定义类型的参数没有ModelAttribute 注解
1）、先看是否原生API
2）、再看是否Model或者Map
3）、再看是否是其他类型的比如SessionStatus、HttpEntity、Errors
4）、再看是否简单类型的属性；比如是否Integer，String，基本类型
如果是paramName=“”
5)、attrName=""；
如果是自定义类型对象，最终会产生两个效果；
1）、如果这个参数标注了ModelAttribute注解就给attrName赋值为这个注解的value值
2）、如果这个参数没有标注ModelAttribute注解就给attrName赋值""；
private Object[] resolveHandlerArguments(Method handlerMethod, Object handler,
NativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception {
Class<?>[] paramTypes = handlerMethod.getParameterTypes();
//创建了一个和参数个数一样多的数组，会用来保存每一个参数的值
Object[] args = new Object[paramTypes.length];
for (int i = 0; i < args.length; i++) {
MethodParameter methodParam = new MethodParameter(handlerMethod, i);
methodParam.initParameterNameDiscovery(this.parameterNameDiscoverer);
GenericTypeResolver.resolveParameterType(methodParam, handler.getClass());
String paramName = null;
String headerName = null;
boolean requestBodyFound = false;
String cookieName = null;
String pathVarName = null;
String attrName = null;
boolean required = false;
String defaultValue = null;
boolean validate = false;
Object[] validationHints = null;
int annotationsFound = 0;
Annotation[] paramAnns = methodParam.getParameterAnnotations();
//找到目标方法这个参数的所有注解，如果有注解就解析并保存注解的信息；
for (Annotation paramAnn : paramAnns) {
if (RequestParam.class.isInstance(paramAnn)) {
RequestParam requestParam = (RequestParam) paramAnn;
paramName = requestParam.value();
required = requestParam.required();
defaultValue = parseDefaultValueAttribute(requestParam.defaultValue());
annotationsFound++;
}
else if (RequestHeader.class.isInstance(paramAnn)) {
RequestHeader requestHeader = (RequestHeader) paramAnn;
headerName = requestHeader.value();
required = requestHeader.required();
defaultValue = parseDefaultValueAttribute(requestHeader.defaultValue());
annotationsFound++;
}
else if (RequestBody.class.isInstance(paramAnn)) {
requestBodyFound = true;
annotationsFound++;
}
else if (CookieValue.class.isInstance(paramAnn)) {
CookieValue cookieValue = (CookieValue) paramAnn;
cookieName = cookieValue.value();
required = cookieValue.required();
defaultValue = parseDefaultValueAttribute(cookieValue.defaultValue());
annotationsFound++;
}
else if (PathVariable.class.isInstance(paramAnn)) {
PathVariable pathVar = (PathVariable) paramAnn;
pathVarName = pathVar.value();
annotationsFound++;
}
else if (ModelAttribute.class.isInstance(paramAnn)) {
ModelAttribute attr = (ModelAttribute) paramAnn;
attrName = attr.value();
annotationsFound++;
}
else if (Value.class.isInstance(paramAnn)) {
defaultValue = ((Value) paramAnn).value();
}
else if (paramAnn.annotationType().getSimpleName().startsWith("Valid")) {
validate = true;
Object value = AnnotationUtils.getValue(paramAnn);
validationHints = (value instanceof Object[] ? (Object[]) value : new Object[] {value});
}
}
if (annotationsFound > 1) {
throw new IllegalStateException("Handler parameter annotations are exclusive choices - " +
"do not specify more than one such annotation on the same parameter: " + handlerMethod);
}
//没有找到注解的情况；
if (annotationsFound == 0) {
//解析普通参数
Object argValue = resolveCommonArgument(methodParam, webRequest);
//=====================看后边补充的代码块=========================
//会进入resolveStandardArgument（解析标准参数）
if (argValue != WebArgumentResolver.UNRESOLVED) {
args[i] = argValue;
}
else if (defaultValue != null) {
args[i] = resolveDefaultValue(defaultValue);
}
else {
//判断是否是Model或者是Map旗下的，如果是将之前创建的隐含模型直接赋值给这个参数
Class<?> paramType = methodParam.getParameterType();
if (Model.class.isAssignableFrom(paramType) || Map.class.isAssignableFrom(paramType)) {
if (!paramType.isAssignableFrom(implicitModel.getClass())) {
throw new IllegalStateException("Argument [" + paramType.getSimpleName() + "] is of type " +
"Model or Map but is not assignable from the actual model. You may need to switch " +
"newer MVC infrastructure classes to use this argument.");
}
args[i] = implicitModel;
}
else if (SessionStatus.class.isAssignableFrom(paramType)) {
args[i] = this.sessionStatus;
}
else if (HttpEntity.class.isAssignableFrom(paramType)) {
args[i] = resolveHttpEntityRequest(methodParam, webRequest);
}
else if (Errors.class.isAssignableFrom(paramType)) {
throw new IllegalStateException("Errors/BindingResult argument declared " +
"without preceding model attribute. Check your handler method signature!");
}
else if (BeanUtils.isSimpleProperty(paramType)) {
paramName = "";
}
else {
attrName = "";
}
}
}
//确定值的环节
if (paramName != null) {
args[i] = resolveRequestParam(paramName, required, defaultValue, methodParam, webRequest, handler);
}
else if (headerName != null) {
args[i] = resolveRequestHeader(headerName, required, defaultValue, methodParam, webRequest, handler);
}
else if (requestBodyFound) {
args[i] = resolveRequestBody(methodParam, webRequest, handler);
}
else if (cookieName != null) {
args[i] = resolveCookieValue(cookieName, required, defaultValue, methodParam, webRequest, handler);
}
else if (pathVarName != null) {
args[i] = resolvePathVariable(pathVarName, methodParam, webRequest, handler);
}
//确定自定义类型参数的值；还要将请求中的每一个参数赋值给这个对象
else if (attrName != null) {
WebDataBinder binder = resolveModelAttribute(attrName, methodParam, implicitModel, webRequest, handler);
//=====================看后边代码补充============================
boolean assignBindingResult = (args.length > i + 1 && Errors.class.isAssignableFrom(paramTypes[i + 1]));
if (binder.getTarget() != null) {
doBind(binder, webRequest, validate, validationHints, !assignBindingResult);
}
args[i] = binder.getTarget();
if (assignBindingResult) {
args[i + 1] = binder.getBindingResult();
i++;
}
implicitModel.putAll(binder.getBindingResult().getModel());
}
}
return args;
}</pre>
如果没有注解：
resolveCommonArgument）就是确定当前的参数是否是原生API；
@Override
protected Object resolveStandardArgument(Class<?> parameterType, NativeWebRequest webRequest) throws Exception {
HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class);
HttpServletResponse response = webRequest.getNativeResponse(HttpServletResponse.class);
if (ServletRequest.class.isAssignableFrom(parameterType) ||
MultipartRequest.class.isAssignableFrom(parameterType)) {
Object nativeRequest = webRequest.getNativeRequest(parameterType);
if (nativeRequest == null) {
throw new IllegalStateException(
"Current request is not of type [" + parameterType.getName() + "]: " + request);
}
return nativeRequest;
}
else if (ServletResponse.class.isAssignableFrom(parameterType)) {
this.responseArgumentUsed = true;
Object nativeResponse = webRequest.getNativeResponse(parameterType);
if (nativeResponse == null) {
throw new IllegalStateException(
"Current response is not of type [" + parameterType.getName() + "]: " + response);
}
return nativeResponse;
}
else if (HttpSession.class.isAssignableFrom(parameterType)) {
return request.getSession();
}
else if (Principal.class.isAssignableFrom(parameterType)) {
return request.getUserPrincipal();
}
else if (Locale.class.equals(parameterType)) {
return RequestContextUtils.getLocale(request);
}
else if (InputStream.class.isAssignableFrom(parameterType)) {
return request.getInputStream();
}
else if (Reader.class.isAssignableFrom(parameterType)) {
return request.getReader();
}
else if (OutputStream.class.isAssignableFrom(parameterType)) {
this.responseArgumentUsed = true;
return response.getOutputStream();
}
else if (Writer.class.isAssignableFrom(parameterType)) {
this.responseArgumentUsed = true;
return response.getWriter();
}
return super.resolveStandardArgument(parameterType, webRequest);
}</pre>
resolveModelAttribute
SpringMVC确定POJO值的三步；
1、如果隐含模型中有这个key（标了ModelAttribute注解就是注解指定的value，没标就是参数类型的首字母小写）指定的值；
如果有将这个值赋值给bindObject；
2、如果是SessionAttributes标注的属性，就从session中拿；
3、如果都不是就利用反射创建对象；
private WebDataBinder resolveModelAttribute(String attrName, MethodParameter methodParam,
ExtendedModelMap implicitModel, NativeWebRequest webRequest, Object handler) throws Exception {
// Bind request parameter onto object...
String name = attrName;
if ("".equals(name)) {
//如果attrName是空串；就将参数类型的首字母小写作为值
//Book book2121 -> name=book
name = Conventions.getVariableNameForParameter(methodParam);
}
Class<?> paramType = methodParam.getParameterType();
Object bindObject;
//确定目标对象的值
if (implicitModel.containsKey(name)) {
bindObject = implicitModel.get(name);
}
else if (this.methodResolver.isSessionAttribute(name, paramType)) {
bindObject = this.sessionAttributeStore.retrieveAttribute(webRequest, name);
if (bindObject == null) {
raiseSessionRequiredException("Session attribute '" + name + "' required - not found in session");
}
}
else {
bindObject = BeanUtils.instantiateClass(paramType);
}
WebDataBinder binder = createBinder(webRequest, bindObject, name);
initBinder(handler, name, binder, webRequest);
return binder;
}</pre>
总结：
-
运行流程简单版；
-
确定方法每个参数的值；
-
标注解：保存注解的信息；最终得到这个注解应该对应解析的值；
-
没标注解：
-
看是否是原生API；
-
看是否是Model或者是Map，SessionStatus、HttpEntity、Errors...
-
看是否是简单类型；paramName=""
-
给attrName赋值；attrName（参数标了@ModelAttribute("")就是指定的，没标就是""）
-
attrName使用参数的类型首字母小写；或者使用之前@ModelAttribute("")的值
-
先看隐含模型中有每个这个attrName作为key对应的值；如果有就从隐含模型中获取并赋值
-
看是否是@SessionAttributes(value="haha")；标注的属性，如果是从session中拿；
-
不是@SessionAttributes标注的，利用反射创建一个对象；
-
不是@SessionAttributes标注的，利用反射创建一个对象；
步骤四：
-
任何方法的返回值，最终都会被包装成ModelAndView对象
步骤五：
SpringMVC视图解析：
1、方法执行后的返回值会作为页面地址参考，转发或者重定向到页面
2、视图解析器可能会进行页面地址的拼串
processDispatchResult(processedRequest, response, mappedHandler,
mv, dispatchException);
-
调用processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException)
-
来到页面的方法视图渲染流程
-
将域中的数据在页面展示
-
页面就是用来渲染模型数据的
-
调用render(mv, request, response)
-
渲染页面
-
View与ViewResolver
-
ViewResolver的作用是根据视图名（方法的返回值）得到View对象
-
-
怎么能根据方法的返回值（视图名）得到View对象？
protected View resolveViewName(String viewName, Map<String, Object> model, Locale locale,
HttpServletRequest request) throws Exception {
//遍历所有的ViewResolver；
for (ViewResolver viewResolver : this.viewResolvers) {
//viewResolver视图解析器根据方法的返回值，得到一个View对象；
View view = viewResolver.resolveViewName(viewName, locale);
if (view != null) {
return view;
}
}
return null;
}</pre>
-
resolveViewName实现
@Override
public View resolveViewName(String viewName, Locale locale) throws Exception {
if (!isCache()) {
return createView(viewName, locale);
}
else {
Object cacheKey = getCacheKey(viewName, locale);
View view = this.viewAccessCache.get(cacheKey);
if (view == null) {
synchronized (this.viewCreationCache) {
view = this.viewCreationCache.get(cacheKey);
if (view == null) {
// Ask the subclass to create the View object.
//根据方法的返回值创建出视图View对象；
view = createView(viewName, locale);
if (view == null && this.cacheUnresolved) {
view = UNRESOLVED_VIEW;
}
if (view != null) {
this.viewAccessCache.put(cacheKey, view);
this.viewCreationCache.put(cacheKey, view);
if (logger.isTraceEnabled()) {
logger.trace("Cached view [" + cacheKey + "]");
}
}
}
}
}
return (view != UNRESOLVED_VIEW ? view : null);
}
}</pre> </li><li> <p>创建View对象</p> <p> </p> </li></ul><p> </p> <pre> @Override
protected View createView(String viewName, Locale locale) throws Exception {
// If this resolver is not supposed to handle the given view,
// return null to pass on to the next resolver in the chain.
if (!canHandle(viewName, locale)) {
return null;
}
// Check for special "redirect:" prefix.
if (viewName.startsWith(REDIRECT_URL_PREFIX)) {
String redirectUrl = viewName.substring(REDIRECT_URL_PREFIX.length());
RedirectView view = new RedirectView(redirectUrl, isRedirectContextRelative(), isRedirectHttp10Compatible());
return applyLifecycleMethods(viewName, view);
}
// Check for special "forward:" prefix.
if (viewName.startsWith(FORWARD_URL_PREFIX)) {
String forwardUrl = viewName.substring(FORWARD_URL_PREFIX.length());
return new InternalResourceView(forwardUrl);
}
// Else fall back to superclass implementation: calling loadView.
//如果没有前缀就使用父类默认创建一个View；
return super.createView(viewName, locale);
}</pre> <p> </p> <p> </p>
-
返回View对象
-
视图解析器得到View对象的流程就是，所有配置的视图解析器都来尝试根据视图名（返回值）得到View（视图）对象；如果能得到就返回，得不到就换下一个视图解析器；
-
调用View对象的render方法
@Override
public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
if (logger.isTraceEnabled()) {
logger.trace("Rendering view with name '" + this.beanName + "' with model " + model +
" and static attributes " + this.staticAttributes);
}
Map<String, Object> mergedModel = createMergedOutputModel(model, request, response);
prepareResponse(request, response);
//渲染要给页面输出的所有数据
renderMergedOutputModel(mergedModel, request, response);
}</pre> </li><li> <p>InternalResourceView有这个方法renderMergedOutputModel；</p> <pre>@Override
protected void renderMergedOutputModel(
Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
// Determine which request handle to expose to the RequestDispatcher.
HttpServletRequest requestToExpose = getRequestToExpose(request);
// Expose the model object as request attributes.
//将模型中的数据放在请求域中
exposeModelAsRequestAttributes(model, requestToExpose);
// Expose helpers as request attributes, if any.
exposeHelpers(requestToExpose);
// Determine the path for the request dispatcher.
String dispatcherPath = prepareForRendering(requestToExpose, response);
// Obtain a RequestDispatcher for the target resource (typically a JSP).
RequestDispatcher rd = getRequestDispatcher(requestToExpose, dispatcherPath);
if (rd == null) {
throw new ServletException("Could not get RequestDispatcher for [" + getUrl() +
"]: Check that the corresponding file exists within your web application archive!");
}
// If already included or response already committed, perform include, else forward.
if (useInclude(requestToExpose, response)) {
response.setContentType(getContentType());
if (logger.isDebugEnabled()) {
logger.debug("Including resource [" + getUrl() + "] in InternalResourceView '" + getBeanName() + "'");
}
rd.include(requestToExpose, response);
}
else {
// Note: The forwarded resource is supposed to determine the content type itself.
if (logger.isDebugEnabled()) {
logger.debug("Forwarding to resource [" + getUrl() + "] in InternalResourceView '" + getBeanName() + "'");
}
//转发页面
rd.forward(requestToExpose, response);
}
}</pre> </li><li> <p>将模型中的所有数据取出来全放在request域中</p> <pre>protected void exposeModelAsRequestAttributes(Map<String, Object> model, HttpServletRequest request) throws Exception {
for (Map.Entry<String, Object> entry : model.entrySet()) {
String modelName = entry.getKey();
Object modelValue = entry.getValue();
if (modelValue != null) {
//将ModelMap中的数据放到请求域中
request.setAttribute(modelName, modelValue);
if (logger.isDebugEnabled()) {
logger.debug("Added model object '" + modelName + "' of type [" + modelValue.getClass().getName() +
"] to request in view with name '" + getBeanName() + "'");
}
}
else {
request.removeAttribute(modelName);
if (logger.isDebugEnabled()) {
logger.debug("Removed model object '" + modelName +
"' from request in view with name '" + getBeanName() + "'");
}
}
}
}</pre> <p>总结：</p>
<ul><li> <p>视图解析器只是为了得到视图对象</p> </li><li> <p>视图对象才能真正的转发（将模型数据全部放在请求域中）或者重定向到页面视图对象才能真正的渲染视图</p> </li></ul></li><li> <p>ViewResolver</p> <p> </p> </li><li> <p>View:</p> <p> </p> </li></ul></li></ol>
8. 视图解析
8.1 forward和redirect前缀
通过SpringMVC来实现转发和重定向。
-
直接 return “success”，会走视图解析器进行拼串
-
转发：return “forward:/succes.jsp”；直接写绝对路径，/表示当前项目下，不走视图解析器
-
重定向：return “redirect:/success.jsp”；不走视图解析器
@Controller
public class ResultSpringMVC {
@RequestMapping("/hello01")
public String test1(){
//转发
//会走视图解析器
return "success";
}
@RequestMapping("/hello02")
public String test2(){
//转发二
//不走视图解析器
return "forward:/success.jsp";
}
@RequestMapping("/hello03")
public String test3(){
//重定向
//不走视图解析器
return "redirect:/success.jsp";
}
}
使用原生的ServletAPI时要注意，/路径需要加上项目名才能成功
@RequestMapping("/result/t2")
public void test2(HttpServletRequest req, HttpServletResponse resp) throwsIOException {
//重定向
resp.sendRedirect("/index.jsp");
}
@RequestMapping("/result/t3")
public void test3(HttpServletRequest req, HttpServletResponse resp) throwsException {
//转发
req.setAttribute("msg","/result/t3");
req.getRequestDispatcher("/WEB-INF/jsp/test.jsp").forward(req,resp);
}
8.2 jstlView
导包导入了jstl的时候会自动创建为一个jstlView；可以快速方便的支持国际化功能；
可以支持快速国际化；
javaWeb国际化步骤；
-
得得到一个Locale对象；
-
使用ResourceBundle绑定国际化资源文件
-
使用ResourceBundle.getString("key")；获取到国际化配置文件中的值
-
web页面的国际化，fmt标签库来做
-
<fmt:setLocale>
-
<fmt:setBundle>
-
<fmt:message>
有了JstlView以后
-
让Spring管理国际化资源就行
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/pages/"></property>
<property name="suffix" value=".jsp"></property>
<property name="viewClass" value="org.springframework.web.servlet.view.JstlView">
</property>
</bean>
<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
<property name="basename" value="i18n"></property>
</bean>
-
直接在页面使用<fmt:message>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>@%>
...
<h1>
<fmt:message key="welcomeinfo"/>
</h1>
<form action="">
<fmt:message key="username"/>:<input /><br/>
<fmt:message key="password"/>:<input /><br/>
<input type="submit" value='<fmt:message key="loginBtn"/>'/>
</form>
...
注意：
一定要过SpringMVC的视图解析流程，人家会创建一个jstlView帮你快速国际化；
-
不能写redirect:
-
不能写forward:
if (viewName.startsWith(FORWARD_URL_PREFIX)) {
String forwardUrl = viewName.substring(FORWARD_URL_PREFIX.length());
return new InternalResourceView(forwardUrl);
}
8.3 mvc:view-controller
mvc:view-controller：
直接将请求映射到某个页面，不需要写方法了：
注意：会走视图解析的功能
在ioc.xml中加入
<mvc:view-controller path="/toLogin" view-name="login"/>
<!--开启MVC注解驱动模式-->
<mvc:annotation-driven/>
8.4 自定义视图解析器
扩展：加深视图解析器和视图对象；
-
视图解析器根据方法的返回值得到视图对象
-
多个视图解析器都会尝试能否得到视图对象；
-
视图对象不同就可以具有不同功能
for (ViewResolver viewResolver : this.viewResolvers) {
//viewResolver视图解析器根据方法的返回值，得到一个View对象；
View view = viewResolver.resolveViewName(viewName, locale);
if (view != null) {
return view;
}
}
-
让我们的视图解析器工作
-
得到我们的视图对象
-
我们的视图对象自定义渲染逻辑
自定义视图和视图解析器的步骤
-
编写自定义的视图解析器，和视图实现类
public class MyViewResolver implements ViewResolver {
public View resolveViewName(String viewName, Locale locale) throws Exception {
if (viewName.startsWith("myView:")){
return new MyView();
}else{
return null;
}
}
} public class MyView implements View {
public String getContentType() {
return "text/html";
}
public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
System.out.println("保存的数据："+model);
response.getWriter().write("即将展现内容:");
}
}
-
视图解析器必须放在ioc容器中，让其工作，能创建出我们的自定义视图对象
<bean class="com.chenhui.view.MyViewResolver"></bean>
在源码中看到我们的编写的解析器
但是被InternalResourceViewResolver先拦截了执行了render
MyViewResolver要实现Ordered接口
public class MyViewResolver implements ViewResolver, Ordered {
private Integer order = 0;
public View resolveViewName(String viewName, Locale locale) throws Exception {
if (viewName.startsWith("myView:")) {
return new MyView();
} else {
return null;
}
}
public int getOrder() {
return this.order;
}
public void setOrder(Integer order) {
this.order = order;
}
}
<bean class="com.chenhui.view.MyViewResolver">
<property name="order" value="1"></property>
</bean>
发现顺序已经改变
到了我们的页面（虽然乱码），需要设置ContentType
response.setContentType("text/html ");
public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
System.out.println("保存的数据："+model);
response.setContentType("text/html ");
response.getWriter().write("即将展现内容:");
}
成功！
9. ResetCRUD
9.1 环境搭建
配置文件
ioc.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<context:component-scan base-package="com.chenhui"></context:component-scan>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/pages/"></property>
<property name="suffix" value=".jsp"></property>
</bean>
</beans>
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<servlet>
<servlet-name>dispatcherServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:ioc.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>dispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<filter>
<filter-name>CharacterEncodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
<init-param>
<param-name>forceEncoding</param-name>
<param-value>true</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>CharacterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
<filter-name>HiddenHttpMethodFilter</filter-name>
<filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>HiddenHttpMethodFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
bean
Employee
package com.chenhui.bean;
import java.util.Date;
public class Employee {
private Integer id;
private String lastName;
private String email;
//1 male, 0 female
private Integer gender;
private Department department;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public Integer getGender() {
return gender;
}
public void setGender(Integer gender) {
this.gender = gender;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
public Employee(Integer id, String lastName, String email, Integer gender,
Department department) {
super();
this.id = id;
this.lastName = lastName;
this.email = email;
this.gender = gender;
this.department = department;
}
public Employee() {
}
@Override
public String toString() {
return "Employee [id=" + id + ", lastName=" + lastName + ", email="
+ email + ", gender=" + gender + ", department=" + department
+ "]";
}
}
Department
package com.chenhui.bean;
import java.util.Date;
public class Employee {
private Integer id;
private String lastName;
private String email;
//1 male, 0 female
private Integer gender;
private Department department;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public Integer getGender() {
return gender;
}
public void setGender(Integer gender) {
this.gender = gender;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
public Employee(Integer id, String lastName, String email, Integer gender,
Department department) {
super();
this.id = id;
this.lastName = lastName;
this.email = email;
this.gender = gender;
this.department = department;
}
public Employee() {
}
@Override
public String toString() {
return "Employee [id=" + id + ", lastName=" + lastName + ", email="
+ email + ", gender=" + gender + ", department=" + department
+ "]";
}
}
dao
DepartmentDao
package com.chenhui.dao;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import com.chenhui.bean.Department;
import org.springframework.stereotype.Repository;
@Repository
public class DepartmentDao {
private static Map<Integer, Department> departments = null;
static{
departments = new HashMap<Integer, Department>();
departments.put(101, new Department(101, "D-AA"));
departments.put(102, new Department(102, "D-BB"));
departments.put(103, new Department(103, "D-CC"));
departments.put(104, new Department(104, "D-DD"));
departments.put(105, new Department(105, "D-EE"));
}
public Collection<Department> getDepartments(){
return departments.values();
}
public Department getDepartment(Integer id){
return departments.get(id);
}
}
EmployeeDao
package com.chenhui.dao;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import com.chenhui.bean.Department;
import com.chenhui.bean.Employee;
import org.springframework.stereotype.Repository;
import org.springframework.beans.factory.annotation.Autowired;
@Repository
public class EmployeeDao {
private static Map<Integer, Employee> employees = null;
@Autowired
private DepartmentDao departmentDao;
static{
employees = new HashMap<Integer, Employee>();
employees.put(1001, new Employee(1001, "E-AA", "aa@163.com", 1, new Department(101, "D-AA")));
employees.put(1002, new Employee(1002, "E-BB", "bb@163.com", 1, new Department(102, "D-BB")));
employees.put(1003, new Employee(1003, "E-CC", "cc@163.com", 0, new Department(103, "D-CC")));
employees.put(1004, new Employee(1004, "E-DD", "dd@163.com", 0, new Department(104, "D-DD")));
employees.put(1005, new Employee(1005, "E-EE", "ee@163.com", 1, new Department(105, "D-EE")));
}
private static Integer initId = 1006;
public void save(Employee employee){
if(employee.getId() == null){
employee.setId(initId++);
}
employee.setDepartment(departmentDao.getDepartment(employee.getDepartment().getId()));
employees.put(employee.getId(), employee);
}
public Collection<Employee> getAll(){
return employees.values();
}
public Employee get(Integer id){
return employees.get(id);
}
public void delete(Integer id){
employees.remove(id);
}
}
9.2 Controller编写
EmployeeController
package com.chenhui.controller;
import com.chenhui.bean.Department;
import com.chenhui.bean.Employee;
import com.chenhui.dao.DepartmentDao;
import com.chenhui.dao.EmployeeDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;
import java.util.Collection;
@Controller
public class EmployeeController {
@Autowired
EmployeeDao employees;
@Autowired
DepartmentDao departments;
@RequestMapping(value = "/emp", method = RequestMethod.GET)
public String getEmps(Model model) {
Collection<Employee> all = employees.getAll();
model.addAttribute("emps", all);
return "list";
}
@RequestMapping(value = "/emp", method = RequestMethod.POST)
public String addEmp(Employee employee, Model model) {
employees.save(employee);
return "redirect:/emp";
}
@RequestMapping(value = "/emp/{id}", method = RequestMethod.GET)
public String getEmp(@PathVariable("id") Integer id, Model model) {
Employee employee = employees.get(id);
Collection<Department> departments = this.departments.getDepartments();
//此处给spring表单添加一个employee对象，以免发生command未找到的异常
model.addAttribute("employee", employee);
model.addAttribute("departments", departments);
return "editEmp";
}
@RequestMapping(value = "/emp/{id}", method = RequestMethod.PUT)
public String updateEmp(@ModelAttribute("employee") Employee employee, @PathVariable("id") Integer integer) {
System.out.println("要修改的：" + employee);
employees.save(employee);
return "redirect:/emp";
}
@RequestMapping(value = "/emp/{id}", method = RequestMethod.DELETE)
public String deleteEmp(@PathVariable("id") Integer id) {
employees.delete(id);
return "redirect:/emp";
}
@ModelAttribute
public void myMethodAttribute(@RequestParam(value = "id", required = false) Integer id, Model model) {
System.out.println("modelAttribute");
if (id != null) {
Employee employee = employees.get(id);
model.addAttribute("employee", employee);
}
}
@RequestMapping("/toaddpage")
public String toAddPage(Model model) {
Collection<Department> all = departments.getDepartments();
model.addAttribute("departments", all);
model.addAttribute("command", new Employee());
return "addEmp";
}
}
9.3 Jsp编写
list.jsp
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
Created by IntelliJ IDEA.
User: admin
Date: 2020/11/13
Time: 9:18
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>员工列表</title>
</head>
<body>
<% pageContext.setAttribute("ctp", request.getContextPath());
// System.out.println(request.getContextPath());
%>
<h1>员工列表</h1>
<table border="1" cellpadding="5px" cellspacing="0">
<%--
private Integer id;
private String lastName;
private String email;
//1 male, 0 female
private Integer gender;
private Department department;--%>
<thead>
<tr>
<th>ID</th>
<th>lastName</th>
<th>email</th>
<th>gender</th>
<th>departmentName</th>
<th>EDIT</th>
<th>DELETE</th>
</tr>
</thead>
<tbody>
<c:forEach items="${emps}" var="emp">
<tr>
<td>${emp.id}</td>
<td>${emp.lastName}</td>
<td>${emp.email}</td>
<td>${emp.gender==0?"女":"男"}</td>
<td>${emp.department.departmentName}</td>
<td><a href="${ctp}/emp/${emp.id}">修改</a></td>
<!--删除操作可以绑定单击事件，使用ajax发送delete请求-->
<td>
<form action="${ctp}/emp/${emp.id}" method="post">
<input type="hidden" name="_method" value="DELETE">
<input type="submit" value="delete">
</form>
</td>
</tr>
</c:forEach>
</tbody>
</table>
<a href="toaddpage">添加员工</a>
</body>
</html>
addEmp.jsp
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%--
Created by IntelliJ IDEA.
User: admin
Date: 2020/11/13
Time: 9:42
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>添加员工</title>
</head>
<body>
原生表单：<br>
<%
pageContext.setAttribute("ctp",request.getContextPath());
%>
<form action="${ctp}/emp" method="post">
姓名：<input type="text" name="lastName"><br>
邮箱：<input type="text" name="email"><br>
性别：<br>
男：<input type="radio" name="gender" value="1"><br>
女：<input type="radio" name="gender" value="0"><br>
部门：<select name="department.id">
<c:forEach items="${departments}" var="department">
<option value="${department.id}">${department.departmentName}</option>
</c:forEach>
</select>
<input type="submit" value="提交">
</form>
SpringMVC表单：<br>
<form:form action="${ctp}/emp" method="post">
姓名：<form:input path="lastName"></form:input><br>
邮箱：<form:input path="email"></form:input><br>
性别：<br>
男：<form:radiobutton path="gender" value="1"></form:radiobutton>
女：<form:radiobutton path="gender" value="0"></form:radiobutton><br>
部门：<form:select path="department.id" items="${departments}"
itemLabel="departmentName" itemValue="id">
</form:select>
<input type="submit" value="提交">
</form:form>
</body>
</html>
Spring表单需要在model中添加command：
<form:form action="" modelAttribute="xxxx">
也可以用modelAttribute替换command变量名
-
command对象的信息会放在SpringForm中
@RequestMapping("/toaddpage")
public String toAddPage(Model model) {
Collection<Department> all = departments.getDepartments();
model.addAttribute("departments", all);
model.addAttribute("command", new Employee());
return "addEmp";
}</pre>
不然Spring表单会报错：
editEmp.jsp
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%--
Created by IntelliJ IDEA.
User: admin
Date: 2020/11/13
Time: 11:34
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
pageContext.setAttribute("ctp", request.getContextPath());
%>
<html>
<head>
<title>编辑员工</title>
</head>
<body>
<form:form action="${ctp}/emp/${employee.id}" method="post" modelAttribute="employee">
<input type="hidden" name="_method" value="put">
<input type="hidden" name="id" value="${employee.id}">
姓名：<form:input path="lastName"></form:input><br>
邮箱：<form:input path="email"></form:input><br>
性别：<br>
男：<form:radiobutton path="gender" value="1"></form:radiobutton>
女：<form:radiobutton path="gender" value="0"></form:radiobutton><br>
部门：
<form:select path="department.id" items="${departments}"
itemLabel="departmentName" itemValue="id">
</form:select>
<input type="submit" value="修改">
</form:form>
</body>
</html>
9.4 解决DispatcherServlet拦截静态文件
让Tomcat托管js文件
-
在ioc.xml文件中加入
<mvc:default-servlet-handler/>
<mvc:annotation-driven/>
10. 数据转换 & 数据格式化 & 数据校验
10.1 数据转换
SpringMVC封装自定义类型对象的时候？
javaBean要和页面提交的数据进行一一绑定？
1）、页面提交的所有数据都是字符串？
2）、Integer age,Date birth;
employName=zhangsan&age=18&gender=1
String age = request.getParameter("age");
牵扯到以下操作；
1）、数据绑定期间的数据类型转换？String--Integer String--Boolean,xxx
2）、数据绑定期间的数据格式化问题？比如提交的日期进行转换
birth=2017-12-15----->Date 2017/12/15 2017.12.15 2017-12-15
3）、数据校验？
我们提交的数据必须是合法的？
前端校验：js+正则表达式；
后端校验：重要数据也是必须的；
1）、校验成功！数据合法
2）、校验失败？
bindRequestParameters方法将请求参数于JavaBean进行绑定，为自定义对象赋值。
ModelAttributeMethodProcessor
public final Object resolveArgument(
MethodParameter parameter, ModelAndViewContainer mavContainer,
NativeWebRequest request, WebDataBinderFactory binderFactory)
throws Exception {
String name = ModelFactory.getNameForParameter(parameter);
Object attribute = (mavContainer.containsAttribute(name)) ?
mavContainer.getModel().get(name) : createAttribute(name, parameter, binderFactory, request);
//WebDataBinder
WebDataBinder binder = binderFactory.createBinder(request, attribute, name);
if (binder.getTarget() != null) {
//将页面提交过来的数据封装到javaBean的属性中
bindRequestParameters(binder, request);
//+++++++++
validateIfApplicable(binder, parameter);
if (binder.getBindingResult().hasErrors()) {
if (isBindExceptionRequired(binder, parameter)) {
throw new BindException(binder.getBindingResult());
}
}
}
WebDataBinder：
数据绑定器有什么用？
-
数据绑定器负责数据绑定工作
-
数据绑定期间产生的类型转换、格式化、数据校验等问题
-
conversionService组件：
-
负责数据类型的转换以及格式化功能；
-
ConversionService中有非常多的converter；
-
不同类型的转换和格式化用它自己的converter
...
@org.springframework.format.annotation.DateTimeFormat java.util.Date -> java.lang.String: org.springframework.format.datetime.DateTimeFormatAnnotationFormatterFactory@32abc654
@org.springframework.format.annotation.NumberFormat java.lang.Double -> java.lang.String: org.springframework.format.number.NumberFormatAnnotationFormatterFactory@140bb45d
@org.springframework.format.annotation.NumberFormat java.lang.Float -> java.lang.String: org.springframework.format.number.NumberFormatAnnotationFormatterFactory@140bb45d
....
org.springframework.format.number.NumberFormatAnnotationFormatterFactory@140bb45d
java.lang.String -> @org.springframework.format.annotation.NumberFormat java.math.BigInteger: org.springframework.format.number.NumberFormatAnnotationFormatterFactory@140bb45d
java.lang.String -> java.lang.Boolean : org.springframework.core.convert.support.StringToBooleanConverter@22f562e2
java.lang.String -> java.lang.Character : org.springframework.core.convert.support.StringToCharacterConverter@5f2594f5
java.lang.String -> java.lang.Enum : org.springframework.core.convert.support.StringToEnumConverterFactory@1347a7be
【java.lang.String -> java.lang.Number :
...
java...
-
validators负责数据校验工作
-
bindingResult负责保存以及解析数据绑定期间数据校验产生的错误
自定义类型转换器：
步骤：
-
ConversionService:：是一个接口
-
Converter是ConversionService中的组件；
-
Converter得放进ConversionService 中；
-
将WebDataBinder中的ConversionService设置成我们这个加了自定义类型转换器的ConversionService；
-
配置ConversionService
需要实现的步骤
-
实现Converter接口，写一个自定义的类型转换器
public class MyStringToEmployeeConverter implements Converter<String, Employee> {
@Autowired
DepartmentDao departmentDao;
public Employee convert(String source) {
System.out.println("将要转换的字符串" + source);
Employee employee = new Employee();
if (source.contains("-")) {
String[] split = source.split("-");
employee.setLastName(split[0]);
employee.setEmail(split[1]);
employee.setGender(Integer.parseInt(split[2]));
employee.setDepartment(departmentDao.getDepartment(Integer.parseInt(split[3])));
}
return employee;
}
}
-
配置出ConversionService
在ioc.xml中
<bean id="myconversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
<!--
ConversionServiceFactoryBean:
创建的ConversionService组件是没有格式化器(formatter)存在的；
推荐使用：
"org.springframework.format.support.FormattingConversionServiceFactoryBean"
-->
<property name="converters">
<set>
<bean class="com.chenhui.component.MyStringToEmployeeConverter"/>
</set>
</property>
</bean>
-
让SpringMVC用我们的ConversionService
<mvc:annotation-driven conversion-service="myconversionService"></mvc:annotation-driven>
动态资源和静态资源访问
-
<mvc:default-servlet-handler/> 与 <mvc:annotation-driven/>
-
都没配
-
动态能访问：
DefaultAnnotationHandlerMapping中的handlerMap中保存了每一个资源的映射信息
-
静态不能访问：
handlerMap中没有保存静态资源映射的请求
-
handleAdapter
-
<mvc:default-servlet-handler/>不加<mvc:annotation-driven/>
-
动态不能访问：DefaultAnnotationHandlerMapping被SimpleUrlHandlerMapping替换。
-
静态能访问的原因：SimpleUrlHandlerMapping把所有请求都映射给tomcat；
-
handleAdapter
-
都加上
-
都能访问
handlerMap
-
RequestMappingHandlerMapping:动态资源可以访问
handleMethods属性保存了每一个请求用哪个方法来处理；
SimpleUrlHandlerMapping：将请求直接交给tomcat；有他，静态资源就没问题
-
handleAdapter
原来的AnnotationMethodHandlerAdapter被换成RequestMappingHandlerAdapter
-
只加<mvc:annotation-driven/>
-
动态能访问，静态无法访问
10.2 数据格式化
自定义数据格式化
-
在属性上加Format标签
-
更改转换器
例：
@DateTimeFormat(pattern = "yyyy-MM-dd")
private Date birth;
<bean id="myconversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
<property name="converters">
<set>
<bean class="com.chenhui.component.MyStringToEmployeeConverter"/>
</set>
</property>
</bean>
10.3 数据校验
步骤
-
导入Jar包
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>1.1.0.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>5.4.1.Final</version>
</dependency>
<dependency>
<groupId>org.jboss.logging</groupId>
<artifactId>jboss-logging</artifactId>
<version>3.3.0.Final</version>
</dependency>
<dependency>
<groupId>com.fasterxml</groupId>
<artifactId>classmate</artifactId>
<version>1.3.3</version>
</dependency></pre>
-
在变量上放上注解，错误信息message
@NotNull
@Length(min = 5, max = 10,message='xxxx')
private String lastName;
@DateTimeFormat(pattern = "yyyy-MM-dd")
@Past
private Date birth;
-
对SpringMVC封装对象加上@Valid注解
-
校验结果在BindingResult的result中
@RequestMapping(value = "/emp", method = RequestMethod.POST)
public String addEmp(@Valid Employee employee, BindingResult result, Model model) {
if (result.hasErrors()){
System.out.println("有校验错误");
return "addEmp";
}else{
employees.save(employee);
}
return "redirect:/emp";
}</pre>
-
来到页面使用form:errors取出错误信息
-
可以把错误信息存到Model中，然后在页面中取Model的对应的key
<form:form action="${ctp}/emp" method="post">
姓名：<form:input path="lastName"></form:input><form:errors path="lastName"></form:errors><br>
邮箱：<form:input path="email"></form:input><form:errors path="email"></form:errors><br>
生日：<form:input path="birth"></form:input><form:errors path="birth"></form:errors><br>
性别：<br>
男：<form:radiobutton path="gender" value="1"></form:radiobutton>
女：<form:radiobutton path="gender" value="0"></form:radiobutton><br>
部门：<form:select path="department.id" items="${departments}"
itemLabel="departmentName" itemValue="id">
</form:select>
<input type="submit" value="提交">
</form:form>
原生Form显示错误：
1）、原生的表单怎么办？ 将错误放在Model中就行了
国际化定制
国际化定制自己的错误消息显示
编写国际化的文件
-
errors_zh_CN.properties
-
errors_en_US.properties
key有规定（精确优先）：
codes
[
Email.employee.email, 校验规则.隐含模型中这个对象的key.对象的属性
Email.email, 校验规则.属性名
Email.java.lang.String, 校验规则.属性类型
Email
];
1、先编写国际化配置文件
2、让SpringMVC管理国际化资源文件
<!-- 管理国际化资源文件 -->
<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
<property name="basename" value="errors"></property>
</bean>
3、来到页面取值
4、高级国际化？
动态传入消息参数；
{0}：永远都是当前属性名；
@Length(min = 5, max = 10,message='xxxx')
按照字母排序
{1}为max {2}为min
11. 其他数据响应与接受
ajax；
1、SpringMVC快速的完成ajax功能？
1）、返回数据是json就ok；
2）、页面,$.ajax()；
2、原生javaWeb：
1）、导入GSON；
2）、返回的数据用GSON转成json
3）、写出去；
3、SpringMVC-ajax：
1、导包
jackson-annotations-2.1.5.jar
jackson-core-2.1.5.jar
jackson-databind-2.1.5.jar
2、写配置
3、测试
11.1 Json数据响应与接受
ResponseBody
maven导入包
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.1.5</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.1.5</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.1.5</version>
</dependency>
@Controller
public class AjaxController {
@Autowired
EmployeeDao employeeDao;
@ResponseBody
@RequestMapping("/getallajax")
public Collection<Employee> ajaxGetAll() {
Collection<Employee> all = employeeDao.getAll();
return all;
}
}
-
@JsonIgnore可以忽略字段
-
@JsonFormat(pattern="")
-
@DateTimeFormat(pattern = "yyyy-MM-dd")
@Past
@JsonFormat(pattern = "yyyy-MM-dd")
private Date birth;
private String email;
//1 male, 0 female
private Integer gender;
@JsonIgnore
private Department department;</pre> <p>输入：</p> <p> </p> <p>结果：</p> <p> </p> </li></ul>
RequestBody
-
可以接受json数据
HttpEntity<String>
-
代替RequestBody，
-
不仅能拿请求体数据，还能拿请求头数据
ResponseEntity<String>
-
可以设置响应头
11.2 文件上传与下载
文件上传
单文件上传:
maven导入包
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.0</version>
</dependency>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.2.1</version>
</dependency>
编写控制器
package com.chenhui.controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;
import java.io.File;
import java.io.IOException;
@Controller
public class FileUploadController {
@RequestMapping("/upload")
public String upload(@RequestParam(value = "username", required = false) String username,
@RequestParam(value = "headerImg", required = false) MultipartFile file,
Model model){
System.out.println("上传信息");
System.out.println("文件名"+file.getName());
System.out.println("文件初始名"+file.getOriginalFilename());
try {
file.transferTo(new File("D:\\upload\\"+file.getOriginalFilename()));
model.addAttribute("message","文件上传成功");
} catch (IOException e) {
e.printStackTrace();
model.addAttribute("message","文件上传失败"+e.getCause());
}
return "list";
}
}
注册文件上传解析器
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="#{1024*1024*20}"></property>
<property name="defaultEncoding" value="utf-8"></property>
</bean>
编写jsp页面
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
Created by IntelliJ IDEA.
User: admin
Date: 2020/11/13
Time: 9:18
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>员工列表</title>
</head>
<body>
<% pageContext.setAttribute("ctp", request.getContextPath());
// System.out.println(request.getContextPath());
%>
<a href="toaddpage">添加员工</a><br>
<hr>
<h1>${message}</h1>
<form action="${ctp}/upload" method="post" enctype="multipart/form-data">
头像：<input type="file" name="headerImg">
昵称：<input type="text" name="username">
<input type="submit" value="提交">
</form>
</body>
</html>
结果
多文件上传:
@Controller
public class FileUploadController {
@RequestMapping("/upload")
public String upload(@RequestParam(value = "username", required = false) String username,
@RequestParam(value = "headerImg", required = false) MultipartFile[] files,
Model model){
for(MultipartFile file: files){
System.out.println("上传信息");
System.out.println("文件名"+file.getName());
System.out.println("文件初始名"+file.getOriginalFilename());
if(!file.isEmpty()){
try {
file.transferTo(new File("D:\\upload\\"+file.getOriginalFilename()));
model.addAttribute("message","文件上传成功");
} catch (IOException e) {
e.printStackTrace();
model.addAttribute("message","文件上传失败"+e.getCause());
}
}
return "list";
}
}
}
文件下载
@Controller
public class DownloadController {
@RequestMapping(value = "/DownLoad/{fileName}/{fileType}", method = RequestMethod.GET)
public ResponseEntity<byte[]> download(HttpServletRequest request, @PathVariable String fileName, @PathVariable String fileType) throws IOException {
File file = new File("D:\\Apks\\" + fileName + "." + fileType);
byte[] body = null;
InputStream is = new FileInputStream(file);
body = new byte[is.available()];
is.read(body);
HttpHeaders headers = new HttpHeaders();
headers.add("Content-Disposition", "attchement;filename=" + file.getName());
HttpStatus statusCode = HttpStatus.OK;
ResponseEntity<byte[]> entity = new ResponseEntity<>(body, headers, statusCode);
return entity;
}
}
11.3 HttpMessageConverter<T>接口:
Spring3.0 新添加的一个接口，负责
将请求信息转换为一个对象（类型为 T）
将对象（类型为 T）输出为响应信息
注意：一般Controller返回String类型是走视图解析（ViewResolver）
如果返回其他类型是由HttpMessageConverter负责
HttpMessageConverter<T>接口定义的方法：
-
Boolean canRead(Class<?> clazz,MediaType mediaType):
-
指定转换器可以读取的对象类型，即转换器是否可将请求信息转换为 clazz 类型的对象，同时指定支持 MIME 类型(text/html,applaiction/json等)
-
Boolean canWrite(Class<?> clazz,MediaType mediaType):
-
指定转换器是否可将 clazz 类型的对象写到响应流中，响应流支持的媒体类型在MediaType 中定义
-
LIst<MediaType> getSupportMediaTypes()：
-
该转换器支持的媒体类型
-
T read(Class<? extends T> clazz,HttpInputMessage inputMessage)：
-
将请求信息流转换为 T 类型的对象
-
void write(T t,MediaType contnetType,HttpOutputMessgae outputMessage):
-
将T类型的对象写到响应流中，同时指定相应的媒体类型为 contentType
12. 拦截器
SpringMVC提供了拦截器机制： 允许运行目标方法之前进行一些拦截工作，或者目标方法运行之后进行一些其他处理。 Filter：javaWeb HandlerInterceptor：SpringMVC
HandlerInterceptor：
-
preHandle：在目标方法运行之前调用：
-
返回boolean
-
return true；(chain.doFilter())放行；
-
return false；不放行
-
postHandle：在目标方法运行之后调用
-
afterCompletion：资源响应之后调用
12.1 操作步骤
-
实现HandlerInterceptor接口
package com.chenhui.interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MyFirstInterceptor implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("MyFirstInterceptor...preHandle");
return true;
}
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("MyFirstInterceptor...postHandle");
}
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("MyFirstInterceptor...afterCompletion");
}
}
-
配置拦截器
<mvc:interceptors>
<!--默认拦截所有请求↓-->
<!-- <bean class="com.chenhui.interceptor.MyFirstInterceptor"></bean>-->
<!--拦截具体请求↓-->
<mvc:interceptor>
<!--只拦截path所对应的请求-->
<mvc:mapping path="/testInter"/>
<bean class="com.chenhui.interceptor.MyFirstInterceptor"></bean>
</mvc:interceptor>
</mvc:interceptors></pre> <p>testInter控制器如下</p> <pre>@Controller
public class InterceptorTestController {
@RequestMapping("/testInter")
public String testInterceptor(){
return "hello";
}
}
hello.jsp：
<% pageContext.setAttribute("ctp",request.getContextPath());%>
<%@ page contentType="text/html;charset=UTF-8" language="java" pageEncoding="UTF-8" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<a href="testInter">测试拦截器</a>
</body>
</html>
<%--<jsp:forward page="/emp"></jsp:forward>--%>
-
拦截器的运行流程
-
preHandle
-
目标方法
-
postHandle
-
页面渲染
-
afterCompletion
其他流程：
-
只要preHandle不放行就没有以后的流程；
-
preHandle return false
-
只要放行了，afterCompletion都会执行；
-
目标方法出现异常，afterCompletion也会执行
12.2 多个拦截器
MyFirstInterceptor...preHandle...
MySecondInterceptor...preHandle...
目标方法....
MySecondInterceptor...postHandle...
MyFirstInterceptor...postHandle...
响应页面....
MySecondInterceptor...afterCompletion...
MyFirstInterceptor...afterCompletion
异常流程：
-
哪一块Interceptor不放行
-
哪一块不放行从此以后都没有
-
MySecondInterceptor不放行
-
但是他前面已经放行了的拦截器的afterCompletion总会执行
总结interceptor的流程：
拦截器的preHandle：是按照顺序执行
拦截器的postHandle：是按照逆序执行
拦截器的afterCompletion：是按照逆序执行
已经放行了的拦截器的afterCompletion总会执行
12.3 拦截器源码
在DispatcherServlet中
try {
ModelAndView mv = null;
Exception dispatchException = null;
try {
processedRequest = checkMultipart(request);
multipartRequestParsed = processedRequest != request;
// Determine handler for the current request.拿到方法的执行链，包含拦截器
mappedHandler = getHandler(processedRequest);
if (mappedHandler == null || mappedHandler.getHandler() == null) {
noHandlerFound(processedRequest, response);
return;
}
// Determine handler adapter for the current request.
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
// Process last-modified header, if supported by the handler.
String method = request.getMethod();
boolean isGet = "GET".equals(method);
if (isGet || "HEAD".equals(method)) {
long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
if (logger.isDebugEnabled()) {
String requestUri = urlPathHelper.getRequestUri(request);
logger.debug("Last-Modified value for [" + requestUri + "] is: " + lastModified);
}
if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
return;
}
}
//拦截器preHandle执行位置;有一个拦截器返回false目标方法以后都不会执行；直接跳到afterCompletion
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}
try {
// Actually invoke the handler.适配器执行目标方法
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
}
finally {
if (asyncManager.isConcurrentHandlingStarted()) {
return;
}
}
applyDefaultViewName(request, mv);
//目标方法只要正常就会走到postHandle;任何期间有异常
mappedHandler.applyPostHandle(processedRequest, response, mv);
}
catch (Exception ex) {
dispatchException = ex;
}
//页面渲染；如果完蛋也是直接跳到afterCompletion；
processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
}
catch (Exception ex) {
triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
}
catch (Error err) {
triggerAfterCompletionWithError(processedRequest, response, mappedHandler, err);
}
finally {
if (asyncManager.isConcurrentHandlingStarted()) {
// Instead of postHandle and afterCompletion
mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
return;
}
// Clean up any resources used by a multipart request.
if (multipartRequestParsed) {
cleanupMultipart(processedRequest);
}
}
}</pre>
顺序遍历所有拦截器的preHandle方法
boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {
if (getInterceptors() != null) {
for (int i = 0; i < getInterceptors().length; i++) {
HandlerInterceptor interceptor = getInterceptors()[i];
//preHandle-true-false
if (!interceptor.preHandle(request, response, this.handler)) {
//执行完afterCompletion（）;
triggerAfterCompletion(request, response, null);
//返回一个false
return false;
}
//记录一下索引
//this.interceptorIndex = i;
}
}
return true;
}</pre>
逆序遍历所有拦截器的postHandle方法
void applyPostHandle(HttpServletRequest request, HttpServletResponse response, ModelAndView mv) throws Exception {
if (getInterceptors() == null) {
return;
}
//逆向执行每个拦截器的postHandle
for (int i = getInterceptors().length - 1; i >= 0; i--) {
HandlerInterceptor interceptor = getInterceptors()[i];
interceptor.postHandle(request, response, this.handler, mv);
}
}
页面渲染方法
private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
HandlerExecutionChain mappedHandler, ModelAndView mv, Exception exception) throws Exception {
boolean errorView = false;
if (exception != null) {
if (exception instanceof ModelAndViewDefiningException) {
logger.debug("ModelAndViewDefiningException encountered", exception);
mv = ((ModelAndViewDefiningException) exception).getModelAndView();
}
else {
Object handler = (mappedHandler != null ? mappedHandler.getHandler() : null);
mv = processHandlerException(request, response, handler, exception);
errorView = (mv != null);
}
}
// Did the handler return a view to render?
if (mv != null && !mv.wasCleared()) {
//页面渲染
render(mv, request, response);
if (errorView) {
WebUtils.clearErrorRequestAttributes(request);
}
}
else {
if (logger.isDebugEnabled()) {
logger.debug("Null ModelAndView returned to DispatcherServlet with name '" + getServletName() +
"': assuming HandlerAdapter completed request handling");
}
}
if (WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {
// Concurrent handling started during a forward
return;
}
if (mappedHandler != null) {
//页面正常执行afterCompletion；即使没走到这，afterCompletion总会执行；
mappedHandler.triggerAfterCompletion(request, response, null);
}
}</pre>
afterCompletion：
void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, Exception ex)
throws Exception {
if (getInterceptors() == null) {
return;
}
//有记录最后一个放行拦截器的索引，从他开始把之前所有放行的拦截器的afterCompletion都执行
for (int i = this.interceptorIndex; i >= 0; i--) {
HandlerInterceptor interceptor = getInterceptors()[i];
try {
interceptor.afterCompletion(request, response, this.handler, ex);
}
catch (Throwable ex2) {
logger.error("HandlerInterceptor.afterCompletion threw exception", ex2);
}
}
}</pre>
第二个拦截器不放行的情况：
preHandle：
第一次：ConversionServiceExposingInterceptor interceptorIndex=0；
第二次：MyFirstInterceptor interceptorIndex=1
第三次；MySecondInterceptor 执行afterCompletion()
已经放行了的拦截器的afterCompletion总会执行
从记录的索引开始倒叙执行afterCompletion方法：
for (int i = this.interceptorIndex; i >= 0; i--) {
HandlerInterceptor interceptor = getInterceptors()[i];
try {
interceptor.afterCompletion(request, response, this.handler, ex);
}
catch (Throwable ex2) {
logger.error("HandlerInterceptor.afterCompletion threw exception", ex2);
}
}
13. 国际化
13.1 步骤
-
写好国际化资源文件
username=UserName
password=PassWord
login=Login
username=用户名
password=密码
login=登录
-
让Spring的ResourceBundleMessageSource管理国际化资源文件
<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
<property name="basename" value="loginpage/login"></property>
</bean> -
直接去页面取值
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form>
<fmt:message key="username"/>：<input type="text"><br>
<fmt:message key="password"/>：<input type="password"><br>
<input type="submit" value="<fmt:message key="login"/>">
</form>
</body>
</html>
-
现象：是按照浏览器带来语言信息决定
13.2 自定义LocaleResolver
实现LocaleResolver接口
public class MyLocalResolver implements LocaleResolver {
public Locale resolveLocale(HttpServletRequest request) {
System.out.println("自己的区域解析器");
Locale l = null;
String locale = request.getParameter("locale");
System.out.println("自己区域解析器接受的locale:"+locale);
if (locale != null && !"".equals(locale)) {
l = new Locale(locale.split("_")[0], locale.split("_")[1]);
} else {
l = request.getLocale();
}
System.out.println("Locale:"+l.toString());
return l;
}
public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {
throw new UnsupportedOperationException("Can't set Locale message");
}
}
注册到ioc.xml中
<bean id="localeResolver" class="com.chenhui.component.MyLocalResolver"></bean>
jsp页面修改为
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form>
<fmt:message key="username"/>：<input type="text"><br>
<fmt:message key="password"/>：<input type="password"><br>
<input type="submit" value="<fmt:message key="login"/>">
</form>
<a href="tologinpage?locale=zh_CN">中文</a>
<a href="tologinpage?locale=en_US">英文</a>
</body>
</html>
效果
13.3 FixedLocaleResolver：
使用系统默认的区域信息
@Override
public Locale resolveLocale(HttpServletRequest request) {
Locale locale = getDefaultLocale();
if (locale == null) {
locale = Locale.getDefault();
}
return locale;
}
@Override
public LocaleContext resolveLocaleContext(HttpServletRequest request) {
return new TimeZoneAwareLocaleContext() {
@Override
public Locale getLocale() {
return getDefaultLocale();
}
@Override
public TimeZone getTimeZone() {
return getDefaultTimeZone();
}
};
}
@Override
public void setLocaleContext(HttpServletRequest request, HttpServletResponse response, LocaleContext localeContext) {
throw new UnsupportedOperationException("Cannot change fixed locale - use a different locale resolution strategy");
}</pre>
13.4 SessionLocaleResolver：
区域信息是从session中获取，可以根据请求参数创建一个locale对象，把他放在session中。
@Override
public Locale resolveLocale(HttpServletRequest request) {
Locale locale = (Locale) WebUtils.getSessionAttribute(request, LOCALE_SESSION_ATTRIBUTE_NAME);
if (locale == null) {
locale = determineDefaultLocale(request);
}
return locale;
}
13.5 CookieLocaleResolver
区域信息是从cookie中获取
@Override
public Locale resolveLocale(HttpServletRequest request) {
parseLocaleCookieIfNecessary(request);
return (Locale) request.getAttribute(LOCALE_REQUEST_ATTRIBUTE_NAME);
}
14. 异常处理
14.1 异常源码
processDispatchResult(processedRequest, response, mappedHandler,
mv, dispatchException);
加了MVC异常处理，默认就是这个几个HandlerExceptionResolver
-
ExceptionHandlerExceptionResolver
-
ResponseStatusExceptionResolver
-
DefaultHandlerExceptionResolver
如果异常解析器都不能处理就直接抛出去；
private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
HandlerExecutionChain mappedHandler, ModelAndView mv, Exception exception) throws Exception {
boolean errorView = false;
//如果有异常
if (exception != null) {
if (exception instanceof ModelAndViewDefiningException) {
logger.debug("ModelAndViewDefiningException encountered", exception);
mv = ((ModelAndViewDefiningException) exception).getModelAndView();
}
else {
//处理异常
Object handler = (mappedHandler != null ? mappedHandler.getHandler() : null);
//===================================
mv = processHandlerException(request, response, handler, exception);
errorView = (mv != null);
}
}
// Did the handler return a view to render?
if (mv != null && !mv.wasCleared()) {
//来到页面
render(mv, request, response);
if (errorView) {
WebUtils.clearErrorRequestAttributes(request);
}
}
else {
if (logger.isDebugEnabled()) {
logger.debug("Null ModelAndView returned to DispatcherServlet with name '" + getServletName() +
"': assuming HandlerAdapter completed request handling");
}
}
if (WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {
// Concurrent handling started during a forward
return;
}
if (mappedHandler != null) {
mappedHandler.triggerAfterCompletion(request, response, null);
}
}</pre>
所有异常解析器尝试解析，解析完成进行后续，解析失败下一个解析器继续解析
protected ModelAndView processHandlerException(HttpServletRequest request, HttpServletResponse response,
Object handler, Exception ex) throws Exception {
// Check registered HandlerExceptionResolvers...
ModelAndView exMv = null;
for (HandlerExceptionResolver handlerExceptionResolver : this.handlerExceptionResolvers) {
exMv = handlerExceptionResolver.resolveException(request, response, handler, ex);
if (exMv != null) {
break;
}
}
if (exMv != null) {
if (exMv.isEmpty()) {
return null;
}
// We might still need view name translation for a plain error model...
if (!exMv.hasView()) {
exMv.setViewName(getDefaultViewName(request));
}
if (logger.isDebugEnabled()) {
logger.debug("Handler execution resulted in exception - forwarding to resolved error view: " + exMv, ex);
}
WebUtils.exposeErrorRequestAttributes(request, ex, getServletName());
return exMv;
}
throw ex;
}
14.2 ExceptionHandler
局部异常处理
@Controller
public class ExceptionTestController {
@RequestMapping("/testException")
public String exceptionTest(Integer integer){
System.out.println("testException");
System.out.println(10/integer);
return "exception";
}
@ExceptionHandler(value = {ArithmeticException.class})
public String handleException01(){
System.out.println("handleException-Arithmetic");
return "myError";
}
}
Jsp页面：
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>运算出错</h1>
</body>
</html>
若要携带异常信息, 可以返回ModelAndView
注意：
-
异常信息不能给参数位置写Model
-
同个作用域，有多个Exception异常处理器，精确优先
@ExceptionHandler(value = {ArithmeticException.class})
public ModelAndView handleException01(Exception exception){
System.out.println("handleException-Arithmetic");
System.out.println("exception:"+exception);
ModelAndView myError = new ModelAndView("myError");
myError.addObject("ex",exception);
return myError;
}
全局异常处理
异常处理控制器可以放在@ControllerAdvice下，作用域是全局
@ControllerAdvice
public class MyExceptionController {
@ExceptionHandler(value = {ArithmeticException.class})
public ModelAndView handleException01(Exception exception){
System.out.println("handleException-Arithmetic");
System.out.println("exception:"+exception);
ModelAndView myError = new ModelAndView("myError");
myError.addObject("ex",exception);
return myError;
}
}
全局与本类都有匹配的异常处理器，本类的优先运行
14.3 ResponseStatus
编写一个异常类
package com.chenhui.component;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;
@ResponseStatus(reason = "拒绝登录", value = HttpStatus.NOT_ACCEPTABLE)
public class UsernameNotFoundException extends RuntimeException {
static final long serialVersionUID = 1L;
}
测试：
@RequestMapping("/testException2")
public String exceptionTest2(String username){
System.out.println("testException");
if (!"admin".equals(username)){
System.out.println("登录失败");
//+++++抛出自己的错误信息
throw new UsernameNotFoundException();
}
System.out.println("登陆成功");
return "success";
}</pre>
结果：
14.4 DefaultHandlerExceptionResolver
DefaultHandlerExceptionResolver:
判断是否是SpringMVC自带的异常或Spring自己的异常：
如：HttpRequestMethodNotSupportedException。如果没人处理则它自己处理
默认的异常有
try {
if (ex instanceof NoSuchRequestHandlingMethodException) {
return handleNoSuchRequestHandlingMethod((NoSuchRequestHandlingMethodException) ex, request, response,
handler);
}
else if (ex instanceof HttpRequestMethodNotSupportedException) {
return handleHttpRequestMethodNotSupported((HttpRequestMethodNotSupportedException) ex, request,
response, handler);
}
else if (ex instanceof HttpMediaTypeNotSupportedException) {
return handleHttpMediaTypeNotSupported((HttpMediaTypeNotSupportedException) ex, request, response,
handler);
}
else if (ex instanceof HttpMediaTypeNotAcceptableException) {
return handleHttpMediaTypeNotAcceptable((HttpMediaTypeNotAcceptableException) ex, request, response,
handler);
}
else if (ex instanceof MissingServletRequestParameterException) {
return handleMissingServletRequestParameter((MissingServletRequestParameterException) ex, request,
response, handler);
}
else if (ex instanceof ServletRequestBindingException) {
return handleServletRequestBindingException((ServletRequestBindingException) ex, request, response,
handler);
}
else if (ex instanceof ConversionNotSupportedException) {
return handleConversionNotSupported((ConversionNotSupportedException) ex, request, response, handler);
}
else if (ex instanceof TypeMismatchException) {
return handleTypeMismatch((TypeMismatchException) ex, request, response, handler);
}
else if (ex instanceof HttpMessageNotReadableException) {
return handleHttpMessageNotReadable((HttpMessageNotReadableException) ex, request, response, handler);
}
else if (ex instanceof HttpMessageNotWritableException) {
return handleHttpMessageNotWritable((HttpMessageNotWritableException) ex, request, response, handler);
}
else if (ex instanceof MethodArgumentNotValidException) {
return handleMethodArgumentNotValidException((MethodArgumentNotValidException) ex, request, response, handler);
}
else if (ex instanceof MissingServletRequestPartException) {
return handleMissingServletRequestPartException((MissingServletRequestPartException) ex, request, response, handler);
}
else if (ex instanceof BindException) {
return handleBindException((BindException) ex, request, response, handler);
}
else if (ex instanceof NoHandlerFoundException) {
return handleNoHandlerFoundException((NoHandlerFoundException) ex, request, response, handler);
}
}
catch (Exception handlerException) {
logger.warn("Handling of [" + ex.getClass().getName() + "] resulted in Exception", handlerException);
}
return null;
}
14.5 SimpleMappingExceptionResolver：
通过配置的方式进行异常处理
<bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
<!-- exceptionMappings：配置哪些异常去哪些页面 -->
<property name="exceptionMappings">
<props>
<!-- key：异常全类名；value：要去的页面视图名；会走视图解析 -->
<prop key="java.lang.NullPointerException">myerror</prop>
</props>
</property>
<!--指定错误信息取出时使用的key -->
<property name="exceptionAttribute" value="ex"></property>
</bean>
15. SpringMVC总结
SpringMVC运行流程：
1、所有请求，前端控制器（DispatcherServlet）收到请求，调用doDispatch进行处理
2、根据HandlerMapping中保存的请求映射信息找到，处理当前请求的，处理器执行链（包含拦截器）
3、根据当前处理器找到他的HandlerAdapter（适配器）
4、拦截器的preHandle先执行
5、适配器执行目标方法，并返回ModelAndView
1）、ModelAttribute注解标注的方法提前运行
2）、执行目标方法的时候（确定目标方法用的参数）
1）、有注解
2）、没注解：
1）、 看是否Model、Map以及其他的
2）、如果是自定义类型
1）、从隐含模型中看有没有，如果有就从隐含模型中拿
2）、如果没有，再看是否SessionAttributes标注的属性，如果是从Session中拿，如果拿不到会抛异常
3）、都不是，就利用反射创建对象
6、拦截器的postHandle执行
7、处理结果；（页面渲染流程）
1）、如果有异常使用异常解析器处理异常；处理完后还会返回ModelAndView
2）、调用render进行页面渲染
1）、视图解析器根据视图名得到视图对象
2）、视图对象调用render方法；
3）、执行拦截器的afterCompletion；
16. SpringMVC与Spring整合
16.1 分容目的
-
SpringMVC和Spring整合的目的：分工明确
-
SpringMVC的配置文件就来配置和网站转发逻辑以及网站功能有关的
（视图解析器，文件上传解析器，支持ajax，xxx）
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Spring的配置文件来配置和业务有关的（事务控制，数据源，xxx）
16.2 SpringMVC和Spring分容器
Spring管理业务逻辑组件
<context:component-scan base-package="com.atguigu">
<context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
<context:exclude-filter type="annotation" expression="org.springframework.web.bind.annotation.ControllerAdvice"/>
</context:component-scan>
SpringMVC管理控制器组件
<context:component-scan base-package="com.atguigu" use-default-filters="false">
<context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
<context:include-filter type="annotation" expression="org.springframework.web.bind.annotation.ControllerAdvice"/>
</context:component-scan>
Spring是一个父容器
SpringMVC是一个子容器
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子容器还可以引用父容器的组件
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父容器不能引用子容器的组件
