我爱Java系列---【 SpringMVC 入门案例】

一、整体流程（三大件：DispatcherServlet,HandlerMapping,HandlerAdapter）

二、具体步骤（对上图步骤做了精简化处理，便于理解）

第一步：浏览器付出请求

第二步：请求到达服务器（springmvc 对地址进行处理）前端控制器（拿到地址）

第三步：前端控制器找处理器映射器对地址进行处理变成数据链返回给前端控制器

第四步：去找适配器适配根据数据链找到对应的处理器（就是我们自己写的那个controller类）

第五步：处理器进行业务处理然后得到结果吧这个结果（把结果放到一个模型（modelandview）对象）给适配器适配器中转给前端控制器

第六步：找视图解析器把模型（modelandview）进行整理整理后的结果有给前端控制器

第七步：把6步得到的结果进行页面的渲染得到一张页面同时响应回浏览器

三、开发步骤

1.导入依赖

2、配置前端控制器（配置在web.xml 参考servlet的配置方式）
3、在springMVC的核心配置文件里面配<mvc: 作用：相当于拥有了映射器和适配器
4、配视图解析器
5、使用的时候传入参数（模型（modelandview）对象）

四、代码演示

准备工作：导入依赖

 1 <dependency>
 2       <groupId>javax.servlet</groupId>
 3       <artifactId>javax.servlet-api</artifactId>
 4       <version>3.1.0</version>
 5       <scope>provided</scope>
 6     </dependency>
 7     <dependency>
 8       <groupId>javax.servlet.jsp</groupId>
 9       <artifactId>javax.servlet.jsp-api</artifactId>
10       <version>2.3.3</version>
11       <scope>provided</scope>
12     </dependency>
13     <dependency>
14       <groupId>javax.servlet</groupId>
15       <artifactId>jstl</artifactId>
16       <version>1.2</version>
17     </dependency>
18     <!-- JSTL stop -->
19     <dependency>
20       <groupId>taglibs</groupId>
21       <artifactId>standard</artifactId>
22       <version>1.1.2</version>
23     </dependency>
24 
25     <dependency>
26       <groupId>org.springframework</groupId>
27       <artifactId>spring-context</artifactId>
28       <version>5.1.8.RELEASE</version>
29     </dependency>
30     <dependency>
31       <groupId>org.springframework</groupId>
32       <artifactId>spring-webmvc</artifactId>
33       <version>5.1.8.RELEASE</version>
34     </dependency>
35     <dependency>

1、创建 web.xml 文件

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
 3          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4          xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
 5          version="3.1">
 6     
 7     <servlet>
 8         <servlet-name>springmvc</servlet-name>
 9         <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
10         <!--配置初始化参数，用于读取 SpringMVC 的配置文件
11             在springmvc配置文件中指定要扫描的controller所在的包的路径-->
12         <init-param>
13             <param-name>contextConfigLocation</param-name>
14             <param-value>classpath:springmvc.xml</param-value>
15         </init-param>
16 
17         <!-- 配置 servlet 的对象的创建时间点：应用加载时创建。
18             取值只能是非 0 正整数，表示启动顺序 -->
19         <load-on-startup>1</load-on-startup>
20     </servlet>
21     <servlet-mapping>
22         <servlet-name>springmvc</servlet-name>
23        <!-- <url-pattern>*.do</url-pattern>-->
24         <url-pattern>/</url-pattern><!--接收所有请求-->
25     </servlet-mapping>
26     
27     <filter>
28         <filter-name>encodingFilter</filter-name>
29         <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
30         <init-param>
31             <param-name>encoding</param-name>
32             <param-value>utf-8</param-value>
33         </init-param>
34     </filter>
35     <filter-mapping>
36         <filter-name>encodingFilter</filter-name>
37         <url-pattern>/*</url-pattern>
38     </filter-mapping>
39     
40 </web-app>

2.创建springmvc.xml文件

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4        xmlns:context="http://www.springframework.org/schema/context"
 5        xmlns:mvc="http://www.springframework.org/schema/cache"
 6      
 7        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache.xsd">
 8     <!--指定要扫描的UserController所在的包的路径，这样就可以扫描类中的注解了，此时类中的注解才能正常被spring容器所操作-->
 9     <context:component-scan base-package="com.heima.web"></context:component-scan>
10 
11     <!--指明我就是要用requestMapping handler映射处理器
12         //两个原因：
13                 版本原因  其实RequestMappingHandlerMapping在以前版本就已经有这个类了，但是5.0以前版本，默认并不是这个
14                 其他的原因  转换 Jason转换  自定义格式转换 都需要他
15                 -->
16     <!--<mvc:annotation-driven></mvc:annotation-driven>-->相当于有了映射器和适配器
17 
18     <!--定制化内部视图解析器-->
19     <bean id="InternalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
20 
21         <property name="prefix" value="/WEB-INF/pages/"/>
22         <property name="suffix" value=".jsp"/>
23     </bean>
24 </beans>

3.创建UserController类

  1 @Controller//1.把UserController这个类放进spring容器中
  2 @RequestMapping("/user")
  3 public class UserController {
  4     @RequestMapping("/test1")//2.指定下面这个方法所映射的路径
  5     public ModelAndView test1(ModelAndView modelAndView){
  6         Date date = new Date();
  7         String content = "当前时间："+date.toLocaleString();
  8         //类似于request.setAttribute("属性名"，"属性值")
  9         modelAndView.addObject("content",content);
 10         //等同于request.getDispatcher("").forward(request,response)
 11         modelAndView.setViewName("user/list");
 12         return modelAndView;
 13 
 14     }
 15 
 16     @RequestMapping("/test2_1")
 17     public ModelAndView test2(ModelAndView modelAndView,int id){
 18         System.out.println(id);
 19         Date date = new Date();
 20         String content = "当前时间："+date.toLocaleString();
 21         //类似于request.setAttribute("属性名"，"属性值")
 22         modelAndView.addObject("content",content);
 23         //等同于request.getDispatcher("").forward(request,response)
 24         modelAndView.setViewName("hello/Hello");
 25         return modelAndView;
 26 
 27     }
 28     @RequestMapping("/test2_2")
 29     public ModelAndView test2_2(ModelAndView modelAndView,User user){
 30         System.out.println(user);
 31         Date date = new Date();
 32         String content = "当前时间："+date.toLocaleString();
 33         //类似于request.setAttribute("属性名"，"属性值")
 34         modelAndView.addObject("content",content);
 35         //等同于request.getDispatcher("").forward(request,response)
 36         modelAndView.setViewName("hello/Hello");
 37         return modelAndView;
 38 
 39     }
 40 
 41     @RequestMapping(value = "/test3",method = RequestMethod.POST)
 42     public ModelAndView test3(ModelAndView modelAndView,User user){
 43         System.out.println(user);
 44         Date date = new Date();
 45         String content = "当前时间："+date.toLocaleString();
 46         //类似于request.setAttribute("属性名"，"属性值")
 47         modelAndView.addObject("content",content);
 48         //等同于request.getDispatcher("").forward(request,response)
 49         modelAndView.setViewName("user/list");
 50         return modelAndView;
 51 
 52     }
 53     /*params表示必须传的参数*/
 54     @RequestMapping(value = "/test4",params = "username")
 55     public ModelAndView test4(ModelAndView modelAndView,User user){
 56         System.out.println(user);
 57         Date date = new Date();
 58         String content = "当前时间："+date.toLocaleString();
 59         //类似于request.setAttribute("属性名"，"属性值")
 60         modelAndView.addObject("content",content);
 61         //等同于request.getDispatcher("").forward(request,response)
 62         modelAndView.setViewName("user/list");
 63         return modelAndView;
 64 
 65     }
 66 
 67     /*headers表示必须带"user-agent"请求头，这个默认带，换一个就报404了*/
 68     @RequestMapping(value = "/test5",headers = "user-agent")//
 69     public ModelAndView test5(ModelAndView modelAndView,User user){
 70         System.out.println(user);
 71         Date date = new Date();
 72         String content = "当前时间："+date.toLocaleString();
 73         //类似于request.setAttribute("属性名"，"属性值")
 74         modelAndView.addObject("content",content);
 75         //等同于request.getDispatcher("").forward(request,response)
 76         modelAndView.setViewName("user/list");
 77         return modelAndView;
 78 
 79     }
 80 
 81 /*@RequestParam 解决三个问题：1.大部分情况为了解决不传参问题，给定默认值
 82                              2.为了解决前后端参数名不同步问题，前后端参数名不一致
 83                              3.最后才是为了解决编译导致无参数名问题
 84  */
 85 
 86     @RequestMapping(value = "/test6")//@RequestParam(name = "id")可以防止setting-->java compiler-->generate debugging info没有被选中
 87                                     //若没有被选中，程序只认识数据类型，却识别不出来数据名，@RequestParam(name = "id")可以强制指明数据名
 88     public ModelAndView test6(ModelAndView modelAndView, @RequestParam(name = "id",defaultValue = "123") int id, @RequestParam(name = "username")String username,@RequestParam(name = "price")double price){
 89         System.out.println(id+"---"+username+"---"+price);
 90 
 91         Date date = new Date();
 92         String content = "当前时间："+date.toLocaleString();
 93         //类似于request.setAttribute("属性名"，"属性值")
 94         modelAndView.addObject("content",content);
 95         //等同于request.getDispatcher("").forward(request,response)
 96         modelAndView.setViewName("user/list");
 97         return modelAndView;
 98 
 99     }
100 
101     /*javaBean数据的绑定，注意参数名一定要与类里的属性名保持一致*/
102     @RequestMapping(value = "/test7")
103     public ModelAndView test7(ModelAndView modelAndView,User user){
104         System.out.println(user);
105 
106         Date date = new Date();
107         String content = "当前时间："+date.toLocaleString();
108         //类似于request.setAttribute("属性名"，"属性值")
109         modelAndView.addObject("content",content);
110         //等同于request.getDispatcher("").forward(request,response)
111         modelAndView.setViewName("user/list");
112         return modelAndView;
113 
114     }
115 
116     /*javaBean数据的绑定，注意参数名一定要与类里的属性名保持一致*/
117     @RequestMapping(value = "/test8")
118     public ModelAndView test8(ModelAndView modelAndView,User user){
119         System.out.println(user);
120 
121         Date date = new Date();
122         String content = "当前时间："+date.toLocaleString();
123         //类似于request.setAttribute("属性名"，"属性值")
124         modelAndView.addObject("content",content);
125         //等同于request.getDispatcher("").forward(request,response)
126         modelAndView.setViewName("user/list");
127         return modelAndView;
128 
129     }
130 
131 
132     /*复合对象类型数组是参数数据的绑定，注意：前端name=user.username*/
133     @RequestMapping(value = "/test9")
134     public ModelAndView test9(ModelAndView modelAndView, QueryVo queryVo){
135         System.out.println(queryVo);
136 
137         Date date = new Date();
138         String content = "当前时间："+date.toLocaleString();
139         //类似于request.setAttribute("属性名"，"属性值")
140         modelAndView.addObject("content",content);
141         //等同于request.getDispatcher("").forward(request,response)
142         modelAndView.setViewName("user/list");
143         return modelAndView;
144 
145     }
146 
147     /*复合对象类型map集合是对象数据的绑定，注意:前端name=smap['name'],定义map不能用map关键字*/
148     @RequestMapping(value = "/test10")
149     public ModelAndView test10(ModelAndView modelAndView, QueryVo queryVo){
150         System.out.println(queryVo);
151 
152         Date date = new Date();
153         String content = "当前时间："+date.toLocaleString();
154         //类似于request.setAttribute("属性名"，"属性值")
155         modelAndView.addObject("content",content);
156         //等同于request.getDispatcher("").forward(request,response)
157         modelAndView.setViewName("user/list");
158         return modelAndView;
159         }
160 
161     //练习11 演示复合对象类型list集合是对象参数绑定
162     @RequestMapping(value = "/test11")
163     public ModelAndView test11(ModelAndView modelAndView, QueryVo queryVo){
164         System.out.println(queryVo);
165 
166         Date date = new Date();
167         String content = "当前时间："+date.toLocaleString();
168         //类似于request.setAttribute("属性名"，"属性值")
169         modelAndView.addObject("content",content);
170         //等同于request.getDispatcher("").forward(request,response)
171         modelAndView.setViewName("user/list");
172         return modelAndView;
173     }
174 }

4.创建User类，和QueryVo类

 1 public class User {
 2     private int id;
 3     private String username;
 4     private String desc;
 5 
 6     @Override
 7     public String toString() {
 8         return "User{" +
 9                 "id=" + id +
10                 ", username='" + username + '\'' +
11                 ", desc='" + desc + '\'' +
12                 '}';
13     }
14 
15     public int getId() {
16         return id;
17     }
18 
19     public void setId(int id) {
20         this.id = id;
21     }
22 
23     public String getUsername() {
24         return username;
25     }
26 
27     public void setUsername(String username) {
28         this.username = username;
29     }
30 
31     public String getDesc() {
32         return desc;
33     }
34 
35     public void setDesc(String desc) {
36         this.desc = desc;
37     }
38 }

 1 public class QueryVo {
 2     private User user;
 3     private int age;
 4     private String [] hobbies;
 5     private Map smap;
 6     private List<User> users;
 7 
 8     public List<User> getUsers() {
 9         return users;
10     }
11 
12     public void setUsers(List<User> users) {
13         this.users = users;
14     }
15 
16     public Map getSmap() {
17         return smap;
18     }
19 
20     public void setSmap(Map smap) {
21         this.smap = smap;
22     }
23 
24     public String[] getHobbies() {
25         return hobbies;
26     }
27 
28     public void setHobbies(String[] hobbies) {
29         this.hobbies = hobbies;
30     }
31 
32     public User getUser() {
33         return user;
34     }
35 
36     public void setUser(User user) {
37         this.user = user;
38     }
39 
40     public int getAge() {
41         return age;
42     }
43 
44     public void setAge(int age) {
45         this.age = age;
46     }
47 
48 
49     @Override
50     public String toString() {
51         return "QueryVo{" +
52                 "user=" + user +
53                 ", age=" + age +
54                 ", hobbies=" + Arrays.toString(hobbies) +
55                 ", smap=" + smap +
56                 ", users=" + users +
57                 '}';
58     }
59 }

5.创建前端页面list.jsp和index.jsp

list.jsp页面 
1 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
 2 <html>
 3 <head>
 4     <title>Title</title>
 5 </head>
 6 <body>
 7 <div style="text-align: center ;margin:100px 100px;color: blue;">
 8     <font size="20px">${content}</font>
 9 </div>
10 </body>
11 </html>

index.jsp页面 
 1 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  2 <html>
  3 <head>
  4     <meta charset="UTF-8">
  5 </head>
  6 <body>
  7 <h2>Hello World!</h2>
  8 <div>
  9     <fieldset>
 10         <legend>练习1</legend>
 11         <a href="/user/test1">常规使用1</a>
 12     </fieldset>
 13 
 14     <fieldset>
 15         <legend>练习2</legend>
 16         <a href="/user/test2_1">常规使用2</a>
 17     </fieldset>
 18 
 19     <fieldset>
 20         <legend>练习3</legend>
 21         <a href="/user/test3">指明请求必须是某类型</a>
 22         <form action="/user/test3" method="post">
 23             <input type="text" name="username"><br>
 24             <input type="submit" value="点我提交">
 25         </form>
 26 
 27     </fieldset>
 28 
 29     <fieldset>
 30         <legend>练习4</legend>
 31         <a href="/user/test4">演示RequestMapping必须传某某参数</a>
 32         <form action="/user/test4" >
 33             <input type="text" name="username"><br>
 34             <input type="submit" value="点我提交">
 35         </form>
 36 
 37     </fieldset>
 38 
 39     <fieldset>
 40         <legend>练习5</legend>
 41         <a href="/user/test5">演示带某某请求</a>
 42         <form action="/user/test5" >
 43             <input type="text" name="username"><br>
 44             <input type="submit" value="点我提交">
 45         </form>
 46 
 47     </fieldset>
 48 
 49     <fieldset>
 50         <legend>练习6</legend>
 51         <a href="/user/test6">演示简单类型的参数绑定</a>
 52         <form action="/user/test6" >
 53             id:<input type="text" name="id"><br>
 54             username:<input type="text" name="username"><br>
 55             price:<input type="text" name="price"><br>
 56             <input type="submit" value="点我提交">
 57         </form>
 58 
 59     </fieldset>
 60 
 61     <fieldset>
 62         <legend>练习7</legend>
 63         <a href="/user/test7">演示javaBean的参数绑定</a>
 64         <form action="/user/test7" >
 65             id:<input type="text" name="id"><br>
 66             用户名:<input type="text" name="username"><br>
 67             描述:<input type="text" name="desc"><br>
 68             <input type="submit" value="点我提交">
 69         </form>
 70 
 71     </fieldset>
 72 
 73     <fieldset>
 74         <legend>练习8</legend>
 75         <a href="/user/test8">演示复合对象的参数绑定</a>
 76         <form action="/user/test8" >
 77             id:<input type="text" name="user.id"><br>
 78             age:<input type="text" name="age"><br>
 79             用户名:<input type="text" name="user.username"><br>
 80             描述:<input type="text" name="user.desc"><br>
 81             <input type="submit" value="点我提交">
 82         </form>
 83 
 84     </fieldset>
 85 
 86     <fieldset>
 87         <legend>练习9</legend>
 88         <a href="/user/test9">演示复合对象的数组参数的绑定</a>
 89         <form action="/user/test9" >
 90             id:<input type="text" name="user.id"><br>
 91             age:<input type="text" name="age"><br>
 92             用户名:<input type="text" name="user.username"><br>
 93             描述:<input type="text" name="user.desc"><br>
 94             爱好：<input type="checkbox" name="hobbies" value="抽烟">抽烟
 95                   <input type="checkbox" name="hobbies" value="喝酒">喝酒
 96                   <input type="checkbox" name="hobbies" value="烫头">烫头 <br>
 97                   <input type="submit" value="点我提交">
 98         </form>
 99     </fieldset>
100 
101     <fieldset>
102         <legend>练习10</legend>
103         <a href="/user/test10">演示复合对象的map集合参数的绑定</a>
104         <form action="/user/test10" >
105             id:<input type="text" name="user.id"><br>
106             age:<input type="text" name="age"><br>
107             用户名:<input type="text" name="user.username"><br>
108             描述:<input type="text" name="user.desc"><br>
109             爱好：<input type="checkbox" name="hobbies" value="抽烟">抽烟
110             <input type="checkbox" name="hobbies" value="喝酒">喝酒
111             <input type="checkbox" name="hobbies" value="烫头">烫头 <br>
112             收款人：<input type="text" name="smap['name']">
113             电话：<input type="text" name="smap['tel']">
114             <input type="submit" value="点我提交">
115         </form>
116     </fieldset>
117 
118     <fieldset>
119         <legend>练习11</legend>
120         <a href="/user/test11">演示复合对象类型list集合是对象的参数绑定</a>
121         <form action="/user/test11" >
122             用户名:<input type="text" name="user.username"><br>
123             爱好：<input type="checkbox" name="hobbies" value="抽烟">抽烟
124             <input type="checkbox" name="hobbies" value="喝酒">喝酒
125             <input type="checkbox" name="hobbies" value="烫头">烫头 <br>
126             收款人：<input type="text" name="smap['name']">
127             电话：<input type="text" name="smap['tel']">
128 
129             收货人列表:<br>
130             收货人1:<input type="text" name="users[0].id"><input type="text" name="users[0].username"><br>
131             收货人2:<input type="text" name="users[1].id"><input type="text" name="users[1].username"><br>
132             收货人3:<input type="text" name="users[2].id"><input type="text" name="users[2].username"><br>
133             <input type="submit" value="点我提交">
134         </form>
135     </fieldset>
136 </div>
137 </body>
138 </html>