SpringMVC入门及拦截器
SSM最后一个框架springmvc，其实上手特别简单。但是我昨天看一个深入源码的视频，差点GG。其实以前学过很多东西，都忘了，不敢说学会，现在有了本书，看过一遍之后。多多少少记住一些，权当我会用了，不敢说精通。
本周计划，今天把springmvc搞完，明天搭建一个SSM项目，by the way 其实我毕设就是SSM项目。周三复习Maven，周四复习Redis，周五开始做SSM+Redis整合。下周开搞SSH，最后学习SpringBoot。这个月的主要事情就是学习框架。
springmvc的实际容器类是XmlWebApplicationContext。在web.xml文件中，如果我们使用idea的新建springmvc项目功能，会自动进行简单配置，非常聪明，我们一般需要进行字符过滤器CharacterEncoderingFilter的设置，启动参数context-param，来启动spring容器，spring容器是一个大的容器，包含springmvc容器。
web.xml配置如下
<?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_3_1.xsd" version="3.1"> <context-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/applicationContext.xml</param-value> </context-param> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <servlet> <servlet-name>dispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:dispatcher-servlet.xml</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>dispatcher</servlet-name> <url-pattern>*.form</url-pattern> </servlet-mapping> <filter> <filter-name>encoder</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> </filter> <filter-mapping> <filter-name>encoder</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
dispatcher-servlet.xml配置如下，也就是springmvc的配置，主要功能是
- sao描控制器上的注解，把他们加入springmvc容器
- <mvc:annotataion-driven/>启用默认的HandlerMapping，HandlerAdator,
- <mvc:interceptors>配置拦截器
- 配置视图解析器，这个功能更常用
<?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" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <context:component-scan base-package="com.houjun.controller"></context:component-scan> <mvc:annotation-driven></mvc:annotation-driven> </beans>
applicationContext.xml配置，这个是spring容器，能做的是太多了，我这里只是启用注解
<?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.houjun.pojo"></context:component-scan> </beans>
一个简单的控制器如下
package com.houjun.controller; import com.houjun.pojo.Student; import com.houjun.pojo.User; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.context.ConfigurableWebApplicationContext; import org.springframework.web.context.WebApplicationContext; import javax.servlet.http.HttpServletRequest; /** * @Author: HouJun * @Date: 2019/11/8 15:21 * @Description: com.houjun.controller * @version: 1.0 */ @Controller @RequestMapping("/student") public class StudentController { @Autowired private Student student; @Autowired private ApplicationContext applicationContext; @Autowired private ConfigurableWebApplicationContext configurableWebApplicationContext; @RequestMapping("/hello") public String hello() { System.out.println("自动注入"+student); System.out.println("className"+applicationContext.getClass().getName()); String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames(); for (String beanDefinitionName : beanDefinitionNames) { System.out.println(beanDefinitionName); } System.out.println("--------------------------------------------------------------------------------------"); System.out.println("className"+configurableWebApplicationContext.getClass().getName()); String[] beanDefinitionNames1 = configurableWebApplicationContext.getBeanDefinitionNames(); for (String s : beanDefinitionNames1) { System.out.println(s); } return "/success.jsp"; } }
拦截器类，拦截器需要实现一个接口 HandlerInterceptorAdapter,可以有多个拦截器，拦截顺序以xml文件配置顺序为准，代码如下
package com.houjun.inerceptor; import org.springframework.web.servlet.ModelAndView; import org.springframework.web.servlet.handler.HandlerInterceptorAdapter; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * @Author: HouJun * @Date: 2019/11/11 9:58 * @Description: com.houjun.inerceptor * @version: 1.0 */ public class UserInterceptor extends HandlerInterceptorAdapter { @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println("自定义拦截器1，进入控制器之前"); return true; } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println("自定义拦截器1，控制器之后，进入视图之前"); } @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { System.out.println("自定义拦截器1，控制器之后，进入视图之后"); } }
目录结构
有了这些东西，就能启动一个web项目了，需要注意的是，配置Project Stucture -->Libraries和Tomcat容器之时可能会有各种问题，不过慢慢来，一点一点就是知道配置这些的含义了。
