------------吾亦无他,唯手熟尔，谦卑若愚，好学若饥-------------
拦截器Interceptor:
对处理方法进行双向的拦截，可以对其做日志记录等
我选择的是实现HandlerInterceptor接口
我把执行流程放上来，单个拦截器的和多个拦截器的，然后写个Demo案例，就可以正式结束Springmvc，过几天写完SSM整合，SSM就结束了，将来有机会多放几个项目在博客园上
图1，单个拦截器执行流程
图2，多个拦截器的执行流程
我会给大家定义俩个拦截器，大家跑一下，看看执行顺序，另外大家可以举一反三的扩充，定义多个拦截器或者在拦截器的方法中填实际的处理代码
案例Demo开始
1.自定义第一个拦截器FirstInterceptor
package cn.dawn.day25interceptor;/** * Created by dawn on 2018-04-02. */ import org.springframework.web.servlet.HandlerInterceptor; import org.springframework.web.servlet.ModelAndView; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class FirstInterceptor implements HandlerInterceptor{ //在Handler执行前执行 public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception { System.out.println("preHandle============="); return true; } public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception { System.out.println("postHandle============="); } public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception { System.out.println("afterCompletion============="); } }
preHandle这个方法，它的返回值决定了下面俩个方法是否执行，如果false，则不会执行下面的那俩方法
2.自定义第二个拦截器SecondInterceptor
package cn.dawn.day25interceptor;/** * Created by dawn on 2018-04-02. */ import org.springframework.web.servlet.HandlerInterceptor; import org.springframework.web.servlet.ModelAndView; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class SecondInterceptor implements HandlerInterceptor { public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception { System.out.println("Second preHandle============="); return true; } public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception { System.out.println("Second postHandle============="); } public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception { System.out.println("Second afterCompletion============="); } }
3.自定义处理器和处理方法
package cn.dawn.day25interceptor;/** * Created by dawn on 2018-04-02. */ import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; @Controller public class FirstController { @RequestMapping("/first") public String doFirst(){ System.out.println("Handler method"); return "success"; } }
4.自己的xml配置文件中配置一道，将拦截器配置上去
<?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:mvc="http://www.springframework.org/schema/mvc" 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/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"> <!--包扫描器--> <context:component-scan base-package="cn.dawn.day25interceptor"></context:component-scan> <!--视图解析器--> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/day25/"></property> <property name="suffix" value=".jsp"></property> </bean> <!--拦截器配置--> <mvc:interceptors> <!--配置多个拦截器，多个拦截器链--> <mvc:interceptor> <mvc:mapping path="/**"/> <bean class="cn.dawn.day25interceptor.FirstInterceptor"></bean> </mvc:interceptor> <mvc:interceptor> <mvc:mapping path="/**"/> <bean class="cn.dawn.day25interceptor.SecondInterceptor"></bean> </mvc:interceptor> </mvc:interceptors> <!--绑定注解驱动--> <mvc:annotation-driven></mvc:annotation-driven> </beans>
此处的拦截器位置的前后，决定了他们执行的先后
此处的/**表示任意多级目录的任意方法，全部的意思
5.修改web.xml的中央调度器的上下文配置位置为上面那个xml
6.jsp页面，我不是return了个success么，所以建一个success.jsp
<%-- Created by IntelliJ IDEA. User: Dawn Date: 2018/4/2 Time: 14:19 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %> <html> <head> <title>成功</title> </head> <body> <h1>SUCCESS</h1> </body> </html>
7.启动tomcat，访问处理器的那个处理方法/first
