springMVC中的拦截器的使用

首先先上结构图

接下来是代码.
MyController.java

package com.mi.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.servlet.mvc.multiaction.MultiActionController;@Controllerpublic class MyController extends MultiActionController{    @RequestMapping("add")    public String add(){        System.out.println("add");        return "success";    }}

MyIntereptor.java 拦截器类

package com.mi.intereptor;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.web.servlet.HandlerInterceptor;import org.springframework.web.servlet.ModelAndView;public class MyIntereptor implements HandlerInterceptor{    public void afterCompletion(HttpServletRequest arg0,            HttpServletResponse arg1, Object arg2, Exception arg3)            throws Exception {    }    public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1,            Object arg2, ModelAndView arg3) throws Exception {    }    public boolean preHandle(HttpServletRequest request, HttpServletResponse response,            Object arg2) throws Exception {        String id = request.getParameter("id");        if ("1".equals(id)) {            System.out.println("拦截了");            response.sendRedirect("error.jsp");            return false;        }        return true;    }}

SpringMVC-servlet.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"    xmlns:mvc="http://www.springframework.org/schema/mvc"    xmlns:context="http://www.springframework.org/schema/context"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="        http://www.springframework.org/schema/beans        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd        http://www.springframework.org/schema/mvc        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd        http://www.springframework.org/schema/context        http://www.springframework.org/schema/context/spring-context-3.0.xsd">    <!-- 开启mvc注解 -->    <mvc:annotation-driven/>    <!-- 开启扫描 -->    <context:component-scan base-package="com.mi.*"></context:component-scan>    <!-- 加载静态文件 -->    <mvc:resources location="/resource/" mapping="/resource/**"/>       <!-- 拦截器 -->    <mvc:interceptors>        <mvc:interceptor>            <mvc:mapping path="/add"/>            <bean class="com.mi.intereptor.MyIntereptor"></bean>        </mvc:interceptor>    </mvc:interceptors>    <!-- 配置视图解析器 -->    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"></property>        <property name="prefix" value="/"></property>        <property name="suffix" value=".jsp"></property>    </bean></beans>

web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5"     xmlns="http://java.sun.com/xml/ns/javaee"     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  <display-name></display-name>   <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list>  <servlet>    <servlet-name>SpringMVC</servlet-name>    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>    <load-on-startup>1</load-on-startup>  </servlet>  <servlet-mapping>    <servlet-name>SpringMVC</servlet-name>    <url-pattern>/</url-pattern>  </servlet-mapping><!-- 设置字符编码 -->    <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></web-app>

在浏览器地址栏分别输入
http://localhost:8888/ZIntereptorDemo/add?id=2
http://localhost:8888/ZIntereptorDemo/add?id=1
将会进入到不同的界面.
过程：
拦截器中拿到地址栏传来的id值，进行判断。如果id=1，进行拦截，页面跳转至error.jsp。否则，不进行拦截，进入success.jsp界面。

需要注意的几点：

1. 拦截器需要实现implements HandlerInterceptor接口，或者继承extends HandlerInterceptorAdapter适配器。其实该适配器底层也是实现了HandlerInterceptor接口的。此处如果继承该适配器的话，就不用覆写HandlerInterceptor接口中的其他两个方法了，这两个方法用的不多，我们主要还是用public boolean preHandle方法。
2. 在搞定拦截器里面的东西之后，还需要让SpringMVC知道，所以要在SpringMVC-servlet.xml中进行配置：
   此处拦截的是/add打头的URL,还需要找到拦截器的位置。

拦截器<mvc:interceptors>        <mvc:interceptor>            <mvc:mapping path="/add"/>            <bean class="com.mi.intereptor.MyIntereptor"></bean>        </mvc:interceptor>    </mvc:interceptors>