Spring自定义一个拦截器类SomeInterceptor，实现HandlerInterceptor接口及其方法的实例

利用Spring的拦截器可以在处理器Controller方法执行前和后增加逻辑代码，了解拦截器中preHandle、postHandle和afterCompletion方法执行时机。

自定义一个拦截器类SomeInterceptor，实现HandlerInterceptor接口及其方法。

然后在spring-mvc.xml中添加拦截器配置，来指定拦截哪些请求。

步骤一： 创建SomeInterceptor拦截器组件

新建一个com.souvc.interceptor包，在该包中新建一个SomeInterceptor类。SomeInterceptor类要实现HandlerInterceptor接口及其约定方法，代码如下：

package com.souvc.interceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class SomeInterceptor implements HandlerInterceptor {
    public void afterCompletion(HttpServletRequest req,
            HttpServletResponse res, Object handller, Exception e)
            throws Exception {
        System.out.println("请求处理完成后调用");
    }

    public void postHandle(HttpServletRequest req, HttpServletResponse res,
            Object handller, ModelAndView mv) throws Exception {
        System.out.println("处理器执行后调用");
    }

    public boolean preHandle(HttpServletRequest req, HttpServletResponse res,
            Object handller) throws Exception {
        System.out.println("处理器执行前调用");
        return true;
    }
}

步骤二：修改spring-mvc.xml配置

打开工程src下的spring-mvc.xml文件，追加SomeInterceptor配置。

 <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/spring/*"/>
            <mvc:exclude-mapping path="/login/*"/>
            <bean class="com.souvc.interceptor.SomeInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

spring-mvc.xml 源码：

<?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:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:jee="http://www.springframework.org/schema/jee"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xmlns:util="http://www.springframework.org/schema/util"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="
            http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
            http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
            http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
            http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
            http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd
            http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">

    <util:properties id="jdbcProps" location="classpath:db.properties" />

    <context:component-scan base-package="com.souvc" />
    <!-- 视图处理 -->
    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

     <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/spring/*"/>
            <mvc:exclude-mapping path="/login/*"/>
            <bean class="com.souvc.interceptor.SomeInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

</beans>

步骤三： 创建控制器HelloController中添加控制台打印信息

创建HelloController,在execute方法增加控制台打印语句。

package com.souvc.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping("/spring")
public class HelloController {
    @RequestMapping("/hello.form")
    public String execute() throws Exception {
        System.out.println("执行HelloController");
        return "hello";
    }
}

在WebRoot目录下的jsp目录下添加hello.jsp页面：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">

    <title>My JSP ‘hello.jsp‘ starting page</title>

    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->

  </head>

  <body>
    hello<br>
  </body>
</html>

web.xml文件如下：

<?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">
    <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>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>*.form</url-pattern>
    </servlet-mapping>

</web-app>

步骤四：部署并访问工程

部署工程后启动Tomcat，在浏览器中输入地址http://localhost:8080/SpringValues/spring/hello.form，观察控制台输出结果。

处理器执行前调用
执行HelloController
处理器执行后调用
请求处理完成后调用