SpringMVC框架05—

1、拦截器概述

Spring MVC的拦截器（Interceptor）与Java Servlet的过滤器（Filter）类似，它主要用于拦截用户的请求并做相应的处理，通常应用在权限验证、记录请求信息的日志、判断用户是否登录等功能上。

2、拦截器与过滤器的区别

拦截器是使用JDK动态代理实现的，拦截的是对应调用方法的拦截；
过滤器是使用Filter实现的，拦截的是request请求对象

3、定义单个拦截器

创建Controller类，代码如下：

@Controller

public class InterceptorController {

    @RequestMapping("/gotoTest")

    public String gotoTest(Model model){

        System.out.println("测试拦截器，控制器中gotoTest()方法执行。。。。");

        model.addAttribute("mess","拦截器测试！");

        return "test";

    }

}

创建拦截器类，代码如下：

public class TestInterceptor implements HandlerInterceptor {

    @Override

    public boolean preHandle(javax.servlet.http.HttpServletRequest httpServletRequest, javax.servlet.http.HttpServletResponse httpServletResponse, Object o) throws Exception {

        System.out.println("preHandle()......");

        return true;

    }

    @Override

    public void postHandle(javax.servlet.http.HttpServletRequest httpServletRequest, javax.servlet.http.HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) 
     throws Exception {

        System.out.println("postHandle()......");

    }

    @Override

    public void afterCompletion(javax.servlet.http.HttpServletRequest httpServletRequest, javax.servlet.http.HttpServletResponse httpServletResponse, Object o, Exception e) 
     throws Exception {

        System.out.println("afterCompletion()......");

    }

}

配置springmvc.xml文件：

<?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/context

       http://www.springframework.org/schema/context/spring-context.xsd

       http://www.springframework.org/schema/mvc

       http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd">

    <!--配置扫描控制器类-->

    <context:component-scan base-package="com.interceptor.controller"></context:component-scan>

    <!--配置视图解析器-->

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">

        <!--配置前缀-->

        <property name="prefix" value="/"></property>

        <!--配置后缀-->

        <property name="suffix" value=".jsp"></property>

    </bean>

    <!--配置拦截器-->

    <mvc:interceptors>

        <mvc:interceptor>

            <!--配置拦截路径-->

            <mvc:mapping path="/**"/>

            <!--不需要拦截的路径-->

            <mvc:exclude-mapping path="/login" />

            <bean class="com.demo.controller.TestExceptionController"></bean>

        </mvc:interceptor>

    </mvc:interceptors>

</beans>

创建视图文件test.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<%@ page isELIgnored="false" %>

<html>

<head>

    <title>测试拦截器</title>

</head>

<body>

    <p>视图：</p>

    <p>内容：${mess}</p>

</body>

</html>

测试结果，页面展示：

控制台输出结果：

在拦截器类TestInterceptor中实现了HandlerInterceptor接口，并重写了接口中的3个方法：

preHandle()方法：该方法在控制器的处理请求方法前执行，其返回值表示是否中断后续操作，返回true表示继续向下执行，返回false表示中断后续操作；
postHandle()方法：该方法在控制器的处理请求方法调用之后、解析视图之前执行，可以通过此方法对请求域中的模型和视图做进一步的修改；
afterCompletion()方法：该方法在控制器的处理请求方法执行完成后执行，即视图渲染结束后执行，可以通过此方法实现一些资源清理、记录日志信息等工作。

4、配置多个拦截器

创建Controller控制器类，代码如下：

@Controller

public class InterceptorController {

    @RequestMapping("/gotoTest")

    public String gotoTest(Model model){

        System.out.println("测试拦截器，控制器中gotoTest()方法执行。。。。");

        model.addAttribute("mess","拦截器测试！");

        return "test";

    }

}

创建多个拦截器类，
TestInterceptor1.java

public class TestInterceptor1 implements HandlerInterceptor {

    @Override

    public boolean preHandle(javax.servlet.http.HttpServletRequest httpServletRequest, javax.servlet.http.HttpServletResponse httpServletResponse, Object o) throws Exception {

        System.out.println("interceptor1......preHandle()......");

        return true;

    }

    @Override

    public void postHandle(javax.servlet.http.HttpServletRequest httpServletRequest, javax.servlet.http.HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) 
throws Exception {

        System.out.println("interceptor1......postHandle()......");

    }

    @Override

    public void afterCompletion(javax.servlet.http.HttpServletRequest httpServletRequest, javax.servlet.http.HttpServletResponse httpServletResponse, Object o, Exception e) 
throws Exception {

        System.out.println("interceptor1......afterCompletion()......");

    }

}

TestInterceptor2.java

public class TestInterceptor2 implements HandlerInterceptor {

    @Override

    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {

        System.out.println("interceptor2...preHandle().......");

        return true;

    }

    @Override

    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {

        System.out.println("interceptor2...postHandle().......");

    }

    @Override

    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {

        System.out.println("interceptor2...afterCompletion().......");

    }

}

在springmvc.xml中配置多个拦截器

<!--配置拦截器-->

<mvc:interceptors>

    <!--配置拦截器1-->

    <mvc:interceptor>

        <mvc:mapping path="/**"/>

        <bean class="com.interceptor.controller.TestInterceptor1"></bean>

    </mvc:interceptor>

    <!--配置拦截器2-->

    <mvc:interceptor>

        <mvc:mapping path="/gotoTest"/>

        <bean class="com.interceptor.controller.TestInterceptor2"></bean>

    </mvc:interceptor>

</mvc:interceptors>

测试结果，页面显示结果：

控制台显示结果：

在Web应用中通常需要配置多个拦截器同时工作，这时它们的preHandle方法按照配置文件中拦截器的配置顺序执行，而它们的postHandle方法和afterCompletion方法则按照配置顺序的反序执行。