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。