SpringMVC框架05——拦截器

傷城~ 2023-07-04 14:27 74阅读 0赞

## 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">
    
        
        <context:component-scan base-package="com.interceptor.controller"></context:component-scan>
    
        
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            
            <property name="prefix" value="/"></property>
            
            <property name="suffix" value=".jsp"></property>
        </bean>
    
        
        <mvc:interceptors>
            <mvc:interceptor>
                
                <mvc:mapping path="/**"/>
                
                <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：

![480452-20190315230050555-280660467.png][]

控制台输出结果：

![480452-20190315230112062-451771834.png][]

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：

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

<mvc:interceptors>
        
        <mvc:interceptor>
            <mvc:mapping path="/**"/>
            <bean class="com.interceptor.controller.TestInterceptor1"></bean>
        </mvc:interceptor>
        
        <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：

![480452-20190315230332797-888499328.png][]

控制台显示结果：

![480452-20190315230357134-1161397630.png][]

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。

[480452-20190315230050555-280660467.png]: https://img2018.cnblogs.com/blog/480452/201903/480452-20190315230050555-280660467.png
[480452-20190315230112062-451771834.png]: https://img2018.cnblogs.com/blog/480452/201903/480452-20190315230112062-451771834.png
[480452-20190315230332797-888499328.png]: https://img2018.cnblogs.com/blog/480452/201903/480452-20190315230332797-888499328.png
[480452-20190315230357134-1161397630.png]: https://img2018.cnblogs.com/blog/480452/201903/480452-20190315230357134-1161397630.png