Spring MVC拦截器

单个拦截器

 需要我们定义的类继承HandlerInterceptor 变成自定义的拦截器

package cn.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class FirstInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        System.out.println("==============MyInterceptor.preHandle()");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        System.out.println("===============MyInterceptor.postHandle()");

    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        System.out.println("================MyInterceptor.afterCompletion()");

    }
}

　　在applicationContext.xml中配置

<?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:aop="http://www.springframework.org/schema/aop" 
    xmlns:tx="http://www.springframework.org/schema/tx" 
    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/aop http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        ">
     
   <!-- 配置包扫描器-->
       <context:component-scan base-package="cn.happy.interceptor"></context:component-scan>


    <!--配置拦截器-->
     <mvc:interceptors>
         <mvc:interceptor>
             <mvc:mapping path="/**" />
             <bean class="cn.happy.interceptor.FirstInterceptor"></bean>
         </mvc:interceptor>
     </mvc:interceptors>
</beans>

　　创建FirstController.java

@Controller
public class FirstController {
    @RequestMapping("/first.do")
     public String doFirst(){
         return "/index.jsp";
     }
}

　　web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <!--核心控制器-->
    <servlet>
        <servlet-name>sprigmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:applicationContext.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>sprigmvc</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>
</web-app>

流程图

多个拦截器

在单个拦截器的基础上多添加一个连接器类SFirstInterceptor.java

package cn.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class SecondInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        System.out.println("===second===========MyInterceptor.preHandle()");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        System.out.println("===second============MyInterceptor.postHandle()");

    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        System.out.println("===second=============MyInterceptor.afterCompletion()");

    }
}

　　更改applicationContext.xml陪置

<?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:aop="http://www.springframework.org/schema/aop" 
    xmlns:tx="http://www.springframework.org/schema/tx" 
    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/aop http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        ">
     
   <!-- 配置包扫描器-->
       <context:component-scan base-package="cn.happy.interceptor"></context:component-scan>


    <!--配置攔截器-->
     <mvc:interceptors>
         <mvc:interceptor>
             <mvc:mapping path="/**" />
             <bean class="cn.happy.interceptor.FirstInterceptor"></bean>
         </mvc:interceptor>
         <mvc:interceptor>
             <mvc:mapping path="/**" />
             <bean class="cn.happy.interceptor.SFirstInterceptor"></bean>
         </mvc:interceptor>
     </mvc:interceptors>
</beans>

　　多拦截器请求流程图

特别需要注意的是：

在配置了两个拦截器的情况下：第一个拦截器里面的preHandler()返回的是true并且第二个preHandler()返回false，会执行afterCompletion()块，原因是他已经实例化出来了这个拦截器，在执行完整个程序的时候，必须销亡。