SpringMVC拦截器

1.SpringMVC拦截器快速入门

1.pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>org.example</groupId>
  <artifactId>SpringMVC-interceptor</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>
  <dependencies>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>5.2.10.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>5.2.10.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.2.10.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>4.0.1</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.3.3</version>
    </dependency>
  </dependencies>
</project>

2.配置SpringMVC前端控制器

<?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_4_0.xsd"
         version="4.0">
  <!-- 配置SpringMVC前端控制器-->
  <display-name>Archetype Created Web Application</display-name>
  <servlet>
    <servlet-name>DispatcherServlet</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>DispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
</web-app>

3.spring-mvc.xml

<?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:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
       http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    <!-- mvc注解驱动-->
    <mvc:annotation-driven></mvc:annotation-driven>
    <!--配置内部资源视图解析器-->
    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>
   <!-- 静态资源权限开放-->
    <mvc:default-servlet-handler></mvc:default-servlet-handler>
   <!-- controller的组件扫描-->
    <context:component-scan base-package="com.study.controller"></context:component-scan>
    
   <!-- 配置拦截器-->
    <mvc:interceptors>
        <mvc:interceptor>
            <!--对哪些资源执行拦截操作-->
            <mvc:mapping path="/**"/>
            <bean class="com.study.interceptor.MyInterceptor"></bean>
        </mvc:interceptor>
    </mvc:interceptors>


</beans>

4.TargetController

package com.study.controller;

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

@Controller
public class TargetController { 
    @RequestMapping("/target")
    public ModelAndView show(){ 
        System.out.println("目标资源执行...");
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.addObject("name","rc");
        modelAndView.setViewName("index");
        return modelAndView;
    }

}

5.MyInterceptor

package com.study.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 MyInterceptor implements HandlerInterceptor { 
    //在目标方法执行之前执行
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { 
        System.out.println("preHandle...");
        return true; //返回true放行，false不放行
    }
    //在目标方法执行之后执行，视图对象返回之前执行
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { 
        System.out.println("postHandle...");

    }
    //流程都执行完毕之后执行
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { 
        System.out.println("afterCompletion...");

    }
}
/* preHandle... 目标资源执行... postHandle... afterCompletion... */

6.index.jsp

<html>
<body>
<h2>Hello World!${ name}</h2>
</body>
</html>

运行结果：