[Java知识库]SpringMVC -SpringMVC拦截器详解与案例

SpringMVC拦截器

拦截器（interceptor）的作用

拦截器和过滤器的区别

一般Spring或SpringMVC项目用Interceptor

SpringMVC拦截器入门案例

新建项目

new -> module

导入坐标

<dependencies>
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.32</version>
  </dependency>

  <dependency>
    <groupId>c3p0</groupId>
    <artifactId>c3p0</artifactId>
    <version>0.9.1.2</version>
  </dependency>

  <dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.10</version>
  </dependency>

  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>5.0.5.RELEASE</version>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-test</artifactId>
    <version>5.0.5.RELEASE</version>
  </dependency>

  <dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.0.1</version>
    <scope>provided</scope>
  </dependency>

  <dependency>
    <groupId>javax.servlet.jsp</groupId>
    <artifactId>javax.servlet.jsp-api</artifactId>
    <version>2.2.1</version>
    <scope>provided</scope>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>5.0.5.RELEASE</version>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.0.5.RELEASE</version>
  </dependency>

  <dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.9.0</version>
  </dependency>

  <dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.0</version>
  </dependency>

  <dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.9.0</version>
  </dependency>

  <dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.1</version>
  </dependency>

  <dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.3</version>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
    <version>5.0.5.RELEASE</version>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-tx</artifactId>
    <version>5.0.5.RELEASE</version>
  </dependency>
</dependencies>

<build>
<plugins>
  <plugin>
    <groupId>org.apache.tomcat.maven</groupId>
    <artifactId>tomcat7-maven-plugin</artifactId>
    <version>2.2</version>
  </plugin>
</plugins>
</build>

编写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
">

<!--    1.mvc注解驱动-->
    <mvc:annotation-driven/>

<!--    2.配置视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

<!--    3.静态资源权限开放-->
    <mvc:default-servlet-handler/>

<!--    4.组件扫描 扫描Controller-->
    <context:component-scan base-package="com.taotao.controller"/>

</beans>

编写web.xml

  <!--配置SpringMVC的前端控制器-->
  <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>

编写index.jsp

<%@page language="java"  contentType="text/html;charset=UTF-8" %>
<%@page isELIgnored="false"%>
<html>
<body>
<h2>Hello World!${name}</h2>
</body>
</html>

编写TargetController1类

package com.taotao.interceptor;

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

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

/**
 * create by 刘鸿涛
 * 2022/4/23 15:39
 */
@SuppressWarnings({"all"})
public class MyInterceptor1 implements HandlerInterceptor {
    //在目标方法执行之前 执行
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle...");
        return false;
    }

    //在目标方法执行之后 视图对象返回之前执行
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle...");
    }

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

成功测试

编写MyInterceptor类

package com.taotao.interceptor;

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

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

/**
 * create by 刘鸿涛
 * 2022/4/23 15:39
 */
@SuppressWarnings({"all"})
public class MyInterceptor implements HandlerInterceptor {
    //在目标方法执行之前 执行
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle...");
        return false;
    }

    //在目标方法执行之后 视图对象返回之前执行
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle...");
    }

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

编写Spring-mvc.xml

配置拦截器

<!--    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.taotao.interceptor.MyInterceptor1"/>
        </mvc:interceptor>
    </mvc:interceptors>

成功测试

preHandle方法

变更preHandle返回值为true

编写MyInterceptor1.java

package com.taotao.interceptor;

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

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

/**
 * create by 刘鸿涛
 * 2022/4/23 15:39
 */
@SuppressWarnings({"all"})
public class MyInterceptor1 implements HandlerInterceptor {
    //在目标方法执行之前 执行
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle...");
        return true;
    }

    //在目标方法执行之后 视图对象返回之前执行
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle...");
    }

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

成功测试

新建error视图

<%--
  Created by IntelliJ IDEA.
  User: guigui
  Date: 2022/4/23
  Time: 16:01
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>error!!</h1>
</body>
</html>

编写preHandle

编写MyInterceptor.java

package com.taotao.interceptor;

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

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

/**
 * create by 刘鸿涛
 * 2022/4/23 15:39
 */
@SuppressWarnings({"all"})
public class MyInterceptor1 implements HandlerInterceptor {
    //在目标方法执行之前 执行
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle...");
        String param = request.getParameter("param");
        if(param.equals("yes")){
            return true;    //返回true代表放行 false代表不放行
        }else{
            //跳转视图到error.jsp
            request.getRequestDispatcher("/error.jsp").forward(request,response);
            return false;
        }
    }

    //在目标方法执行之后 视图对象返回之前执行
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle...");
    }

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

成功测试

不带参数

参数非 yes

参数为yes

postHandle方法

编写postHandle

modelAndView.addObject("name","liuhongtao");

package com.taotao.interceptor;

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

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

/**
 * create by 刘鸿涛
 * 2022/4/23 15:39
 */
@SuppressWarnings({"all"})
public class MyInterceptor1 implements HandlerInterceptor {
    //在目标方法执行之前 执行
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle...");
        String param = request.getParameter("param");
        if("yes".equals(param)){
            return true;    //返回true代表放行 false代表不放行
        }else{
            //跳转视图到error.jsp
            request.getRequestDispatcher("/error.jsp").forward(request,response);
            return false;
        }
    }

    //在目标方法执行之后 视图对象返回之前执行
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        modelAndView.addObject("name","liuhongtao");
        System.out.println("postHandle...");
    }

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

成功测试

新建MyInterceptor2.java

编写MyInterceptro2.java

package com.taotao.interceptor;

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

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

/**
 * create by 刘鸿涛
 * 2022/4/23 15:39
 */
@SuppressWarnings({"all"})
public class MyInterceptor2 implements HandlerInterceptor {
    //在目标方法执行之前 执行
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle2222222...");
        return true;    //返回true代表放行 false代表不放行

    }

    //在目标方法执行之后 视图对象返回之前执行
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        modelAndView.addObject("name","liuhongtao");
        System.out.println("postHandle2222...");
    }

    //在流程都执行完毕后 执行
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion2222...");
    }
}

编写Spring-mvc.xml

<!--    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.taotao.interceptor.MyInterceptor1"/>
        </mvc:interceptor>

        <mvc:interceptor>
            <!--            对哪些资源执行拦截操作-->
            <mvc:mapping path="/**"/>
            <bean class="com.taotao.interceptor.MyInterceptor2"/>
        </mvc:interceptor>
    </mvc:interceptors>

成功测试

注意

拦截器执行先后顺序

1号拦截器先执行的原因，是因为xml配置拦截器的先后顺序

拦截器自我总结

鬼鬼骑士:
学完spring-mvc拦截器后关于我对“面向切面（AOP）”编程的简述：

鬼鬼骑士:
在一个类中编写流程代码可以轻松控制整个项目“开始”，“跳转”，“终止过程”，这个类叫做拦截器，我们仅仅需要在xml配置文件中开启或关闭此拦截器类，来确认是否应该应用此“过程”

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