基础框架 SpringMVC拦截器

矫情吗；* 2023-01-01 12:49 135阅读 0赞

## 基础框架 SpringMVC拦截器 ##

### SpringMVC拦截器概述 ###

Spring MVC 的处理器拦截器类似于 Servlet 开发中的过滤器 Filter，用于对处理器进行预处理和后处理。用户可以自己定义一些拦截器来实现特定的功能。
    
    谈到拦截器，还要向大家提一个词——拦截器链（Interceptor Chain）。
    拦截器链就是将拦截器按一定的顺序联结成一条链。在访问被拦截的方法或字段时，拦截器链中的拦截器就会按其之前定义的顺序被调用。
    
    拦截器与过滤器的区别：
    过滤器是 servlet 规范中的一部分， 任何 java web 工程都可以使用。
    拦截器是 SpringMVC 框架自己的，只有使用了 SpringMVC 框架的工程才能用。
    过滤器在 url-pattern 中配置了/*之后，可以对所有要访问的资源拦截，包括jsp，servlet等。
    拦截器它是只会拦截访问的控制器方法即Controller中的方法，如果访问的是 jsp， html,css,image 或者 js 是不会进行拦截的。
    
    它也是 AOP 思想的具体应用。
    我们要想自定义拦截器， 要求必须实现： HandlerInterceptor 接口。

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### 案例验证 ###

1.  项目结构  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzM3NTgzNjU1_size_16_color_FFFFFF_t_70 1]
2.  maven依赖

<?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>com.hello</groupId>
        <artifactId>springmvc_interceptor</artifactId>
        <version>1.0-SNAPSHOT</version>
        <packaging>war</packaging>
    
        <name>springmvc_interceptor Maven Webapp</name>
        
        <url>http://www.example.com</url>
    
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <maven.compiler.source>1.8</maven.compiler.source>
            <maven.compiler.target>1.8</maven.compiler.target>
            <spring.version>5.0.2.RELEASE</spring.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>${spring.version}</version>
            </dependency>
    
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-web</artifactId>
                <version>${spring.version}</version>
            </dependency>
    
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-webmvc</artifactId>
                <version>${spring.version}</version>
            </dependency>
    
            <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>servlet-api</artifactId>
                <version>2.5</version>
                <scope>provided</scope>
            </dependency>
    
            <dependency>
                <groupId>javax.servlet.jsp</groupId>
                <artifactId>jsp-api</artifactId>
                <version>2.0</version>
                <scope>provided</scope>
            </dependency>
        </dependencies>
    
        <build>
            <finalName>springmvc_day02_04_interceptor</finalName>
            <pluginManagement>
                <plugins>
                    <plugin>
                        <artifactId>maven-clean-plugin</artifactId>
                        <version>3.0.0</version>
                    </plugin>
                    
                    <plugin>
                        <artifactId>maven-resources-plugin</artifactId>
                        <version>3.0.2</version>
                    </plugin>
                    <plugin>
                        <artifactId>maven-compiler-plugin</artifactId>
                        <version>3.7.0</version>
                    </plugin>
                    <plugin>
                        <artifactId>maven-surefire-plugin</artifactId>
                        <version>2.20.1</version>
                    </plugin>
                    <plugin>
                        <artifactId>maven-war-plugin</artifactId>
                        <version>3.2.0</version>
                    </plugin>
                    <plugin>
                        <artifactId>maven-install-plugin</artifactId>
                        <version>2.5.2</version>
                    </plugin>
                    <plugin>
                        <artifactId>maven-deploy-plugin</artifactId>
                        <version>2.8.2</version>
                    </plugin>
                </plugins>
            </pluginManagement>
        </build>
    </project>

1.  web.xml

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" >
    
    <web-app>
      <display-name>Archetype Created Web Application</display-name>
    
      
      <filter>
        <filter-name>characterEncodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
          <param-name>encoding</param-name>
          <param-value>UTF-8</param-value>
        </init-param>
      </filter>
      <filter-mapping>
        <filter-name>characterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
      </filter-mapping>
    
      
      <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:springmvc.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>

1.  springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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">
    
        
        <context:component-scan base-package="com.hello"/>
    
        
        <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/pages/"/>
            <property name="suffix" value=".jsp"/>
        </bean>
    
        
        <mvc:resources location="/css/" mapping="/css/**"/>
        <mvc:resources location="/images/" mapping="/images/**"/>
        <mvc:resources location="/js/" mapping="/js/**"/>
    
        
        <mvc:interceptors>
            
            <mvc:interceptor>
                
                <mvc:mapping path="/user/*"/>
                
                
                <bean class="com.hello.interceptor.MyInterceptor1"/>
            </mvc:interceptor>
    
            
            <mvc:interceptor>
                
                <mvc:mapping path="/**"/>
                
                
                <bean class="com.hello.interceptor.MyInterceptor2"/>
            </mvc:interceptor>
        </mvc:interceptors>
    
        
        <mvc:annotation-driven/>
    
    </beans>

1.  Controller

/** * 异常测试 * * @author zrj * @date 2021/1/2 * @since V1.0 **/
    @Controller
    @RequestMapping("/user")
    public class UserController { 
        /** * 拦截器测试方法 */
        @RequestMapping("/testInterceptor")
        public String testInterceptor() { 
            System.out.println( "testInterceptor执行了..." );
            return "success";
        }
    
    }

1.  自定义拦截器

/** * 自定义拦截器 * * @author zrj * @date 2021/1/2 * @since V1.0 **/
    public class MyInterceptor1 implements HandlerInterceptor { 
    
        /** * 预处理，controller方法执行前 * return true 放行，执行下一个拦截器，如果没有，执行controller中的方法 * return false不放行 * * @param request * @param response * @param handler * @return * @throws Exception */
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { 
            System.out.println( "MyInterceptor1执行了...前1111" );
    
            // 这里可以直接跳转到指定页面，比如错误页面，可以提示您没有权限等
            // request.getRequestDispatcher("/WEB-INF/pages/error.jsp").forward(request,response);
            // return false；
    
            return true;
        }
    
        /** * 后处理方法，controller方法执行后，success.jsp执行之前 * * @param request * @param response * @param handler * @param modelAndView * @throws Exception */
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { 
            System.out.println( "MyInterceptor1执行了...后1111" );
            // request.getRequestDispatcher("/WEB-INF/pages/error.jsp").forward(request,response);
        }
    
        /** * success.jsp页面执行后，该方法会执行 * * @param request * @param response * @param handler * @param ex * @throws Exception */
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { 
            System.out.println( "MyInterceptor1执行了...最后1111" );
        }
    
    }

package com.hello.interceptor;
    
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /** * 自定义拦截器 * * @author zrj * @date 2021/1/2 * @since V1.0 */
    public class MyInterceptor2 implements HandlerInterceptor { 
    
        /** * 预处理，controller方法执行前 * return true 放行，执行下一个拦截器，如果没有，执行controller中的方法 * return false不放行 * * @param request * @param response * @param handler * @return * @throws Exception */
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { 
            System.out.println( "MyInterceptor2执行了...前2222" );
    
            // 这里可以直接跳转到指定页面，比如错误页面，可以提示您没有权限等
            // request.getRequestDispatcher("/WEB-INF/pages/error.jsp").forward(request,response);
            // return false；
            return true;
        }
    
        /** * 后处理方法，controller方法执行后，success.jsp执行之前 * * @param request * @param response * @param handler * @param modelAndView * @throws Exception */
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { 
            System.out.println( "MyInterceptor2执行了...后2222" );
            // request.getRequestDispatcher("/WEB-INF/pages/error.jsp").forward(request,response);
        }
    
        /** * success.jsp页面执行后，该方法会执行 * * @param request * @param response * @param handler * @param ex * @throws Exception */
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { 
            System.out.println( "MyInterceptor2执行了...最后2222" );
        }
    
    }

1.  jsp页面  
    index

<%--
      Created by IntelliJ IDEA.
      User: zrj
      Date: 2021/1/2
      Time: 16:58
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
        <title>index</title>
    </head>
    <body>
        <h3>拦截器</h3>
    
        <a href="user/testInterceptor" >拦截器</a>
    
    </body>
    </html>

error

<%--
      Created by IntelliJ IDEA.
      User: zrj
      Date: 2021/1/2
      Time: 16:58
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
    <html>
    <head>
        <title>Title</title>
    </head>
    <body>
    
        ${ errorMsg}
    
    </body>
    </html>

success

<%--
      Created by IntelliJ IDEA.
      User: zrj
      Date: 2021/1/2
      Time: 16:58
      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>
    
        <h3>执行成功</h3>
        <% System.out.println("success.jsp执行了..."); %>
    
    </body>
    </html>

执行结果
    
    MyInterceptor1执行了...前1111
    MyInterceptor2执行了...前2222
    testInterceptor执行了...
    MyInterceptor2执行了...后2222
    MyInterceptor1执行了...后1111
    success.jsp执行了...
    MyInterceptor2执行了...最后2222
    MyInterceptor1执行了...最后1111

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