Interceptor拦截器入门

拦截器基本概念

  • 拦截器（Interceptor）用于对URL请求进行前置/后置过滤
  • Interceptor与Filter用途相似，但实现方式不同
  • Interceptor底层就是基于Spring AOP面向切面编程实现

拦截器开发流程

  1. Maven依赖servlet-api

provided：只有在开发和编译阶段才会引用，打包的时候会被排除在外

pom.xml

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <project xmlns="http://maven.apache.org/POM/4.0.0"
  3.          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  5.     <modelVersion>4.0.0</modelVersion>
  7.     <groupId>com.imooc</groupId>
  8.     <artifactId>interceptor</artifactId>
  9.     <version>1.0-SNAPSHOT</version>
  11.     <repositories>
  12.         <repository>
  13.             <id>aliyun</id>
  14.             <name>aliyun</name>
  15.             <url>https://maven.aliyun.com/repository/public</url>
  16.         </repository>
  17.     </repositories>
  18.     <dependencies>
  19.         <dependency>
  20.             <groupId>org.springframework</groupId>
  21.             <artifactId>spring-webmvc</artifactId>
  22.             <version>5.1.9.RELEASE</version>
  23.         </dependency>
  25.         <dependency>
  26.             <groupId>com.fasterxml.jackson.core</groupId>
  27.             <artifactId>jackson-core</artifactId>
  28.             <version>2.9.9</version>
  29.         </dependency>
  30.         <dependency>
  31.             <groupId>com.fasterxml.jackson.core</groupId>
  32.             <artifactId>jackson-databind</artifactId>
  33.             <version>2.9.9</version>
  34.         </dependency>
  35.         <dependency>
  36.             <groupId>com.fasterxml.jackson.core</groupId>
  37.             <artifactId>jackson-annotations</artifactId>
  38.             <version>2.9.9</version>
  39.         </dependency>
  41. +        <dependency>
  42. +            <groupId>javax.servlet</groupId>
  43. +            <artifactId>javax.servlet-api</artifactId>
  44. +            <version>3.1.0</version>
  45. +            <scope>provided</scope>
  46. +        </dependency>
  48.         <dependency>
  49.             <groupId>ch.qos.logback</groupId>
  50.             <artifactId>logback-classic</artifactId>
  51.             <version>1.2.3</version>
  52.         </dependency>
  53.     </dependencies>
  54. </project>
  1. 实现HandlerInterceptor接口
  • preHandle - 前置执行处理，如果返回false，请求到此结束
  • postHandle - 目标资源已被Spring MVC框架处理
  • afterCompletion - 响应文本已经产生

src/main/java/com/song/resufutl/interceptor/MyInterceptor.java

  1. package com.imooc.restful.interceptor;
  3. import org.slf4j.Logger;
  4. import org.slf4j.LoggerFactory;
  5. import org.springframework.web.servlet.HandlerInterceptor;
  6. import org.springframework.web.servlet.ModelAndView;
  8. import javax.servlet.http.HttpServletRequest;
  9. import javax.servlet.http.HttpServletResponse;
  11. public class MyInterceptor implements HandlerInterceptor {
  12.     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
  13.         System.out.println(request.getRequestURL() + "-准备执行");
  14. //        response.getWriter().print("[]");
  15.         return true;
  16.     }
  18.     public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
  19.         System.out.println(request.getRequestURL() + "-目标处理成功");
  20.     }
  22.     public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
  23.         System.out.println(request.getRequestURL() + "-响应内容已产生");
  24.     }
  25. }
  1. applicationContext配置过滤地址

src/mian/resources/applicationContext.xml

 +   <mvc:interceptors>
 +       <mvc:interceptor>
 +           <mvc:mapping path="/**"/>
 +           <bean class="com.imooc.restful.interceptor.MyInterceptor"/>
 +       </mvc:interceptor>
 +   </mvc:interceptors>

“/**”代表拦截所有，bean代表使用哪个拦截器

Interceptor拦截器使用技巧

src/mian/resources/applicationContext.xml

    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/restful/**"/>
            <mvc:mapping path="/webapi/**"/>
            <mvc:exclude-mapping path="/**.ico"/>
            <mvc:exclude-mapping path="/**.jpg"/>
            <mvc:exclude-mapping path="/**.gif"/>
            <mvc:exclude-mapping path="/**.js"/>
            <mvc:exclude-mapping path="/**.css"/>
            <mvc:exclude-mapping path="/resources/**"/>
            <bean class="com.imooc.restful.interceptor.MyInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

image.png

开发用户流量拦截器

引入日志依赖

pom.xml

+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+            <version>1.2.3</version>
+        </dependency>

配置logback

src/main/resources/logback.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>[%thread] %d %level %logger{10} - %msg%n</pattern>
        </encoder>
    </appender>
    <appender name="accessHistoryLog" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>d:/logs/history.%d.log</fileNamePattern>
        </rollingPolicy>
        <encoder>
            <pattern>[%thread] %d %level %logger{10} - %msg%n</pattern>
        </encoder>
    </appender>
    <root level="debug">
        <appender-ref ref="console"/>
    </root>
    <logger name="com.imooc.restful.interceptor.AccessHistoryInterceptor"
            level="INFO" additivity="false">
        <appender-ref ref="accessHistoryLog"/>
    </logger>
</configuration>

设置拦截器

src/main/java/com/imooc/restful/interceptor/AccessHistoryInterceptor.java

package com.imooc.restful.interceptor;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.HandlerInterceptor;

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

public class AccessHistoryInterceptor implements HandlerInterceptor {
    private Logger logger = LoggerFactory.getLogger(AccessHistoryInterceptor.class);

    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        StringBuilder log = new StringBuilder();
        log.append(request.getRemoteAddr());
        log.append("|");
        log.append(request.getRequestURL());
        log.append("|");
        log.append(request.getHeader("user-agent"));
        logger.info(log.toString());
        return true;
    }
}

使用拦截器

src/main/resources/applicationContext.xml

+    <mvc:interceptors>
+        <mvc:interceptor>
+            <mvc:mapping path="/**"/>
+            <mvc:exclude-mapping path="/resources/**"/>
+            <bean class="com.imooc.restful.interceptor.AccessHistoryInterceptor"/>
+        </mvc:interceptor>
+    </mvc:interceptors>

Spring MVC处理流程

image.png