基于SpringBoot+logback+MDC使用拦截器实现日志输出里为每个请求设置唯一请求ID

1.MDC#

MDC为“Mapped Diagnostic Context”（映射诊断上下文），即将一些运行时的上下文数据通过logback打印出来；此时我们需要借助org.sl4j.MDC类。

MDC类基本原理其实非常简单，其内部持有一个InheritableThreadLocal实例，用于保存context数据，MDC提供了put/get/remove等几个核心接口，用于操作ThreadLocal中的数据；ThreadLocal中的K-V，可以在logback.xml中声明，最终将会打印在日志中。

在使用MDC时需要注意一些问题，这些问题通常也是ThreadLocal引起的，比如我们需要在线程退出之前清除（clear）MDC中的数据；在线程池中使用MDC时，那么需要在子线程退出之前清除数据；可以调用MDC.remove()方法

2.使用#

• SpringBoot默认日志组件就是logback，无需导入jar包

• logback.xml配置 主要是 %X{requestId}

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  <?xml version="1.0" encoding="UTF-8"?>
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  <configuration>
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      <!--日志文件轮询 每天一个日志文件-->
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      <appender name="File" class="ch.qos.logback.core.rolling.RollingFileAppender">
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          <Append>true</Append>
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          <File>../logs/platform_logs/platformHome-api.log</File>
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          <encoder>
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              <pattern>%d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] [%X{requestId}] - [ %p ] %m%n</pattern>
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          </encoder>
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          <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
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              <fileNamePattern>../logs/xxxxxxx.log.%d{-yyyy-MM-dd}</fileNamePattern>
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          </rollingPolicy>
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      </appender>
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      <!--本地控制台输出-->
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      <appender name="Console" class="ch.qos.logback.core.ConsoleAppender">
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          <Target>System.out</Target>
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          <encoder>
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              <pattern>%d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] [%X{requestId}] - [ %p ] %m%n</pattern>
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          </encoder>
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      </appender>
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      <root level="INFO">
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          <appender-ref ref="File"/>
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          <appender-ref ref="Console"/>
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      </root>
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  </configuration>

  展开收起

• 拦截器

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  @Slf4j
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  public class LogInterceptor implements HandlerInterceptor {
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      private final static String REQUEST_ID = "requestId";
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      private final static String REQUEST_TIME = "requestTime";
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      @Override
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      public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) {
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          String ipAddress = IPAddressUtils.getIPAddress(httpServletRequest);
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          String url = httpServletRequest.getRequestURL().toString();
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          SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
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          String requestTime = sdf.format(new Date());
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          String uuid = UUID.randomUUID().toString().replaceAll("-", "");
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          log.info("请求的url:{}  客户端IP为:{}  设置的请求Id为:{} 请求时间为:{}", url, ipAddress, uuid, requestTime);
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          log.info("put requestId ({}) requestTime ({}) to logger", uuid, requestTime);
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          MDC.put(REQUEST_ID, uuid);
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          MDC.put(REQUEST_TIME, requestTime);
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          return true;
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      }
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      @Override
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      public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) {
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          String uuid = MDC.get(REQUEST_ID);
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          String requestTime = MDC.get(REQUEST_TIME);
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          MDC.remove(REQUEST_ID);
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          MDC.remove(REQUEST_TIME);
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          log.info("remove requestId ({}) requestTime ({}) from logger", uuid, requestTime);
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      }
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      @Override
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      public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) {
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      }
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  }

  展开收起

• 注册拦截器

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  @Configuration
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  public class WebMvcConfig implements WebMvcConfigurer {
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      @Override
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      public void addInterceptors(InterceptorRegistry registry) {
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          registry.addInterceptor(logInterceptor());
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      }
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      @Bean
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      public LogInterceptor logInterceptor() {
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          return new LogInterceptor();
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      }
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  }

3.效果#

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