通过ThreadLocal和HandlerInterceptor实现java后台业务埋点日志功能

目前公司的方案是用mdc来实现一个请求的业务数据埋点记录，但是mdc是map方式，需要手动设置key，而且每次都要手动clear，一是不方便管理，再者如果忘记clear会造成业务埋点数据混乱。所以有了想要把埋点数据字段统一封装的想法，这样方便维护，后面如果修改，也很容易找到所有修改点。于是我就想把封装好的bean放到mdc里，然后再用切面统一处理，但是，研究发现，mdc的value不支持object只能用String，很失望。我顺手翻了一下mdc的源码，如下

MDC的put方法源码
private InheritableThreadLocal<Map<String, String>> inheritableThreadLocal = new InheritableThreadLocal<Map<String, String>>() {
    protected Map<String, String> childValue(Map<String, String> parentValue) {
      return parentValue == null?null:new HashMap(parentValue);
    }
  };

  public BasicMDCAdapter() {
  }

  public void put(String key, String val) {
    if(key == null) {
      throw new IllegalArgumentException("key cannot be null");
    } else {
      Map<String, String> map = (Map)this.inheritableThreadLocal.get();
      if(map == null) {
        map = new HashMap();
        this.inheritableThreadLocal.set(map);
      }

      ((Map)map).put(key, val);
    }
  }

发现是用ThreadLocal实现的，它直接把里面的对象定义成map，我想，那我是不是可以定义成我自己的日志实体，开始动手，写了一个简单的类，如下

public class BusinessLogUtil {

  private final static ThreadLocal threadLocal = new InheritableThreadLocal<>();

  public static BusinessLog getThreadLocalLog() {
    if (threadLocal.get() == null) {
      return new BusinessLog();
    }
    return threadLocal.get();
  }

  public static void setThreadLocalLog(final BusinessLog businessLog) {
    threadLocal.set(businessLog);
  }

  public static void remove() {
    threadLocal.remove();
  }
}

好了，操作类实现完了，来实现一下统一的前置和后置操作，刚开始用aspectj实现的，但是发现，不是在同一线程里操作的，具体原理不细说。于是换成HandlerInterceptor，具体代码如下

@Slf4j
public class BusinessLogInterceptor implements HandlerInterceptor {

  @Override
  public boolean preHandle(final HttpServletRequest httpServletRequest,
      final HttpServletResponse httpServletResponse, final Object o) throws Exception {
    final BusinessLog businessLog = new BusinessLog();
    businessLog.setUserId(String.valueOf(Math.random()));
    BusinessLogUtil.setThreadLocalLog(businessLog);
    log.info("开始访问：" + BusinessLogUtil.getThreadLocalLog().toString());
    return true;// 只有返回true才会继续向下执行，返回false取消当前请求
  }

  @Override
  public void postHandle(final HttpServletRequest httpServletRequest,
      final HttpServletResponse httpServletResponse, final Object o,
      final ModelAndView modelAndView)
      throws Exception {

  }

  @Override
  public void afterCompletion(final HttpServletRequest httpServletRequest,
      final HttpServletResponse httpServletResponse, final Object o, final Exception e)
      throws Exception {
    log.info("访问结束:" + BusinessLogUtil.getThreadLocalLog().toString());
    BusinessLogUtil.remove();
    log.info("清理结束:" + BusinessLogUtil.getThreadLocalLog().toString());
  }
}

测试结果如下

[2017-12-01T11:25:40,015] | INFO | com.aaa.interceptor.BusinessLogInterceptor.preHandle(BusinessLogInterceptor.java:23) | http-nio-8080-exec-1  开始访问：BusinessLog(userId=0.1528058009781007, type=null, message=null, phone=null)
[2017-12-01T11:25:40,033] | INFO | com.aaa.api.rest.IntegrateController.getIntegrateList(IntegrateController.java:70) | http-nio-8080-exec-1访问controller:BusinessLog(userId=0.1528058009781007, type=null, message=null, phone=null)
[2017-12-01T11:25:40,033] | INFO | com.aaa.api.rest.IntegrateController.getIntegrateList(IntegrateController.java:74) | http-nio-8080-exec-1 设置controller变量:BusinessLog(userId=0.1528058009781007, type=integrate, message=null, phone=null)
[2017-12-01T11:25:40,033] | INFO | com.aaa.service.impl.BaseServiceImpl.getBatchList(BaseServiceImpl.java:39) | http-nio-8080-exec-1  访问service:BusinessLog(userId=0.1528058009781007, type=integrate, message=null, phone=null)
[2017-12-01T11:25:40,034] | INFO | com.aaa.service.impl.BaseServiceImpl.getBatchList(BaseServiceImpl.java:43) | http-nio-8080-exec-1 设置service变量:BusinessLog(userId=0.1528058009781007, type=integrate, message=null, phone=18600732726)
[2017-12-01T11:25:41,024] | INFO | com.aaa.oplog.OpLogAspect.logEvent(OpLogAspect.java:75) | http-nio-8080-exec-1  EventParameter{source='com.aaa.api.rest.IntegrateController', level='INFO', name='获取整合请求列表', desc='', arguments='ListBatchRequest(batchId=null, batchNo=null, state=null, createPerson=null, updateTime=null, createTime=null, type=null, pageNum=1, pageSize=10)', message='', method='getIntegrateList', url='http://localhost:8080/api/online-tickets/v1/integrate'}
[2017-12-01T11:25:41,066] | INFO | com.aaa.interceptor.BusinessLogInterceptor.afterCompletion(BusinessLogInterceptor.java:39) | http-nio-8080-exec-1 访问结束:BusinessLog(userId=0.1528058009781007, type=integrate, message=null, phone=18600732726)
[2017-12-01T11:25:41,067] | INFO | com.aaa.interceptor.BusinessLogInterceptor.afterCompletion(BusinessLogInterceptor.java:41) | http-nio-8080-exec-1 清理结束:BusinessLog(userId=null, type=null, message=null, phone=null)
[2017-12-01T11:33:18,880] | INFO | com.aaa.interceptor.BusinessLogInterceptor.preHandle(BusinessLogInterceptor.java:23) | http-nio-8080-exec-3 开始访问：BusinessLog(userId=0.203277605749153, type=null, message=null, phone=null)
[2017-12-01T11:33:18,881] | INFO | com.aaa.api.rest.IntegrateController.getIntegrateList(IntegrateController.java:70) | http-nio-8080-exec-3 访问controller:BusinessLog(userId=0.203277605749153, type=null, message=null, phone=null)
[2017-12-01T11:33:18,882] | INFO | com.aaa.api.rest.IntegrateController.getIntegrateList(IntegrateController.java:74) | http-nio-8080-exec-3 设置controller变量:BusinessLog(userId=0.203277605749153, type=integrate, message=null, phone=null)
[2017-12-01T11:33:18,882] | INFO | com.aaa.service.impl.BaseServiceImpl.getBatchList(BaseServiceImpl.java:39) | http-nio-8080-exec-3 访问service:BusinessLog(userId=0.203277605749153, type=integrate, message=null, phone=null)
[2017-12-01T11:33:18,882] | INFO | com.aaa.service.impl.BaseServiceImpl.getBatchList(BaseServiceImpl.java:43) | http-nio-8080-exec-3 设置service变量:BusinessLog(userId=0.203277605749153, type=integrate, message=null, phone=18600732726)
[2017-12-01T11:33:18,925] | INFO | com.aaa.oplog.OpLogAspect.logEvent(OpLogAspect.java:75) | http-nio-8080-exec-3  EventParameter{source='com.aaa.api.rest.IntegrateController', level='INFO', name='获取整合请求列表', desc='', arguments='ListBatchRequest(batchId=null, batchNo=null, state=null, createPerson=null, updateTime=null, createTime=null, type=null, pageNum=1, pageSize=10)', message='', method='getIntegrateList', url='http://localhost:8080/api/online-tickets/v1/integrate'}
[2017-12-01T11:33:18,931] | INFO | com.aaa.interceptor.BusinessLogInterceptor.afterCompletion(BusinessLogInterceptor.java:39) | http-nio-8080-exec-3 访问结束:BusinessLog(userId=0.203277605749153, type=integrate, message=null, phone=18600732726)
[2017-12-01T11:33:18,931] | INFO | com.aaa.interceptor.BusinessLogInterceptor.afterCompletion(BusinessLogInterceptor.java:41) | http-nio-8080-exec-3  清理结束:BusinessLog(userId=null, type=null, message=null, phone=null)

发现没有问题，每次访问的数据可以在整个请求区间内保存，在访问结束后，被清理掉，不会影响其它请求。