0%

MDC日志跟踪

MDC日志跟踪

MDC是log4j,logback和java.util.logging中提供的一种方便在多线程下记录日志的功能,全称是Mapped Diagnostic Context,可以看做是一个与当前线程绑定的哈希表,依赖于ThreadLocalMap

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
public class LogInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
//如果有上层调用就用上层的ID
String traceId = request.getHeader("traceId");
if (traceId == null) {
traceId = TraceIdUtil.getTraceId();
}

MDC.put("traceId", traceId);
return true;
}

@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
throws Exception {
}

@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
//调用结束后删除
MDC.remove("traceId");
}
}

在配置日志格式时,使用%X{}来获取MDC中的值

1
<PatternLayout charset="UTF-8" pattern="[%-5p %d{yyyy-MM-dd HH:mm:ss.SSS} [%X{traceId}]] %l [%m]%n"/>