Log4j MDC使用案例

import java.io.IOException;import java.util.Map;import java.util.UUID;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.commons.lang.StringUtils;import org.apache.log4j.MDC;import org.springframework.web.filter.OncePerRequestFilter;/** * 存放在MDC中的数据，log4j可以直接引用并作为日志信息打印出来. *  * 
 * 示例使用: * log4j.appender.stdout.layout.conversionPattern=%d [%X{loginUserId}/%X{req.remoteAddr}/%X{req.id} - %X{req.requestURI}?%X{req.queryString}] %-5p %c{2} - %m%n * 
 * @author badqiu */public class LoggerMDCFilter extends OncePerRequestFilter implements Filter{        protected void doFilterInternal(HttpServletRequest request,HttpServletResponse response, FilterChain chain)throws ServletException,IOException {        try {            //示例为一个固定的登陆用户,请直接修改代码            MDC.put("loginUserId", "demo-loginUsername");                        MDC.put("req.requestURI", StringUtils.defaultString(request.getRequestURI()));            MDC.put("req.queryString", StringUtils.defaultString(request.getQueryString()));            MDC.put("req.requestURIWithQueryString", request.getRequestURI() + (request.getQueryString() == null ? "" : "?"+request.getQueryString()));            MDC.put("req.remoteAddr", StringUtils.defaultString(request.getRemoteAddr()));                        //为每一个请求创建一个ID，方便查找日志时可以根据ID查找出一个http请求所有相关日志            MDC.put("req.id", StringUtils.remove(UUID.randomUUID().toString(),"-"));             chain.doFilter(request, response);        }finally {            clearMDC();        }    }    private void clearMDC() {        Map map = MDC.getContext();        if(map != null) {            map.clear();        }    }}

log4j.properties

log4j.appender.logfile.layout.ConversionPattern=%X{userId} %d{yyyy-MM-dd HH:mm:ss} %p %l %m