log4j-1.x之三【普通web项目中的高级应用MDC】

今天药忘吃喽~ 2022-09-27 06:21 94阅读 0赞

这篇文章http://blog.csdn.net/rainyspring4540/article/details/60768437  只是简单纯净的web配置，无任何框架，其他日志的整合

一般web项目，用户权限一般存储在session级别，用户的每个请求在request级别，如果项目要实现将request级别或session级别的参数统一插入日志中，而无需在每个servlet中单独在日志中写入该参数，那就需要filter了，结合log4j的MDC类即可实现

![20170307183155202][]

log4j配置和普通的web项目相同，注意以上中通过日志你会发现，多出来很多信息，比如访问的url和session的参数信息，那些就是通过filter实现的，下面看看filter：

package filter;
    
    import java.io.IOException;
    
    import javax.servlet.Filter;
    import javax.servlet.FilterChain;
    import javax.servlet.FilterConfig;
    import javax.servlet.ServletException;
    import javax.servlet.ServletRequest;
    import javax.servlet.ServletResponse;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpSession;
    
    import org.apache.log4j.MDC;
    
    public class Log4jMDCFilter implements Filter {
    
    
    	@Override
    	public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)
    			throws IOException, ServletException {
    
    		try {
    			HttpServletRequest request = (HttpServletRequest) req;
    			// 获取请求路径
    			String requestURL = request.getRequestURI();
    			if (request.getQueryString()!=null && !request.getQueryString().equals("")) {
    				requestURL = requestURL + "?" + request.getQueryString();
    			}
    			//request信息
    			MDC.put("url", requestURL);
    
    			HttpSession session = request.getSession();
    			if (session != null) {
    				//session信息
    				MDC.put("userId", "你自己的session信息");
    			} 
    			//插入一条系统日志
    			chain.doFilter(request, resp);
    		} catch (Exception e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		} finally {
    			MDC.clear();//防止内存溢出。要实时清空
    		}
    	}
    
    	@Override
    	public void init(FilterConfig arg0) throws ServletException {
    		// TODO Auto-generated method stub
    
    	}
    
    	@Override
    	public void destroy() {
    		// TODO Auto-generated method stub
    		
    	}
    }

fiter是要在web.xml中配置的：

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
      <display-name>C</display-name>
      <filter>
        <filter-name>Log4jMDCUserFilter</filter-name>
        <filter-class>filter.Log4jMDCFilter</filter-class>
      </filter>
      <filter-mapping>
        <filter-name>Log4jMDCUserFilter</filter-name>
        <url-pattern>*</url-pattern>
      </filter-mapping>ni
    
      <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
      </welcome-file-list>
    </web-app>

贴下log4j.properties:

##log4j.properties
    log4j.rootLogger=info,stdout,logfile
    
    
    #-------------stdout------------
    log4j.appender.stdout=org.apache.log4j.ConsoleAppender
    #log4j.appender.db.Threshold=info
    log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
    log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd hh:mm:ss} %p [%c] %X{url} <%m> %X{userId}%n
    
    #-------------logfile------------
    log4j.appender.logfile=org.apache.log4j.DailyRollingFileAppender
    log4j.appender.logfile.Append=true
    log4j.appender.logfile.DatePattern='.'yyyy-MM-dd
    log4j.appender.logfile.File=d:/bb/sys.log
    log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
    log4j.appender.logfile.layout.ConversionPattern=%d{yyyy-MM-dd hh:mm:ss} %p [%c] %X{url} <%m> %X{userId}%n

你会发现在过滤器中，代码

MDC.put("url", requestURL);
     MDC.put("userId", "你自己的session信息");
     
    和在log4j中日志的%X{url}、%X{userId}是对应的，必须这么写

[20170307183155202]: /images/20220708/7b1bd1ea7cb6405e8075566fa39ef0c9.png