log4j2配置固定内容(IP等)

需求： 记录日志时需要添加服务IP和服务编号(由UUID生成)，便于运维人员在查看日志时定位到哪台服务器上的哪个服务。

基于spring web项目

1、 log4j2.xml文件

<Configuration status="error" monitorInterval="30">

    <Properties>
        
        <Property name="LOG_HOME">/home/logsProperty>
    Properties>
    <Appenders>
        <Console name="CONSOLE" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} %-5level %class{1.}:%L - IP:%X{ip}&ID:%X{UUID}  %msg%xEx%n" />
        Console>
        
        <RollingFile name="FILE" fileName="${LOG_HOME}/demo.log"
            filePattern="${LOG_HOME}/demo.log.%d{yyyy-MM-dd}.log.gz">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} %-5level %class{1.}:%L - %X{ip}&ID:%X{UUID}  %msg%xEx%n" />
            <Policies>
                
                <TimeBasedTriggeringPolicy modulate="true"
                    interval="24" />
                <SizeBasedTriggeringPolicy size="128KB" />
            Policies>
            
            <DefaultRolloverStrategy max="10" />
        RollingFile>
    Appenders>
    <Loggers>

        
            
        

        <Root level="info">
            <AppenderRef ref="CONSOLE" />
            <AppenderRef ref="FILE">AppenderRef>
        Root>
    Loggers>
Configuration>

pattern格式配置
%d{yyyy-MM-dd HH:mm:ss.SSS} “d”, “date” 时间格式
%-5level “p”, “level” 输出日志级别，-5表示左对齐并且固定输出5个字符，如果不足在右边补0
%class{1.} “C”, “class” 类名，包名只有1位
%C{3} 获取类名前3级目录(包含类名)
%L “L”, “line” 输出行号
%M “M”, “method” 输出所在方法名
%m “m”, “msg”, “message” 日志文本
%xEx “xEx”, “xThrowable”, “xException” ExtendedThrowablePatternConverter
“ex”, “throwable”, “exception” ThrowablePatternConverter
“rEx”, “rThrowable”, “rException” RootThrowablePatternConverter
%n 换行

其他占位符有(部分)：
%l “l”, “location” 输出语句所在的行数, 包括类名、方法名、文件名、行数 例如：hahaha.Log4j2Test.main(Log4j2Test.java:15)
%T “T”, “tid”, “threadId” 输出线程ID
%t “t”, “tn”, “thread”, “threadName” 输出当前线程名称
%tp “tp”, “threadPriority” 输出线程权级
%F “F”, “file” 输出所在的类文件名，如Log4j2Test.java
%logger “c”, “logger” 输出logger名称，LogManager.getLogger(Log4j2Test.class);中的名称，此处是hahaha.Log4j2Test
%N “N”, “nano” 纳秒
%sn “sn”, “sequenceNumber” 日志计数(全局)
%u “u”, “uuid” UUID(全局)
%X{ip} “X”, “mdc”, “MDC” MDC方式获取ip(等同于 %MDC{ip} 和 %mdc{ip} )
%x “x”, “NDC” NDC方式

2、 过滤器类
log4j2中用ThreadContext代替MDC

package demo;

import org.apache.logging.log4j.ThreadContext;

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 java.io.IOException;

public class ThreadContextFilter implements Filter {


    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        try {
            ThreadContext.put("UUID", StaticUUID.ID);    //StaticUUID是自己写的类，用于生成UUID常量。
            ThreadContext.put("ip", request.getLocalAddr());
            chain.doFilter(request, response);
        } finally {
        //清除ThreadContext,避免内存泄露
            ThreadContext.clearAll();
        }
    }

    @Override
    public void destroy() {

    }

}

3、 web.xml

<web-app>
    <display-name>Archetype Created Web Applicationdisplay-name>

    <filter>
        <filter-name>log4jFilterfilter-name>
        <filter-class>demo.ThreadContextFilterfilter-class>
    filter>
    <filter-mapping>
        <filter-name>log4jFilterfilter-name>
        <url-pattern>/*url-pattern>
    filter-mapping>
    <servlet>
        <servlet-name>log4j2demoservlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
        <init-param>
            <param-name>contextConfigLocationparam-name>
            <param-value>classpath:applicationContext.xmlparam-value>
        init-param>
        <load-on-startup>1load-on-startup>
    servlet>
    <servlet-mapping>
        <servlet-name>log4j2demoservlet-name>
        <url-pattern>/url-pattern>
    servlet-mapping>

    <welcome-file-list>
        <welcome-file>index.htmlwelcome-file>
        <welcome-file>index.htmwelcome-file>
        <welcome-file>index.jspwelcome-file>
        <welcome-file>default.htmlwelcome-file>
        <welcome-file>default.htmwelcome-file>
        <welcome-file>default.jspwelcome-file>
    welcome-file-list>
web-app>

4、 Hello类测试

package demo;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;


@Controller
public class Hello {
    public static Logger logger = LogManager.getLogger();

    @RequestMapping("/hello")
    public void hello(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        logger.info("hello");
        request.getRequestDispatcher("index.jsp").forward(request, response);
    }
}

测试结果(多次刷新页面)
2017-06-28 21:04:59.013 INFO d.Hello:22 - IP:0:0:0:0:0:0:0:1&trace ID:5ba23654bc104e8b8019963084f16cb8 hello

2017-06-28 21:06:48.364 INFO d.Hello:22 - IP:0:0:0:0:0:0:0:1&trace ID:5ba23654bc104e8b8019963084f16cb8 hello

2017-06-28 21:06:49.203 INFO d.Hello:22 - IP:0:0:0:0:0:0:0:1&trace ID:5ba23654bc104e8b8019963084f16cb8 hello

2017-06-28 21:06:49.900 INFO d.Hello:22 - IP:0:0:0:0:0:0:0:1&trace ID:5ba23654bc104e8b8019963084f16cb8 hello
其中IP:0:0:0:0:0:0:0:1等同于127.0.0.1，由于是本地访问，就会出现这个值。用别的机器访问就会正常。