一、背景
最近因为公司项目性能需要，我们考虑把以前基于的log4j的日志系统重构成基于Slf4j和log4j2的日志系统，因为，使用slf4j可以很好的保证我们的日志系统具有良好的兼容性，兼容当前常见几种日志系统，而使用log4j2而不是log4j是因为Log4j 1.x 在高并发情况下出现死锁导致cpu使用率异常飙升，而Log4j2.0基于LMAX Disruptor的异步日志在多线程环境下性能会远远优于Log4j 1.x和logback（官方数据是10倍以上）。
关于slf4j的原理以及优点，请参见我的另一篇博客：slf4j介绍以及实现原理窥探
二、搭建步骤
1.依赖管理
1).删除项目中存在的Log4j1.x所必须的log4j和slf4j-log4j12等依赖。
可以到项目的根目录，执行：mvn dependency:tree > tree.log，之后使用 cat tree.log | grep log4j命令进行查找。
1 <exclusions> 2 <exclusion> 3 <groupId>org.slf4j</groupId> 4 <artifactId>slf4j-log4j12</artifactId> 5 </exclusion> 6 <exclusion> 7 <groupId>log4j</groupId> 8 <artifactId>log4j</artifactId> 9 </exclusion> 10 </exclusions>
2).添加以下slf4j和log4j2的依赖.
1 <!-- slf4j核心包--> 2 <dependency> 3 <groupId>org.slf4j</groupId> 4 <artifactId>slf4j-api</artifactId> 5 <version>1.7.13</version> 6 </dependency> 7 <dependency> 8 <groupId>org.slf4j</groupId> 9 <artifactId>jcl-over-slf4j</artifactId> 10 <version>1.7.13</version> 11 <scope>runtime</scope> 12 </dependency> 13 14 <!--核心log4j2jar包--> 15 <dependency> 16 <groupId>org.apache.logging.log4j</groupId> 17 <artifactId>log4j-api</artifactId> 18 <version>2.4.1</version> 19 </dependency> 20 <dependency> 21 <groupId>org.apache.logging.log4j</groupId> 22 <artifactId>log4j-core</artifactId> 23 <version>2.4.1</version> 24 </dependency> 25 <!--用于与slf4j保持桥接--> 26 <dependency> 27 <groupId>org.apache.logging.log4j</groupId> 28 <artifactId>log4j-slf4j-impl</artifactId> 29 <version>2.4.1</version> 30 </dependency> 31 <!--web工程需要包含log4j-web，非web工程不需要--> 32 <dependency> 33 <groupId>org.apache.logging.log4j</groupId> 34 <artifactId>log4j-web</artifactId> 35 <version>2.4.1</version> 36 <scope>runtime</scope> 37 </dependency> 38 39 <!--需要使用log4j2的AsyncLogger需要包含disruptor--> 40 <dependency> 41 <groupId>com.lmax</groupId> 42 <artifactId>disruptor</artifactId> 43 <version>3.2.0</version> 44 </dependency>
2.web.xml中设置log4j2的监听器和过滤器（servlet3.0及以上版本不需要该步操作）
1 <!--对于log4j2，Servlet2.5以前的版本需要--> 2 <listener> 3 <listener-class>org.apache.logging.log4j.web.Log4jServletContextListener</listener-class> 4 </listener> 5 <filter> 6 <filter-name>log4jServletFilter</filter-name> 7 <filter-class>org.apache.logging.log4j.web.Log4jServletFilter</filter-class> 8 </filter> 9 <filter-mapping> 10 <filter-name>log4jServletFilter</filter-name> 11 <url-pattern>/*</url-pattern> 12 <dispatcher>REQUEST</dispatcher> 13 <dispatcher>FORWARD</dispatcher> 14 <dispatcher>INCLUDE</dispatcher> 15 <dispatcher>ERROR</dispatcher> 16 </filter-mapping>
注意：log4j2不再支持properties文件了，只支持xml，json或是yaml，不指定位置的情况下默认在src/main/resources下查找。
如果需要自定义位置，需要在上面的web.xml中添加以下代码
1 <context-param> 2 <param-name>log4jConfiguration</param-name> 3 <param-value>/WEB-INF/classes/log4j2.xml</param-value> 4 </context-param>
3.log4j2.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2
3 <Configuration status="off" monitorInterval="1800">
4
5 <properties>
6 <property name="LOG_HOME">/opt/logs/hafiz/log4j2Demo/logs</property>
7 <property name="ERROR_LOG_FILE_NAME">error</property>
8 </properties>
9
10
11 <Appenders>
12 <Console name="Console" target="SYSTEM_OUT">
13 <PatternLayout pattern="%d %-5p (%F:%L) - %m%n" />
14 </Console>
15
16 <RollingRandomAccessFile name="ErrorLog"
17 fileName="${LOG_HOME}/${ERROR_LOG_FILE_NAME}.log"
18 filePattern="${LOG_HOME}/${ERROR_LOG_FILE_NAME}.log.%d{yyyy-MM-dd}.gz">
19 <PatternLayout
20 pattern="%d %-5p (%F:%L) - %m%n"/>
21 <Policies>
22 <TimeBasedTriggeringPolicy/>
23 <SizeBasedTriggeringPolicy size="100 MB"/>
24 </Policies>
25 <DefaultRolloverStrategy max="20"/>
26 </RollingRandomAccessFile>
27
28 </Appenders>
29
30 <Loggers>
31 <!-- 3rdparty Loggers -->
32 <logger name="org.springframework.core" level="info">
33 </logger>
34 <logger name="org.springframework.beans" level="info">
35 </logger>
36 <logger name="org.springframework.context" level="info">
37 </logger>
38 <logger name="org.springframework.web" level="info">
39 </logger>
40
41 <logger name="com.hafiz.www.controller" level="error" includeLocation="true" additivity="false">
42 <appender-ref ref="ErrorLog"/>
43 <appender-ref ref="Console"/>
44 </logger>
45
46 <root level="info" includeLocation="true">
47 <appender-ref ref="Console"/>
48 </root>
49 </Loggers>
50 </Configuration>
4.测试类UserController.java
1 package com.hafiz.www.controller;
2
3 import com.hafiz.www.po.UserEntity;
4 import com.hafiz.www.service.UserService;
5 import org.slf4j.Logger;
6 import org.slf4j.LoggerFactory;
7 import org.springframework.beans.factory.annotation.Autowired;
8 import org.springframework.stereotype.Controller;
9 import org.springframework.web.bind.annotation.RequestMapping;
10 import org.springframework.web.bind.annotation.RequestMethod;
11 import org.springframework.web.bind.annotation.ResponseBody;
12
13 import java.util.ArrayList;
14 import java.util.List;
15
16 /**
17 * Desc:用户信息控制器
18 * Created by hafiz.zhang on 2016/8/27.
19 */
20 @Controller
21 @RequestMapping("/user")
22 public class UserController {
23
24 private static final Logger logger = LoggerFactory.getLogger(UserController.class);
25
26 @Autowired
27 private UserService userService;
28
29 @RequestMapping(value = "/all", method = RequestMethod.GET)
30 @ResponseBody
31 public List<UserEntity> getAllUsers(){
32 logger.info("[GET] /user/all getAllUsers");
33 List<UserEntity> list = userService.getAllUsers();
34 logger.debug("This is log of level of debug");
35 logger.trace("log4j2 Demo");
36 logger.error("哎呀，出错啦~");
37 return list;
38 }
39 }
注意：在JVM启动参数中增加 -DLog4jContextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector 开启异步日志.
时间： 2024-10-24 11:26:32