Log4j&Log4j2 框架知识点总结

淡淡的烟草味﹌ 2023-02-17 15:00 17阅读 0赞

### 前言 ###

最近重新看了下Log4j & Log4j2. 将知识点总结记录.

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### 正文 ###

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##### Log4j 知识要点 #####

*  Log4j 4大组件
    
     *  Logger - 日志输出
     *  Appender - 附着器
     *  Layout - 布局
 *  Appender 种类
    
     *  Console 控制台输出
     *  File 文件输出
     *  RollingFile 文件输出(滚动文件输出)
     *  注意: File文件输出和RollingFile文件输出的区别？(RollingFile带滚动机制？)
 *  Layout 种类
    
     *  PatternLayout
     *  HTMLLayout
     *  SimpleLayout
 *  PatternLayout
    
     *  %d : (date)日期. (%d \{hh:MM:ss. SSSS\})
     *  %c: (class)所在类
     *  %t: (thread)所在线程.
     *  %l: (location)所在位置. (类-线程-代码行数 Testlog4.main(TestLog4.java:10))
     *  %m%n： 换行符.
     *  %p: (priority)优先级.
 *  日志优先级类型
    
     *  DEBUG: 调试级别.
     *  INFO: 消息级别.
     *  WARN: 警告级别.
     *  ERROR: 错误级别.
     *  FATAL: 严重错误级别.
     *  OFF: 停止级别.
     *  ALL: 所有优先级.
     *  TRACE: 跟踪级别(比Debug级别更低)

注: 前4种为常用优先级别. 后面几种优先级不是特别常用.

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##### Log4j2 知识要点 #####

Log4j2配置文件一般为xml或者jsn. 以xml配置文件为例子.

*  `<Configuration>`标签
 *  `<Appenders>`标签
    
     *  `<Console>`标签
     *  `<File>`标签 `<File name="FileLog" fileName="log/test.log" append="false">`
     *  `<RollingFile>`标签
        
         *  `<PatternLayout>`标签`<PatternLayout pattern="[%d{HH:mm:ss.SSSS}[%p] - %L %m%n]/"/>`
         *  `<ThresholdFilter>`标签 `<ThresholdFilter level="info" onMatch="ACCEPT" onMismatch="DENY"/>`
         *  `<Policies>`策略标签
            
             *  `<TimeBasedTriggeringPolicy/>`
             *  `<SizeBasedTriggeringPolicy Size="100MB"/>`
 *  `<Loggers>`标签
    
     *  `<Logger>`标签 `<logger name="org.springframework" level="INFO">`
     *  `<Appender-ref>`标签 `<Appender-ref ref="Console"/><Appender-ref ref="RollingFile"/>`

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### 相关实战 ###

##### Log4j #####

*  Maven导入相关包 log4j-1.2.17.jar

*  配置文件 & 默认配置文件 log4j.properties

### root logger
    log4j.rootLogger = WARN, Console, R
    #first commit
    #log4j.rootLogger = DEBUG, Console, R
    
    
    ### console appender
    log4j.appender.Console=org.apache.log4j.ConsoleAppender
    log4j.appender.Console.layout=org.apache.log4j.PatternLayout
    log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] [%L] - %m %n
    
    ### file appender
    log4j.appender.R=org.apache.log4j.RollingFileAppender
    log4j.appender.R.File=helloworld.log
    log4j.appender.R.MaxFileSize=50MB
    log4j.appender.R.MaxBackupIndex=30
    log4j.appender.R.layout=org.apache.log4j.PatternLayout
    log4j.appender.R.layout.ConversionPattern=%d [%t] %-5p [%c] [%L] -%m %n 
    
    ### details
    log4j.appender.com.yanxml.arsenal.java=INFO
    log4j.appender.com.yanxml.arsenal.java.log4j.simple=WARN

*  public static final Logger logger = Logger.getLogger(Test.class)
 *  输出 logger.info(“”); / logger.debug(“debug”):
 *  结果

2020-06-14 21:24:07,298 [main] WARN  [com.yanxml.arsenal.java.log4j.simple.SimpleLog4jDemo] [12] - [WARN] INFO  
    2020-06-14 21:24:07,304 [main] ERROR [com.yanxml.arsenal.java.log4j.simple.SimpleLog4jDemo] [13] - [ERROR] INFO  
    2020-06-14 21:24:07,304 [main] FATAL [com.yanxml.arsenal.java.log4j.simple.SimpleLog4jDemo] [14] - [FATAL] INFO

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##### Log4j-SpringBoot #####

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##### Log4j2 #####

*  Maven导入相关包
 *  配置文件 log4j2.xml ( )

<?xml version="1.0" encoding="UTF-8"?>
    <configuration status="WARN"  monitorInterval="30">
    	<appenders>
    		<console name="Console" target="SYSTEM_OUT">
    			<PatternLayout pattern="[%d{HH:mm:ss.SSSS}][%p]-%l-%m%n"/>
    		</console>
    		
    		
    		<File name="FileLog" fileName="log/test.log" append="false">
    			<PatternLayout pattern="%d{HH:mm:ss.SSSS} %-5level %class{36} %L %M -%msg%xEx%n" />
    		</File>
    		
    		<RollingFile name="RollingFile" filename="${sys:user.home}/logs/rollingfile.log"
    			filePattern="${sys:user.home}/logs/$${date:yyyy-MM}/rolling-%d{yyyy-MM-dd}-%i.log">
    			<ThresholdFilter level="info" onMatch="ACCEPT" onMismatch="DENY"/>
    			<PatternLayout pattern="[%d{HH:mm:ss.SSSS}[%p] - %L %m%n]/"/>
    			<Policies>
    				<TimeBasedTriggeringPolicy />
    				<SizeBasedTriggeringPolicy Size="100MB"/>
    			</Policies>
    		</RollingFile>		
    	</appenders>
    	
    	<loggers>
    		<logger name="org.springframework" level="INFO">
    			<Appender-ref ref="Console"/>
    			<Appender-ref ref="RollingFile"/>
    		</logger>
    		<logger name="org.mybatis" level="INFO"/>
    		
    		<root level="INFO">
    			<appender-ref ref="Console"/>
    			<appender-ref ref="RollingFile"/>
    		</root>
    	</loggers>
    </configuration>

*  public static final Logger logger = LoggerManager.getLogger(Test.class)
 *  输出 logger.info(“”); / logger.debug(“debug”):
 *  输出结果

//[11:43:16.0509][TRACE]-com.yanxml.arsenal.java.log4j2.simple.Log4j2Demo.main(Log4j2Demo.java:10)-TRACE
    //[11:43:16.0510][DEBUG]-com.yanxml.arsenal.java.log4j2.simple.Log4j2Demo.main(Log4j2Demo.java:11)-DEBUG
    //[11:43:16.0511][INFO]-com.yanxml.arsenal.java.log4j2.simple.Log4j2Demo.main(Log4j2Demo.java:12)-INFO
    //[11:43:16.0511][WARN]-com.yanxml.arsenal.java.log4j2.simple.Log4j2Demo.main(Log4j2Demo.java:13)-WARN
    //[11:43:16.0511][ERROR]-com.yanxml.arsenal.java.log4j2.simple.Log4j2Demo.main(Log4j2Demo.java:14)-ERROR
    //[11:43:16.0512][FATAL]-com.yanxml.arsenal.java.log4j2.simple.Log4j2Demo.main(Log4j2Demo.java:15)-FATAL

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### 其余实战内容 ###

其余Log4j实战作用

*  Info Warn Error 分别记录在不同的日志文件内(`Log4j2的<thresholdFilter>标签 加3个<RollingFileAppender>`实现.)
 *  敏感字符串替换
 *  文件按照时间 / 大小创建新的文件 & 分割
    
     *  `Log4j2`的`<TimeBasedTriggeringPolicy>`和`Log4j2`的`<SizeBasedTriggeringPolicy>`
     *  `Log4j`的`Log4j.appender.R.MaxFileSize`

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### Others 个人总结 ###

*  [Log4j总结][Log4j]
 *  [Log4j基础教程][Log4j 1]
 *  [Log4j2配置详解][Log4j2]
 *  [Log4j2 Demos 实战内容][Log4j2 Demos]

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### Others-官方文件 ###

*  [log4j2.x][]

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### Others-优秀好文 ###

*  [最详细的Log4j总结][Log4j 2]
 *  Java日志终极指南
 *  混乱的 Java 日志体系
 *  为什么要使用SLF4J而不是Log4J
 *  聊一聊log4j2配置文件log4j2.xml

[Log4j]: https://blog.csdn.net/u010416101/article/details/81275281
[Log4j 1]: https://blog.csdn.net/u010416101/article/details/81275689
[Log4j2]: https://blog.csdn.net/u010416101/article/details/81278293
[Log4j2 Demos]: https://blog.csdn.net/u010416101/article/details/81278360
[log4j2.x]: https://logging.apache.org/log4j/2.x/
[Log4j 2]: http://www.codeceo.com/article/log4j-usage.html