关于Log4j不重启重新加载配置文件

系统可能出现某些问题，我们就需要将相关的日志打印出来，就需要修改日志级别。一般情况下，都需要重启程序，但是有时候在线上要求不能重启服务，就需要动态加载配置文件。第一种方式：利用Log4j的定时扫描功能。Log4j会自动扫描配置文件，默认1分钟。

public void log4jConfigAndWatch(){
String configFilename = JFWebConfig.class.getClassLoader().getResource("").getPath() + "log4j.properties";
PropertyConfigurator.configureAndWatch(configFilename);
}

#log4j.rootLogger=error,stdout,info,debug,error
log4j.rootCategory=ERROR,stdout,info,debug,error
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n

log4j.logger.info=info
log4j.appender.info=org.apache.log4j.DailyRollingFileAppender
log4j.appender.info.layout=org.apache.log4j.PatternLayout
log4j.appender.info.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n
log4j.appender.info.datePattern='.'yyyy-MM-dd'.log'
log4j.appender.info.Threshold = INFO
log4j.appender.info.append=true
log4j.appender.info.File=${catalina.base}/logs/info

log4j.logger.debug=debug
log4j.appender.debug=org.apache.log4j.DailyRollingFileAppender
log4j.appender.debug.layout=org.apache.log4j.PatternLayout
log4j.appender.debug.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n
log4j.appender.debug.datePattern='.'yyyy-MM-dd'.log'
log4j.appender.debug.Threshold = DEBUG
log4j.appender.debug.append=true
log4j.appender.debug.File=${catalina.base}/logs/debug

log4j.logger.error=error
log4j.appender.error=org.apache.log4j.DailyRollingFileAppender
log4j.appender.error.layout=org.apache.log4j.PatternLayout
log4j.appender.error.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n
log4j.appender.error.datePattern='.'yyyy-MM-dd'.log'
log4j.appender.error.Threshold = ERROR
log4j.appender.error.append=true
log4j.appender.error.File=${catalina.base}/logs/error

第二种方式：利用jvm的属性，动态加载。启动的时候添加环境属性-Dlog4j.level=error通过修改JVM的系统属性即可。或者tomcat的catalina.bat[windows]/catalina.sh[linux]添加jvm属性JAVA_OPTS="-server -Xms256m -Xmx1024m -Dlog4j.level=error"[linux]set JAVA_OPTS= -DMYFLAG=2 [windows]

#log4j.rootLogger=error,stdout,info,debug,error
log4j.rootCategory=${log4j.level},stdout,info,debug,error
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n

log4j.logger.info=info
log4j.appender.info=org.apache.log4j.DailyRollingFileAppender
log4j.appender.info.layout=org.apache.log4j.PatternLayout
log4j.appender.info.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n
log4j.appender.info.datePattern='.'yyyy-MM-dd'.log'
log4j.appender.info.Threshold = INFO
log4j.appender.info.append=true
log4j.appender.info.File=${catalina.base}/logs/info

log4j.logger.debug=debug
log4j.appender.debug=org.apache.log4j.DailyRollingFileAppender
log4j.appender.debug.layout=org.apache.log4j.PatternLayout
log4j.appender.debug.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n
log4j.appender.debug.datePattern='.'yyyy-MM-dd'.log'
log4j.appender.debug.Threshold = DEBUG
log4j.appender.debug.append=true
log4j.appender.debug.File=${catalina.base}/logs/debug

log4j.logger.error=error
log4j.appender.error=org.apache.log4j.DailyRollingFileAppender
log4j.appender.error.layout=org.apache.log4j.PatternLayout
log4j.appender.error.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n
log4j.appender.error.datePattern='.'yyyy-MM-dd'.log'
log4j.appender.error.Threshold = ERROR
log4j.appender.error.append=true
log4j.appender.error.File=${catalina.base}/logs/error

System.setProperty("log4j.level", 你的level);String configFilename = ToolsController.class.getClassLoader().getResource("").getPath() + "log4j.properties";PropertyConfigurator.configure(configFilename);