Introduce:
The powerful function of log4j is undeniable, but in practical applications, it is inevitable that a function needs to output a separate log file. How can we separate the required content from the original log and form a separate log file? In fact, this function can be easily achieved with a little configuration on the basis of the existing log4j .
Example:
For the simple configuration of log4j , please refer to the log4j documentation, here is a configuration file:
| # ## Configure the root logger level of log4j to ( DEBUG ) log4j.rootLogger=DEBUG # ## Record the DAO layer log to DAOLog and ALLLog log4j.logger.DAOLOG=DEBUG,DAOLOG,ALLLOG # ## Record the logic layer log to ASLog and ALLLog log4j.logger.ASLOG= DEBUG,ASLOG,ALLLOG # ## Configure ALLLOG - record all log information log4j.appender.ALLLOG = org.apache.log4j.DailyRollingFileAppender log4j.appender.ALLLOG.file=${webapp.root}/logs/ALLLog.log log4j.appender.ALLLOG.DatePattern='.'yyyyMMdd log4j.appender.ALLLOG.layout=org.apache.log4j.PatternLayout log4j.appender.ALLLOG.layout.ConversionPattern=%d{HH\:mm\:ss,SSS} %p %c - %m%n log4j.additivity.ALLLOG=false # ## Configure DAOLOG - record all DAO layer log information log4j.appender.DAOLOG = org.apache.log4j.DailyRollingFileAppender log4j.appender.DAOLOG.file=${webapp.root}/logs/DAOLog.log log4j.appender.DAOLOG.DatePattern='.'yyyyMMdd log4j.appender.DAOLOG.layout=org.apache.log4j.PatternLayout log4j.appender.DAOLOG.layout.ConversionPattern=%d{HH\:mm\:ss,SSS} %p %c - %m%n log4j.additivity.DAOLog=false # ##配置ASLOG-记录所有业务逻辑层层日志信息 log4j.appender.ASLOG=org.apache.log4j.DailyRollingFileAppender log4j.appender.ASLOG.file=${webapp.root}/logs/ASLog.log log4j.appender.ASLOG.DatePattern='.'yyyyMMdd log4j.appender.ASLOG.layout=org.apache.log4j.PatternLayout log4j.appender.ASLOG.layout.ConversionPattern=%d{HH\:mm\:ss,SSS} %p %c - %m%n log4j.additivity.ASLog=false |
说明：
log4j.rootLogger//==配置跟logger日志级别及日志输出位置，如：
log4j.rootLogger=ERROR,file,stdout表示，日志级别为ERROR的日志输出到控制台和file中。
但如果日志要分别输出到不同的文件中，如根据功能模块输出到不同文件，则无需将不同位置在此设置，否则在无法按照功能模块输出日志，导致不同文件记录相同的日志。
log4j.additivity是子Logger是否继承父Logger 的 输出源（appender）的标志位。具体说，默认情况下子Logger会继承父Logger的appender，也就是说子Logger 会在父Logger的appender里输出。若是additivity设为false，则子Logger只会在自己的appender里输出，而不会在父Logger的appender里输出。
转：http://mmz06.blog.163.com/blog/static/12141696201211160321662/