log4j 介紹
1.通過log4j可以看到程序運行過程中更詳細的信息
(1)經常使用log4j查看日誌
2.使用
(1)導入log4j的jar包
(2)複製log4j配置文件到src下(log4j.properties文件)
log4j.rootLogger=info, stdout, R
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=example.log
log4j.appender.R.MaxFileSize=100KB
# Keep one backup file
log4j.appender.R.MaxBackupIndex=5
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n
3.設置日誌級別
log4j.rootLogger=info,stdout
(1)info:看到基本信息
(2)debug:看到更詳細信息