log4j.rootLogger=info,stdout,R  
log4j.appender.stdout=org.apache.log4j.ConsoleAppender  
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout  
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%c:%L) %d{yyyy-MM-dd HH:mm:ss,SSS} ---- %m%n  
  
log4j.appender.R=org.apache.log4j.RollingFileAppender  
log4j.appender.R.File=${catalina.home}/logs/download.log
log4j.appender.R.MaxFileSize=1GB  
log4j.appender.R.MaxBackupIndex=3   
log4j.appender.R.layout=org.apache.log4j.PatternLayout  
log4j.appender.R.layout.ConversionPattern=%5p [%t] (%c:%L) %d{yyyy-MM-dd HH:mm:ss,SSS} ---- %m%n  

log4j.appender.R.MaxFileSize=1GB   文件大小
log4j.appender.R.MaxBackupIndex=3  文件个数

当超过大小限制，就会自动生成文件