文件:log4j.properties
log4j.rootLogger=DEBUG, R
log4j.appender.R=org.apache.log4j.FileAppender
log4j.appender.R.file=my.log
log4j.appender.R.Append=true
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%n%n%d%p[%c]-%m%n