偷懒 log4j配置文件

log4j.properties
log4j.rootLogger=ERROR,stdout
log4j.logger.com.shang=DEBUG           //将com.shang包下的所有类日志纪录级别设置为DEBUG级别
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n