log4j:WARN Please initialize the log4j system properly

eclipse运行程序时候出现下面错误：
log4j:WARN No appenders could be found for logger (org.apache.hadoop.security.Gr
oups).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more in
fo.

**

解决办法：

新建log4j.properties文件，放到src目录下面
内容：

log4j.rootLogger=debug, stdout, R 

log4j.appender.stdout=org.apache.log4j.ConsoleAppender 
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout 

#log4j.appender.stdout.layout.ConversionPattern=%5p - %m%n 
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n

log4j.appender.R=org.apache.log4j.RollingFileAppender 
log4j.appender.R.File=log4j.log 

log4j.appender.R.MaxFileSize=100KB 
log4j.appender.R.MaxBackupIndex=1 

log4j.appender.R.layout=org.apache.log4j.PatternLayout 
#log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n 
log4j.appender.R.layout.ConversionPattern=%d %p [%c] - %m%n

log4j.logger.com.codefutures=DEBUG 

完成！重新运行即可出现打印的log信息