使用slf4j写日志

Maven加两个依赖

http://mvnrepository.com/artifact/org.slf4j/slf4j-api

http://mvnrepository.com/artifact/org.slf4j/slf4j-log4j12

src/main/resources/ 放入 log4j.properties

内容如下：

log4j.rootLogger=INFO,stdout,R

log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout 
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} [%t] [%c] [%p] - %m%n

log4j.appender.R=org.apache.log4j.RollingFileAppender 
log4j.appender.R.File=spider-job3.log 
log4j.appender.R.MaxFileSize=500KB 
log4j.appender.R.MaxBackupIndex=1 
log4j.appender.R.layout=org.apache.log4j.PatternLayout 
log4j.appender.R.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} [%t] [%c] [%p] - %m%n 

log4j.rootLogger=INFO,stdout,R
生产中一般用info或者error，测试用debug
可以设置级别： debug>info>error

Logger logger = LoggerFactory.getLogger(getClass());

logger.error("现在时间是{}",System.currentTimeMillis());