1.导入jar包

<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>slf4j-api</artifactId>
  <version>1.7.2</version>
</dependency>
<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>slf4j-log4j12</artifactId>
  <version>1.7.5</version>
</dependency>
<dependency>
  <groupId>log4j</groupId>
  <artifactId>log4j</artifactId>
  <version>1.2.17</version>
</dependency>

　　2.生成配置文件 src\main\resources\log4j.propertes

log4j.rootLogger=info,ROLLING_FILE  
log4j.appender.ROLLING_FILE = org.apache.log4j.ConsoleAppender  
log4j.appender.ROLLING_FILE.encoding=utf-8  (* utf-8后面不能有空格，utf为小写)
log4j.appender.ROLLING_FILE.File = stock.log  
log4j.appender.ROLLING_FILE.Append = true  
log4j.appender.ROLLING_FILE.MaxFileSize= 20MB  
log4j.appender.ROLLING_FILE.MaxBackupIndex= 2
log4j.appender.ROLLING_FILE.layout = org.apache.log4j.PatternLayout  
log4j.appender.ROLLING_FILE.layout.ConversionPattern=[log] %d - %c - %-4r [%t] %-5p %c %x - %m%n 

补充：文件格式为utf-8 （idea右下角显示）

　　File ->settings... -> File Encoding ->IDE Encoding (UTF-8) Project Encoding (UTF-8)

　　File -> other settings -> default Encoding ->  File Encoding ->IDE Encoding (UTF-8) Project Encoding (UTF-8)

　　3.在类中使用

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

private Logger logger = LoggerFactory.getLogger(xxx.class);
logger.info("write log message")
logger.info(e.getMessage());

slf4j的使用