1.需要的jar如下:

!-- log4j -->
 <dependency>
     <groupId>log4j</groupId>
     <artifactId>log4j</artifactId>
     <version>1.2.17</version>
 </dependency>
 <dependency>
     <groupId>org.slf4j</groupId>
     <artifactId>slf4j-api</artifactId>
     <version>1.7.4</version>
 </dependency>
 <dependency>    
     <groupId>org.slf4j</groupId>    
     <artifactId>slf4j-log4j12</artifactId>    
     <version>1.7.4</version>    
     <scope>runtime</scope>    
 </dependency> 

2.将log4j.properties放入项目src路径下即可，虚拟机会自动加载日志配置文件，文件内容如下：

 ### set log levels ###
 log4j.rootLogger = DEBUG , C , D , E 

 ### console ###
 log4j.appender.C = org.apache.log4j.ConsoleAppender
 log4j.appender.C.Target = System.out
 log4j.appender.C.layout = org.apache.log4j.PatternLayout
 log4j.appender.C.layout.ConversionPattern = [mybatis_study][%p] [%-d{yyyy-MM-dd HH\:mm\:ss}] %C.%M(%L) | %m%n

 ### log file ###
 log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
 log4j.appender.D.File = ../logs/mybatis_study.log
 log4j.appender.D.Append = true
 log4j.appender.D.Threshold = INFO 
 log4j.appender.D.layout = org.apache.log4j.PatternLayout
 log4j.appender.D.layout.ConversionPattern = [mybatis_study][%p] [%-d{yyyy-MM-dd HH\:mm\:ss}] %C.%M(%L) | %m%n

 ### exception ###
 log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
 log4j.appender.E.File = ../logs/mybatis_study_error.log 
 log4j.appender.E.Append = true
 log4j.appender.E.Threshold = ERROR 
 log4j.appender.E.layout = org.apache.log4j.PatternLayout
 log4j.appender.E.layout.ConversionPattern = [mybatis_study][%p] [%-d{yyyy-MM-dd HH\:mm\:ss}] %C.%M(%L) | %m%n

 ###mybatis show sql###
 log4j.logger.com.ibatis=debug
 log4j.logger.com.ibatis.common.jdbc.SimpleDataSource=debug
 log4j.logger.com.ibatis.common.jdbc.ScriptRunner=debug
 log4j.logger.com.ibatis.sqlmap.engine.impl.SqlMapClientDelegate=debug

 log4j.logger.java.sql.Connection=debug
 log4j.logger.java.sql.Statement=debug
 log4j.logger.java.sql.PreparedStatement=debug

3.也可以配置log4j.xml,如下：

 <?xml version="1.0" encoding="UTF-8"?>    
     <!DOCTYPE log4j:configuration PUBLIC "-//APACHE//DTD LOG4J 1.2//EN" "log4j.dtd">  
     <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">  

       <!-- [控制台STDOUT] -->  
       <appender name="console" class="org.apache.log4j.ConsoleAppender">  
          <param name="encoding" value="GBK" />  
          <param name="target" value="System.out" />  
          <layout class="org.apache.log4j.PatternLayout">  
            <param name="ConversionPattern" value="%-5p %c{2} - %m%n" />  
          </layout>  
       </appender>  

       <!-- [公共Appender] -->  
       <appender name="DEFAULT-APPENDER" class="org.apache.log4j.DailyRollingFileAppender">  
          <param name="File" value="${webapp.root}/logs/rms-default.log" />  
          <param name="Append" value="true" />  
          <param name="encoding" value="GBK" />  
          <param name="DatePattern" value="‘.‘yyyy-MM-dd‘.log‘" />  
          <layout class="org.apache.log4j.PatternLayout">  
         <param name="ConversionPattern" value="%d %-5p %c{2} - %m%n" />  
          </layout>  
        </appender>  

        <!-- [错误日志APPENDER] -->  
        <appender name="ERROR-APPENDER" class="org.apache.log4j.DailyRollingFileAppender">  
          <param name="File" value="${webapp.root}/logs/rms-error.log" />  
          <param name="Append" value="true" />  
          <param name="encoding" value="GBK" />  
          <param name="threshold" value="error" />  
          <param name="DatePattern" value="‘.‘yyyy-MM-dd‘.log‘" />  
          <layout class="org.apache.log4j.PatternLayout">  
             <param name="ConversionPattern" value="%d %-5p %c{2} - %m%n" />  
          </layout>  
        </appender>  

        <!-- Root Logger -->  
        <root>  
            <level value="${rootLevel}"></level>  
            <appender-ref ref="DEFAULT-APPENDER" />  
            <appender-ref ref="ERROR-APPENDER" />  
            <appender-ref ref="console" />  
        </root>  
     </log4j:configuration>