網上的資料眼花繚亂 ， 因為太詳細所以懶得看，下面我就說最簡單的方式，也是專案中常常使用的方式！

1）下載jar包

<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>

2）新建 log4j.xml

src/main/resources/log4j.xml 內容如下：

1. <?xml version="1.0" encoding="UTF-8" ?>
2. <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
3. <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
4. <appender name="console" class="org.apache.log4j.ConsoleAppender">
5. <param name="Target" value="System.out" />
6. <layout class="org.apache.log4j.PatternLayout">
7. <param name="ConversionPattern" value="[CateringLog] %d{yyyy-MM-dd HH:mm:ss,SSS} %-5p %c - %m%n"
   />
8. </layout>
9. </appender>
10. <appender class="org.apache.log4j.RollingFileAppender" name="file">
11. <param name="File" value="d:/companyProject/logs/catering.log" />
12. <param name="Append" value="true" />
13. <param name="MaxFileSize" value="1024KB" />
14. <param name="MaxBackupIndex"
    value="5" />
15. <layout class="org.apache.log4j.PatternLayout">
16. <param name="ConversionPattern" value="[CateringLog] %d{yyyy-MM-dd HH:mm:ss,SSS} %-5p %c - %m%n" />
17. </layout>
18. </appender>
19. <root>
20. <priority value="debug" />
21. <appender-ref ref="console" />
22. <appender-ref ref="file" />
23. </root>
24. <!--通過<logger></logger>的定義可以將各個包中的類日誌輸出到不同的日誌檔案中-->
25. <logger name="org.springframework">
26. <level value="ERROR" />
27. </logger>
28. <logger name="org.mybatis.spring">
29. <level value="ERROR" />
30. </logger>
31. <logger name="net.sf.ehcache">
32. <level value="ERROR" />
33. </logger>
34. <logger name="com.mchange.v2">
35. <level value="ERROR" />
36. </logger>
37. <logger name="java.sql">
38. <level value="debug" />
39. </logger>
40. </log4j:configuration>