1.在springBootStudio项目中添加Module。

2.选择Spring Initializr，点击next。

3.Group填写com.chanchifeng，Artifact填写log4j。

4.点击next。

5.Content_root和Module file location选择springBootStudio项目路径。

6.修改pom.xml的添加log4j2，核心代码如下：

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<dependencies>

	<dependency>
	    <groupId>org.springframework.boot</groupId>
	    <artifactId>spring-boot-starter-web</artifactId>
	</dependency>
	
	<dependency>
	    <groupId>org.springframework.boot</groupId>
	    <artifactId>spring-boot-starter-test</artifactId>
	    <scope>test</scope>
	</dependency>
	
	<!-- log4j -->
	<dependency>
	    <groupId>org.springframework.boot</groupId>
	    <artifactId>spring-boot-starter</artifactId>
	    <exclusions>
	        <exclusion>
	            <groupId>org.springframework.boot</groupId>
	            <artifactId>spring-boot-starter-logging</artifactId>
	        </exclusion>
	    </exclusions>
	</dependency>
	
	<dependency>
	    <groupId>org.springframework.boot</groupId>
	    <artifactId>spring-boot-starter-log4j2</artifactId>
	</dependency>

</dependencies>

7.修改application.properties，核心代码如下：

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###log4j配置
logging.config=classpath:log4j2.xml

8.在resources下添加log4j2.xml，代码如下：

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<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <!-- 设置日志输出的格式 -->
            <PatternLayout pattern="[%d{HH:mm:ss:SSS}] [%p] - %l - %m%n"/>
        </Console>
        <RollingFile name="RollingFileInfo" fileName="D:/info.log"
                     filePattern="D:/$${date:yyyy-MM}/info-%d{yyyy-MM-dd}-%i.log">
            <Filters>
                <ThresholdFilter level="INFO"/>
            </Filters>
            <PatternLayout pattern="[%d{HH:mm:ss:SSS}] [%p] - %l - %m%n"/>
            <Policies>
                <TimeBasedTriggeringPolicy/>
                <SizeBasedTriggeringPolicy size="100 MB"/>
            </Policies>
        </RollingFile>
    </appenders>

    <loggers>
        <root level="info">
            <appender-ref ref="Console"/>
            <appender-ref ref="RollingFileInfo"/>
        </root>
    </loggers>

</Configuration>

9.编写测试类Log4jApplicationTests，并查看日志文件是否正常输出，代码如下：

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private static Logger logger = LoggerFactory.getLogger(PageController.class);

@Test
public void contextLoads() {
    logger.info("hello log4j.");
}

10.查看日志，如下图：