首先在pom.xml添加相应的依赖

 <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
            <exclusions>    <!-- 这个很关键  去除默认的日志框架 -->
                <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>

application.properties文件里面加入如下代码

logging.config=classpath:log4j2-spring.xml

resources目录下面新建log4j2-spring.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<!-- status=trace 可以查看log4j的装配过程，相关状态有："trace", "debug", "info", "warn", 
	"error" and "fatal"；monitorInterval检查配置文件是否发生变化，若变化自动刷新配置，单位秒，0关闭此选项。 -->
<configuration status="debug" monitorInterval="30">
    <properties>
        <property name="LogPattern">%date{yyyy-MM-dd HH🇲🇲ss.SSS} %level [%thread][%c][%X] - %msg%n%throwable
        </property>
    </properties>
    <appenders>
        <!-- 定义控制台输出 。follow：当System.setOut或者System.setErr被调用后改变了标准输出后，ConsoleAppender也跟着改变；target输出目标为标准输出还是错误输出：
            "SYSTEM_OUT" or "SYSTEM_ERR" -->
        <Console name="ConsoleAppender" target="SYSTEM_OUT" follow="true">
            <PatternLayout pattern="{LogPattern}"/>
        </Console>
        <File name="FileAppender" fileName="log/my.log" append="true">
            <PatternLayout pattern="{LogPattern}"/>
        </File>
    </appenders>
    <!-- asyncLogger是异步，logger是同步。asyncRoot与root只能选择一个 -->
    <!-- name是logger的名字，若用"."做分隔，代表其父logger；logger的level级别：TRACE, DEBUG, INFO,
        WARN, ERROR, ALL or OFF，若没指定则默认为error；additivity子logger集成父logger的appender，默认值为true -->
    <loggers>
        <!-- Root Logger -->
        <root level="debug" includeLocation="false">
            <appender-ref ref="ConsoleAppender"/>
            <appender-ref ref="FileAppender"/>
        </root>
        <Logger name="Mybatis" level="DEBUG" additivity="true">
        </Logger>
        <Logger name="org.mybatis" level="DEBUG" additivity="true">
        </Logger>
        <Logger name="org.springframework" level="INFO" additivity="true">
        </Logger>
    </loggers>
</configuration>