去掉内置的logback

 <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>

加入log4j2

  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-log4j2</artifactId>
  </dependency>

加入 log4j2.xml

只用RollingRandomAccessFile ，其它基本不用

<Configuration status="WARN" monitorInterval="300">  
    <properties>  
        <property name="LOG_HOME">/logs</property>  
        <property name="FILE_NAME">log</property>  
    </properties>  
    <Appenders>  
        <Console name="Console" target="SYSTEM_OUT">  
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} [%t] %-5p - %m %l%n" />  
        </Console>  
        <RollingRandomAccessFile name="RollingFile"  
            fileName="${LOG_HOME}/${FILE_NAME}.log"  
            filePattern="${LOG_HOME}/${FILE_NAME}-%d{yyyy-MM-dd}-%i.log">  
            <PatternLayout  
                pattern="%d{yyyy-MM-dd HH:mm:ss} [%t] %-5p - %m %l%n" />  
            <Policies>  
                <TimeBasedTriggeringPolicy interval="1" />  
                <SizeBasedTriggeringPolicy size="20 MB" />  
            </Policies>  
            <DefaultRolloverStrategy max="20" />  
        </RollingRandomAccessFile>  
    </Appenders>  
  
    <Loggers>  
         <!-- 全局level 设为 info -->
        <Root level="info">  
            <AppenderRef ref="Console" />  
            <AppenderRef ref="RollingFile" />  
        </Root>  
        <!-- 自己项目的 level 设为debug  -->
        <Logger name="com.myapp" level="trace" additivity="false">  
            <AppenderRef ref="RollingFile" />  
            <AppenderRef ref="Console" />  
        </Logger>  
       
    </Loggers>  
</Configuration> 

springboot自动会扫描class目录下的配置， 扫到就会启用。