1.添加log4j相关依赖

在pom.xml文件中添加相关依赖：

<!--配置log4j-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-log4j2</artifactId>
        </dependency>
        <!-- 加上这个才能辨认到log4j2.yml文件 -->
        <dependency>
            <groupId>com.fasterxml.jackson.dataformat</groupId>
            <artifactId>jackson-dataformat-yaml</artifactId>
            <version>2.9.3</version>
        </dependency>

2.去除其他log依赖

应该去除掉其他依赖中包含的log依赖，否则会有冲突。去除依赖的代码如下：

<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>
        
         <!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
            <exclusions>
                <exclusion>
                    <!--配置log4j-->
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

3.添加日志配置文件

在resource文件夹下添加log4j2.yml文件，文件内容如下：

Configuration:
  status: warn

  Properties: # 定义全局变量
    Property: # 缺省配置（用于开发环境）。其他环境需要在VM参数中指定，如下：
      #测试：-Dlog.level.console=warn -Dlog.level.xjj=trace
      #生产：-Dlog.level.console=warn -Dlog.level.xjj=info
      - name: log.level.console
        value: trace
      - name: log.level.xjj
        value: trace
      - name: log.path
        value: logs
      - name: project.name
        value: my-spring-boot

  Appenders:
    Console:  #输出到控制台
      name: CONSOLE
      target: SYSTEM_OUT
      ThresholdFilter:
        level: ${sys:log.level.console} # “sys:”表示：如果VM参数中没指定这个变量值，则使用本文件中定义的缺省全局变量值
        onMatch: ACCEPT
        onMismatch: DENY
      PatternLayout:
        pattern: "%d{yyyy-MM-dd HH:mm:ss,SSS}:%4p %t (%F:%L) - %m%n"

    RollingFile: # 输出到文件，超过128MB归档
      - name: ROLLING_FILE
        ignoreExceptions: false
        fileName: ${log.path}/${project.name}.log
        filePattern: "${log.path}/$${date:yyyy-MM}/${project.name}-%d{yyyy-MM-dd}-%i.log.gz"
        PatternLayout:
          pattern: "%d{yyyy-MM-dd HH:mm:ss,SSS}:%4p %t (%F:%L) - %m%n"
        Policies:
          SizeBasedTriggeringPolicy:
            size: "128 MB"
        DefaultRolloverStrategy:
          max: 1000

      - name: EXCEPTION
        ignoreExceptions: false
        fileName: ${log.path}/exception.log
        filePattern: "${log.path}/$${date:yyyy-MM}/${project.name}-%d{yyyy-MM-dd}-%i.log.gz"
        PatternLayout:
          pattern: "%d{yyyy-MM-dd HH:mm:ss,SSS}:%4p %t (%F:%L) - %m%n"
        Policies:
          SizeBasedTriggeringPolicy:
            size: "128 MB"
        DefaultRolloverStrategy:
          max: 1000

      - name: WEB_REQUEST
        ignoreExceptions: false
        fileName: ${log.path}/web_request.log
        filePattern: "${log.path}/$${date:yyyy-MM}/${project.name}-%d{yyyy-MM-dd}-%i.log.gz"
        PatternLayout:
          pattern: "%d{yyyy-MM-dd HH:mm:ss,SSS}:%4p %t (%F:%L) - %m%n"
        Policies:
          SizeBasedTriggeringPolicy:
            size: "128 MB"
        DefaultRolloverStrategy:
          max: 1000

      - name: MYBATIS_SQL
        ignoreExceptions: false
        fileName: ${log.path}/mybatis_sql.log
        filePattern: "${log.path}/$${date:yyyy-MM}/${project.name}-%d{yyyy-MM-dd}-%i.log.gz"
        PatternLayout:
          pattern: "%d{yyyy-MM-dd HH:mm:ss,SSS}:%4p %t (%F:%L) - %m%n"
        Policies:
          SizeBasedTriggeringPolicy:
            size: "128 MB"
        DefaultRolloverStrategy:
          max: 1000

      - name: TIME_TASK
        ignoreExceptions: false
        fileName: ${log.path}/time_task.log
        filePattern: "${log.path}/$${date:yyyy-MM}/${project.name}-%d{yyyy-MM-dd}-%i.log.gz"
        PatternLayout:
          pattern: "%d{yyyy-MM-dd HH:mm:ss,SSS}:%4p %t (%F:%L) - %m%n"
        Policies:
          SizeBasedTriggeringPolicy:
            size: "128 MB"
        DefaultRolloverStrategy:
          max: 1000

      - name: ASYNC_TASK
        ignoreExceptions: false
        fileName: ${log.path}/async_task.log
        filePattern: "${log.path}/$${date:yyyy-MM}/${project.name}-%d{yyyy-MM-dd}-%i.log.gz"
        PatternLayout:
          pattern: "%d{yyyy-MM-dd HH:mm:ss,SSS}:%4p %t (%F:%L) - %m%n"
        Policies:
          SizeBasedTriggeringPolicy:
            size: "128 MB"
        DefaultRolloverStrategy:
          max: 1000


  Loggers:
    Root:
      level: info
      AppenderRef:
        - ref: CONSOLE
        - ref: ROLLING_FILE
    Logger:
      - name: WEB_REQUEST_LOG
        additivity: false
        level: info
        AppenderRef:
            - ref: WEB_REQUEST

      - name: com.example.demo.business #打印sql执行日志
        additivity: false
        level: trace
        AppenderRef:
          - ref: MYBATIS_SQL

      - name: TIME_TASK_LOG
        additivity: false
        level: trace
        AppenderRef:
          - ref: TIME_TASK

      - name: ASYNC_TASK_LOG
        additivity: false
        level: trace
        AppenderRef:
          - ref: ASYNC_TASK

      - name: EXCEPTION_LOG
        additivity: false
        level: trace
        AppenderRef:
          - ref: EXCEPTION

需要注意在配置文件中Logger:标签下添加多个日志项目。其中

 - name: com.example.demo.business #打印sql执行日志
        additivity: false
        level: trace
        AppenderRef:
          - ref: MYBATIS_SQL

配置为打印mybatis执行的sql语句。

4.重启项目

重启项目，日志配置即可成功。