How SpringBoot integrates slf4j and log4j2

Maven dependency

<!--增加log4j2依赖↓-->
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-actuator</artifactId>
  <exclusions>
    <!-- 去除旧log依赖 -->
    <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-web</artifactId>
  <exclusions>
    <!-- 去除旧log依赖 -->
    <exclusion>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-logging</artifactId>
    </exclusion>
  </exclusions>
</dependency>

If other dependencies have log conflicts, you can add the following configuration:

<exclusions>
  <exclusion>
    <groupId>log4j</groupId>
    <artifactId>*</artifactId>
  </exclusion>
  <exclusion>
    <groupId>org.slf4j</groupId>
    <artifactId>*</artifactId>
  </exclusion>
  <exclusion>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>*</artifactId>
  </exclusion>
</exclusions>

log4j2.xml

Place it in resources Directory

<?xml version="1.0" encoding="UTF-8"?>
<!--
  6个优先级从高到低依次为：OFF、FATAL、ERROR、WARN、INFO、DEBUG、TRACE、 ALL。
  如果设置优先级为WARN，那么OFF、FATAL、ERROR、WARN 4个级别的log能正常输出
  设置为OFF 表示不记录log4j2本身的日志，
 -->

<!-- status：用来指定log4j本身的打印日志级别,monitorInterval:指定log4j自动重新配置的监测间隔时间 -->
<configuration status="INFO" monitorInterval="30">
  <!-- 自己设置属性，后面通过${}来访问 -->
<!--  <properties>
    <property name="LOG_HOME">${web:rootDir}/logs</property>
  </properties>-->
  <appenders>
    <!--Appender 1. 输出到Console控制台，指定输出格式和过滤器等级为INFO -->
    <Console name="Console" target="SYSTEM_OUT">
      <!--ThresholdFilter指定日志消息的输出最低层次-->
      <ThresholdFilter level="ALL" onMatch="ACCEPT" onMismatch="DENY"/>
      <PatternLayout pattern="%d{HH:mm:ss.SSS} %-5level %class{36} %L %M - %msg%xEx%n"/>
    </Console>

    <!--Appender 2. 输出到滚动保存的文件, 触发保存日志文件的条件是日志文件大于3KB，只保存最新的10个日志-->
    <File name="allLog" fileName="${LOG_HOME}/all.log">
      <ThresholdFilter level="ALL" onMatch="ACCEPT" onMismatch="DENY"/>
      <PatternLayout charset="UTF-8" pattern="%d{yyyy.MM.dd &#39;at&#39; HH:mm:ss z} %-5level %class{36} %L %M - %msg%xEx%n"/>
    </File>


    <!--Appender 3. 输出到滚动保存的文件, 触发保存日志文件的条件是日志文件大于3KB，只保存最新的10个日志-->
    <RollingFile name="debugLog" fileName="${LOG_HOME}/debug.log" filePattern="${log.path}/debug-%i.log">
      <ThresholdFilter level="DEBUG" onMatch="ACCEPT" onMismatch="DENY"/>
      <PatternLayout charset="UTF-8" pattern="[%-5level][%d{yyyy-MM-dd HH:mm:ss}][%F:%L] - %m%n"/>
      <SizeBasedTriggeringPolicy size="3KB"/>
      <!-- DefaultRolloverStrategy 中的参数max，可以限制 SizeBasedTriggeringPolicy中size超出后，只保留max个存档-->
      <DefaultRolloverStrategy max="10"/>
    </RollingFile>

    <!--Appender 4. 输出到滚动保存的文件, 触发保存日志文件的条件是每分钟第一次的日志事件。ERROR日志是按分钟产生日志 -->
    <RollingFile name="errorLog" fileName="${LOG_HOME}/error.log"
           filePattern="${log.path}/error-%d{yyyy-MM-dd_HH-mm}.log">
      <ThresholdFilter level="ERROR" onMatch="ACCEPT" onMismatch="DENY"/>
      <PatternLayout charset="UTF-8" pattern="[%-5level][%d{yyyy-MM-dd HH:mm:ss}][%C:%F:%L] - %m%n"/>
      <TimeBasedTriggeringPolicy/>
    </RollingFile>

    <RollingFile name="RollingFile" fileName="${LOG_HOME}/rar.log"
           filePattern="${LOG_HOME}/$${date:yyyy-MM}/${FILE_NAME}-%d{MM-dd-yyyy}-%i.log.gz">
      <PatternLayout charset="UTF-8" pattern="%d{yyyy-MM-dd &#39;at&#39; HH:mm:ss z} %-5level %class{36} %L %M - %msg%xEx%n"/>
      <!--日志文件最大值 第二天压缩-->
      <Policies>
        <TimeBasedTriggeringPolicy/>
        <SizeBasedTriggeringPolicy size="10 MB"/>
      </Policies>
    </RollingFile>


  </appenders>
  <!--root 默认加载-->
  <loggers>
    <root level="DEBUG">
      <appender-ref ref="Console"/>
      <!--<appender-ref ref="allLog"/>-->
      <!--<appender-ref ref="debugLog"/>-->
      <!--<appender-ref ref="errorLog"/>-->
      <!--<appender-ref ref="RollingFile"/>-->
    </root>
  </loggers>
</configuration>

LogTest.java

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class LogTest {
  public final Logger logger=LoggerFactory.getLogger(getClass());

  public static void main(String[] args) {
    log.trace("trace");
    log.debug("debug");
    log.warn("warn");
    log.info("info");
    log.error("error");
  }

}

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