轻松搞懂 Log4j2 配置

	<!--log4j2jar-->
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
        <version>2.12.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.12.1</version>
    </dependency>
    <!--log4j2的slf4j实现-->
     <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-slf4j-impl</artifactId>
        <version>2.12.1</version>
    </dependency>

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
  <Appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
  </Appenders>
  <Loggers>
    <Root level="error">
      <AppenderRef ref="Console"/>
    </Root>
  </Loggers>
</Configuration>

<?xml version="1.0" encoding="UTF-8"?>;
<Configuration>
  <Properties>
    <Property name="name1">value</property>
    <Property name="name2" value="value2"/>
  </Properties>
  <Filter type="type" ... />
  <Appenders>
    <Appender type="type" name="name">
      <Filter type="type" ... />
    </Appender>
    ...
  </Appenders>
  <Loggers>
    <Logger name="name1">
      <Filter type="type" ... />
    </Logger>
    ...
    <Root level="level">
      <AppenderRef ref="name"/>
    </Root>
  </Loggers>
</Configuration>

    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %l - %m%n" />
        </Console>
        <RollingRandomAccessFile name="RollingRandomAccessFile" fileName="${LOG_HOME}/${FILE_NAME}"
                     filePattern="${LOG_HOME}/$${date:yyyy-MM}/${FILE_NAME}-%d{yyyy-MM-dd HH-mm}-%i.log">
            <PatternLayout pattern="%d %p %c{1.} [%t] - %m%n"/>
            <Policies>
                <TimeBasedTriggeringPolicy />
                <SizeBasedTriggeringPolicy size="20 MB"/>
            </Policies>
            <DefaultRolloverStrategy max="10"/>
        </RollingRandomAccessFile>
    </Appenders>

    <Loggers>
        <Root level="all">
            <AppenderRef ref="Console" />
            <AppenderRef ref="RollingRandomAccessFile" />
        </Root>
        <Logger name="com.marchsoft.controller.UserController" level="info" additivity="false">
            <AppenderRef ref="Console" />
            <AppenderRef ref="RollingRandomAccessFile" />
        </Logger>
    </Loggers>

	<!-- 定义 -->
    <properties>
        <property name="LOG_HOME">D:/logs</property>
        <property name="FILE_NAME">mylog.txt</property>
    </properties>

	<!--使用, 在fileName属性中引用-->
	<RollingRandomAccessFile name="RollingRandomAccessFile" fileName="${LOG_HOME}/${FILE_NAME}".../>

<dependency>
     <groupId>org.apache.logging.log4j</groupId>
     <artifactId>log4j-slf4j-impl</artifactId>
     <version>2.12.1</version>
</dependency>

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class Slf4jDemo {
    public static void main(String[] args) {
        Logger logger = LoggerFactory.getLogger(Slf4jDemo.class);

        logger.info("Slf4j log info");
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<!--根配置标签-->
<!--Configuration标签至少要指定status标签, status指定的为缺省日志显示等级-->
<Configuration status="WARN">
    <!--自定义属性通过${}来引用, 用自定已属性时为了方便同意管理-->
    <properties>
        <property name="LOG_HOME">D:/logs</property>
        <property name="FILE_NAME">mylog.txt</property>
    </properties>

    <!--日志输出端, 可以时Console, File, RollingFile, RollingRandomAccessFile等等-->
    <!--Rolling开头的输出端具有文本分割功能,可以按照时间(TimeBasedTriggeringPolicy)或者文件大小(SizeBasedTriggeringPolicy)进行分割-->
    <!--RollingRandomAccessFileRollingRandomAccessFile 与 RollingFile 在功能上基本一致，但是底层的实现有所区别，RollingFileAppender 底层是 BufferedOutputStream，
    RollingRandomAccessFileAppender 底层是使用 ByteBuffer + RandomAccessFile ，性能上有了很大的提升。-->
    <Appenders>
        <!--此处name为Console指定一个名称(可任意), target指定输出源名称(非任意)-->
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %l - %m%n" />
        </Console>
        <!--name指定名称, fileName日志文件路径名称, filePattern分割日志路径名称, pattern日志内容的格式-->
        <!--该Appender每天建一个日志分割文件夹,当mylog.txt文件达到20M,会将的内容转移到分割文件,此时mylog.txt中不会有之前的2M内容-->
        <RollingRandomAccessFile name="RollingRandomAccessFile" fileName="${LOG_HOME}/${FILE_NAME}"
                     filePattern="${LOG_HOME}/$${date:yyyy-MM}/${FILE_NAME}-%d{yyyy-MM-dd HH-mm}-%i.log">
            <PatternLayout pattern="%d %p %c{1.} [%t] - %m%n"/>
            <Policies>
                <!--interval日志颗粒度, 与filePattern有关联, 时间HH-mm颗粒度为分中, 时间HH颗粒度为消息, 时间yyy-MM-dd为天-->
<!--                <TimeBasedTriggeringPolicy interval="1"/>-->
                <!--size文件大小, 达到时对日志进行分割, 单位有MB、KB-->
                <SizeBasedTriggeringPolicy size="20 MB"/>
            </Policies>
            <!--最大分割数量-->
            <DefaultRolloverStrategy max="10"/>
        </RollingRandomAccessFile>
    </Appenders>
    <!--日志器,产生日志-->
    <Loggers>
        <!--level日志输出级别-->
        <Root level="all">
            <!--指定该日志器输出的Appender, 此处对对控制台和文件进行输出-->
            <AppenderRef ref="Console" />
            <AppenderRef ref="RollingRandomAccessFile" />
        </Root>

        <Logger name="com.marchsoft.controller.UserController" level="all" additivity="false">
            <AppenderRef ref="Console" />
            <AppenderRef ref="RollingRandomAccessFile" />
        </Logger>
    </Loggers>
</Configuration>