<!-- https://mvnrepository.com/artifact/org.apache.logging.log4j/log4j-core -->
<dependency>
	<groupId>org.apache.logging.log4j</groupId>
	<artifactId>log4j-core</artifactId>
	<version>2.15.0</version><!--$NO-MVN-MAN-VER$-->
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.logging.log4j/log4j-api -->
<dependency>
	<groupId>org.apache.logging.log4j</groupId>
	<artifactId>log4j-api</artifactId>
	<version>2.15.0</version><!--$NO-MVN-MAN-VER$-->
</dependency>
log4j2的配置文件
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <!--全局参数-->
    <Properties>
        <Property name="pattern">%d{yyyy-MM-dd HH:mm:ss,SSS} %5p %c{1}:%L - %m%n</Property>
        <Property name="logDir">/data/logs/dust-server</Property>
    </Properties>
    <Loggers>
        <Root level="INFO">
            <AppenderRef ref="console"/>
            <AppenderRef ref="rolling_file"/>
        </Root>
    </Loggers>
    <Appenders>
        <!-- 定义输出到控制台 -->
        <Console name="console" target="SYSTEM_OUT" follow="true">
            <!--控制台只输出level及以上级别的信息-->
            <ThresholdFilter level="INFO" onMatch="ACCEPT" onMismatch="DENY"/>
            <PatternLayout>
                <Pattern>${pattern}</Pattern>
            </PatternLayout>
        </Console>
        <!-- 同一来源的Appender可以定义多个RollingFile，定义按天存储日志 -->
        <RollingFile name="rolling_file"
                     fileName="${logDir}/dust-server.log"
                     filePattern="${logDir}/dust-server_%d{yyyy-MM-dd}.log">
            <ThresholdFilter level="INFO" onMatch="ACCEPT" onMismatch="DENY"/>
            <PatternLayout>
                <Pattern>${pattern}</Pattern>
            </PatternLayout>
            <Policies>
                <TimeBasedTriggeringPolicy interval="1"/>
            </Policies>
            <!-- 日志保留策略，配置只保留七天 -->
            <DefaultRolloverStrategy>
                <Delete basePath="${logDir}/" maxDepth="1">
                    <IfFileName glob="dust-server_*.log" />
                    <IfLastModified age="7d" />
                </Delete>
            </DefaultRolloverStrategy>
        </RollingFile>
    </Appenders>
</Configuration>
编写一个测试类
public class Log4j2Demo {
    private static  final Logger LOGGER=LogManager.getLogger();
    public static void main(String[] args) {
        String username="${java:os}";
        LOGGER.info("Hello, {}",username);
log4j2快速修复的措施
临时解决方案
设置jvm参数 “-Dlog4j2.formatMsgNoLookups=true”
设置“log4j2.formatMsgNoLookups=True”
系统环境变量“FORMAT_MESSAGES_PATTERN_DISABLE_LOOKUPS”设置为“true”
关闭对应应用的网络外连，禁止主动外连
举一个设置环境变量的方法
# vi /etc/proflie
// 在最后追加
# export FORMAT_MESSAGES_PATTERN_DISABLE_LOOKUPS=true
// 保存退出
#  esc + wq
// 让环境变量立即生效需要执行如下命令
# source /etc/proflie
// 一般需要重新注销系统才能生效，最后可以通过echo命令测试一下：  
# echo $PATH
https://blog.csdn.net/lumingzhu111/article/details/121871114

https://jingyan.baidu.com/article/b87fe19e6b408852183568e8.html