系统弄一弄，收获不少。不要maven，不要spring，不要IDEA，就直接弄。

log4j2不再支持properties文件，所以下面会报错，以后只支持XML,JSON,YAML文件格式。
为了快速学习，很多代码糊在一起的，用注释来快速保留。

一，代码

log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration status="WARN">
    <Appenders>
        <!--
        <File name="MyFile" fileName="myLogFile.log" append="false">
            <PatternLayout pattern="%t %-5p %c{2} -  %m%n" />
        </File>
        <Async name="Async">
            <AppenderRef ref="MyFile" />
        </Async>

        <RollingFile name="RollingFile">
            <Filename>mylog.log</Filename>
            <FilePattern>%d{yyyy-MM-dd-hh-mm}.log.zip</FilePattern>
            <PatternLayout>
                <Pattern>%d{yyyy-MM-dd HH:mm:ss a} [%t] %-5level %logger{36} - %msg%n</Pattern>
            </PatternLayout>
            <Policies>
                <TimeBasedTriggeringPolicy interval="1" modulate="true" />
                <SizeBasedTriggeringPolicy size="5KB" />
            </Policies>
            <DefaultRolloverStrategy max="5" />
        </RollingFile>
        -->
        <Console name="consoleAppender" target="SYSTEM_OUT">
            <RegexFilter regex=".*message.*" onMatch="ACCEPT" onMismatch="DENY" />
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss a} [%t] %-5level %logger{36} - %msg%n" />
        </Console>
    </Appenders>
    <Loggers>
        <Root level="debug">
            <!-- <AppenderRef ref="Async" /> -->
            <!-- <AppenderRef ref="RollingFile" /> -->
            <AppenderRef ref="consoleAppender" />
        </Root>
        <!--
        <Root level="trace">
            <AppenderRef ref="consoleAppender" />
        </Root>
        -->
    </Loggers>
</configuration>

Interface3 .java

package com.example.demo;

public interface Interface3 {
    public int warningMessage(int count);
}

Interface4 .java

package com.example.demo;

public interface Interface4 {
    public String errorMessage(String message);
}

DemoApplication.java

package com.example.demo;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.appender.ConsoleAppender;
import org.apache.logging.log4j.core.config.ConfigurationSource;
import org.apache.logging.log4j.core.config.Configurator;
import org.apache.logging.log4j.core.config.builder.api.*;
import org.apache.logging.log4j.core.config.builder.impl.BuiltConfiguration;

import java.io.File;
import java.net.URI;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URISyntaxException;

public class DemoApplication  {


    public static void main(String[] args) throws InterruptedException, FileNotFoundException, IOException, URISyntaxException {
        ConfigurationSource source = new ConfigurationSource(new FileInputStream(new File("D:\\test\\demo\\src\\main\\resources\\log4j2.xml")));
        Configurator.initialize(null, source);
        // log4j2不再支持properties文件，所以下面会报错，以后只支持XML,JSON,YAML文件格式
        // ConfigurationSource source = new ConfigurationSource(new FileInputStream(new File("D:\\test\\demo\\src\\main\\resources\\log4j2.properties")));
        // 配置Log4j
        Configurator.initialize(null, source);
        Logger LOG = LogManager.getLogger(DemoApplication.class);
        /*
        ConfigurationBuilder<BuiltConfiguration> builder = ConfigurationBuilderFactory.newConfigurationBuilder();
        builder.setStatusLevel(Level.WARN);
        builder.setConfigurationName("MyConfig");
        // builder.add(builder.newFilter("ThresholdFilter", Filter.Result.ACCEPT, Filter.Result.NEUTRAL)
        //      .addAttribute("level", Level.DEBUG));
        LayoutComponentBuilder layoutBuilder = builder.newLayout("PatternLayout")
                .addAttribute("pattern", "%d [%t] %-5level: %msg%n");
        ComponentBuilder triggeringPolicy = builder.newComponent("Policies")
                .addComponent(builder.newComponent("SizeBasedTriggeringPolicy")
                        .addAttribute("size", "1KB"));
        // AppenderComponentBuilder appenderComponent = builder.newAppender("Stdout", "CONSOLE").addAttribute("target",
        //      ConsoleAppender.Target.SYSTEM_OUT);
        // appenderComponent.add(
        //      builder.newLayout("PatternLayout")
        //              .addAttribute("pattern", "%d [%t] (%c) %-5level: %msg%n%throwable"));
        AppenderComponentBuilder appenderComponent = builder.newAppender("rolling", "RollingFile")
                        .addAttribute("fileName", "myRollingLogFile.log")
                                .addAttribute("filePattern", "rolling-%d{MM-dd-yy}.log.gz")
                                        .addComponent(layoutBuilder)
                                                .addComponent(triggeringPolicy);
        builder.add(appenderComponent);

        builder.add(builder.newLogger("com.example.demo.myFirstLogger", Level.DEBUG)
                .add(builder.newAppenderRef("Stdout"))
                .addAttribute("additivity", true));
        builder.add(builder.newLogger("com.example.demo.mySecondLogger", Level.WARN)
                .add(builder.newAppenderRef("Stdout"))
                .addAttribute("additivity", true));
        builder.add(builder.newRootLogger(Level.ERROR)
                .add(builder.newAppenderRef("Stdout")));

        LoggerContext ctx = Configurator.initialize(builder.build());
        // Logger LOG = ctx.getRootLogger();
        Logger LOG = ctx.getRootLogger();
        Logger myFirstLogger = ctx.getLogger("com.example.demo.myFirstLogger");
        Logger mySecondLogger = ctx.getLogger("com.example.demo.mySecondLogger");

         */

        LOG.debug("LOG Debug Message");
        LOG.info("LOG Info message");
        LOG.warn("LOG Warn Message");
        LOG.error("LOG error Message");

        Interface3 int3 = (count) -> count + 1;
        Interface4 int4 = (message) -> message + "Parameter Missing";

        LOG.warn("Warning message: Count of files is : " + int3.warningMessage(4));
        LOG.error("Error message: " + int4.errorMessage("Attentions!"));
        /*

        myFirstLogger.info("myFirstLogger Info Message");
        myFirstLogger.error("myFirstLogger Error Message");
        myFirstLogger.fatal("Fatal Message");

        mySecondLogger.warn("mySecondLogger warn Message message");
        mySecondLogger.fatal("mySecondLogger fatal Message message");

        for (int i = 0; i < 100; i++) {
            LOG.info("Info: " + i);
        }

        Object obj = null;
        if (obj == null) LOG.fatal("Object is null!");
        try {
            int a = 5 / 0;
            System.out.println(a);
        } catch (ArithmeticException e) {
            LOG.error("Cannot divide by zero!");
        }
        */
    }
}

二，输出

D:\Java\jdk17\bin\java.exe "-javaagent:D:\JetBrains\IntelliJ IDEA Community Edition 2024.3.1.1\lib\idea_rt.jar=3359:D:\JetBrains\IntelliJ IDEA Community Edition 2024.3.1.1\bin" -Dfile.encoding=UTF-8 -classpath D:\test\demo\target\classes;D:\test\demo\src\lib\log4j-api-2.24.3.jar;D:\test\demo\src\lib\log4j-core-2.24.3.jar com.example.demo.DemoApplication
2025-01-02 13:44:55 下午 [main] INFO  com.example.demo.DemoApplication - LOG Info message
2025-01-02 13:44:55 下午 [main] WARN  com.example.demo.DemoApplication - Warning message: Count of files is : 5
2025-01-02 13:44:55 下午 [main] ERROR com.example.demo.DemoApplication - Error message: Attentions!Parameter Missing

Process finished with exit code 0