为何Log4j无法找到配置文件？IntelliJ IDEA报无Appender警告

问题现象 #

运行代码时控制台抛出以下警告：

log4j:WARN No appenders could be found for logger (org.gerosd.Manager).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See ... for more info.

相关代码与配置 #

Manager.java #

package org.gerosd;

import org.apache.log4j.PropertyConfigurator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Manager {
    private static final Logger logger = LoggerFactory.getLogger(Manager.class);

    public static void main(String[] args) {
        PropertyConfigurator.configure("D:/work/projects/Log4j/src/main/resources/log4j2.xml");
        logger.info("Hello World");
    }
}

log4j2.xml #

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <Appenders>
        <Console name="LogToConsole" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
        </Console>
        <RollingFile name="LogToRollingFile" fileName="logs/app.log"
                     filePattern="logs/$${date:yyyy-MM}/app-%d{MM-dd-yyyy}-%i.log.gz">
            <PatternLayout>
                <Pattern>%d %p %c{1.} [%t] %m%n</Pattern>
            </PatternLayout>
            <Policies>
                <TimeBasedTriggeringPolicy />
                <SizeBasedTriggeringPolicy size="10 MB"/>
            </Policies>
        </RollingFile>

    </Appenders>
    <Loggers>
        <!-- avoid duplicated logs with additivity=false -->
         <Logger name="org.gerosd.Manager" level="warn" additivity="false">
            <AppenderRef ref="LogToRollingFile"/>
        </Logger>
        <Root level="warn">
            <AppenderRef ref="LogToConsole"/>
        </Root>
    </Loggers>
</Configuration>

build.gradle #

plugins {
    id 'java'
}

group = 'org.gerosd'
version = '1.0-SNAPSHOT'

repositories {
    mavenCentral()
}

dependencies {
    implementation 'org.apache.logging.log4j:log4j-core:2.20.0'
    implementation 'org.apache.logging.log4j:log4j-api:2.20.0'
    implementation 'org.slf4j:slf4j-api:2.0.9'
    implementation 'org.slf4j:slf4j-reload4j:2.0.9'
}

已尝试操作 #

添加了org.apache.logging.log4j:log4j-slf4j2-impl:2.20.0依赖，但配置文件仍未被读取，控制台不再输出错误信息。

解决方案 #

问题根源在于依赖冲突+错误的初始化方式，按以下步骤修复：

1. 调整依赖，移除冲突的桥接包 #

项目同时引入了slf4j-reload4j（适配Log4j 1.x）和Log4j 2核心包，导致SLF4J绑定到旧的Log4j 1.x实现，无法识别Log4j 2格式的配置。

修改build.gradle的依赖部分，移除slf4j-reload4j，保留log4j-slf4j2-impl作为SLF4J到Log4j 2的桥接：

dependencies {
    implementation 'org.apache.logging.log4j:log4j-core:2.20.0'
    implementation 'org.apache.logging.log4j:log4j-api:2.20.0'
    implementation 'org.slf4j:slf4j-api:2.0.9'
    // 移除slf4j-reload4j，改用Log4j2的SLF4J桥接
    implementation 'org.apache.logging.log4j:log4j-slf4j2-impl:2.20.0'
}

2. 替换错误的初始化代码 #

PropertyConfigurator是Log4j 1.x的初始化类，Log4j 2完全不兼容该API。且配置文件放在src/main/resources下时，Log4j 2会自动扫描加载该目录下的log4j2.xml，无需手动指定路径。

修改Manager.java，删除手动初始化代码：

package org.gerosd;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Manager {
    private static final Logger logger = LoggerFactory.getLogger(Manager.class);

    public static void main(String[] args) {
        // 移除PropertyConfigurator相关代码，Log4j2会自动加载配置
        logger.info("Hello World");
    }
}

3. 调整日志级别（可选） #

配置中org.gerosd.Manager的日志级别为warn，而代码调用的是logger.info()，这条日志不会输出。若需看到info级别的日志，修改log4j2.xml中对应Logger的级别：

<Logger name="org.gerosd.Manager" level="info" additivity="false">
    <AppenderRef ref="LogToRollingFile"/>
</Logger>

4. 验证配置 #

重新构建项目并运行，此时Log4j 2会自动读取src/main/resources/log4j2.xml，警告信息消失，日志将按照配置输出到控制台和滚动文件中。

内容的提问来源于stack exchange，提问作者gerosd