Spring Boot误将log4j2.xml识别为Logback配置文件的解决求助

问题背景 #

Spring Boot 2.7.6应用配置log4j2.xml作为日志配置，已排除spring-boot-starter-logging并引入spring-boot-starter-log4j2，但启动时出现两类错误：

1. 初始错误：Spring Boot将log4j2.xml当作Logback配置文件解析，排查后发现liquibase-core引入了logback-classic，排除后仍报错，且dependency:tree已无logback-classic依赖。
2. 后续错误：排除Logback后出现ERROR StatusLogger Unable to create Lookup for ctx，提示缺失org/apache/logging/log4j/util/ServiceLoaderUtil类。

相关配置 #

log4j2.xml #

<?xml version="1.0" encoding="UTF-8"?>
<!-- Extra logging related to initialization of Log4j.
 Set to debug or trace if log4j initialization is failing. -->
<Configuration status="warn">
    <Appenders>
        <!-- Console appender configuration -->
        <Console name="console" target="SYSTEM_OUT">
            <PatternLayout
                    pattern="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n" />
        </Console>
    </Appenders>
    <Loggers>
        <!-- Root logger referring to console appender -->
        <Root level="info" additivity="false">
            <AppenderRef ref="console" />
        </Root>
    </Loggers>
</Configuration>

pom.xml关键依赖 #

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.7.6</version>
</parent>
...
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>
        <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-log4j2</artifactId>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-slf4j-impl</artifactId>
    <version>${log4j-slf4j-impl.version}</version>
    <scope>compile</scope>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>${log4j-core.version}</version>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-layout-template-json</artifactId>
    <version>2.19.0</version>
    <scope>runtime</scope>
</dependency>

错误信息 #

初始错误 #

Logging system failed to initialize using configuration from 'classpath:log4j2.xml'
java.lang.IllegalStateException: Logback configuration error detected: 
ERROR in ch.qos.logback.core.joran.spi.Interpreter@3:17 - no applicable action for [Properties], current ElementPath  is [[Configuration][Properties]]
...

排除Logback后的错误 #

ERROR StatusLogger Unable to create Lookup for ctx
 java.lang.NoClassDefFoundError: org/apache/logging/log4j/util/ServiceLoaderUtil
    at org.apache.logging.log4j.core.impl.ThreadContextDataInjector.getServiceProviders(ThreadContextDataInjector.java:77)

解决方案 #

1. 彻底解决Logback解析log4j2.xml问题 #

• 强制指定日志系统：在application.properties或application.yml中添加配置，明确告诉Spring Boot使用Log4j2：

  spring.main.logging-system=org.springframework.boot.logging.log4j2.Log4J2LoggingSystem
  logging.config=classpath:log4j2.xml
  

• 排查残余Logback依赖：执行命令mvn dependency:tree -Dincludes=ch.qos.logback，检查是否还有其他依赖引入Logback，如有则对应排除。比如liquibase-core的排除配置：

  <dependency>
      <groupId>org.liquibase</groupId>
      <artifactId>liquibase-core</artifactId>
      <exclusions>
          <exclusion>
              <groupId>ch.qos.logback</groupId>
              <artifactId>logback-classic</artifactId>
          </exclusion>
      </exclusions>
  </dependency>
  

2. 解决ServiceLoaderUtil缺失问题 #

• 移除手动指定的Log4j核心依赖：spring-boot-starter-log4j2已经自动管理了log4j-core、log4j-slf4j-impl等依赖的版本，手动指定版本会导致版本不兼容。删除pom中以下依赖：

  <dependency>
      <groupId>org.apache.logging.log4j</groupId>
      <artifactId>log4j-slf4j-impl</artifactId>
      <version>${log4j-slf4j-impl.version}</version>
      <scope>compile</scope>
  </dependency>
  <dependency>
      <groupId>org.apache.logging.log4j</groupId>
      <artifactId>log4j-core</artifactId>
      <version>${log4j-core.version}</version>
  </dependency>
  

• 对齐log4j-layout-template-json版本：Spring Boot 2.7.6对应的Log4j2版本是2.17.1，将log4j-layout-template-json的版本改为2.17.1，或直接使用parent中定义的${log4j2.version}属性：

  <dependency>
      <groupId>org.apache.logging.log4j</groupId>
      <artifactId>log4j-layout-template-json</artifactId>
      <version>${log4j2.version}</version>
      <scope>runtime</scope>
  </dependency>
  

• 更新依赖并清理缓存：执行mvn clean install清理旧依赖并重新构建项目。

内容的提问来源于stack exchange，提问作者gstackoverflow