SpringBoot使用Log4j2出现异常：Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons

淡淡的烟草味﹌ 2022-05-23 04:05 22阅读 0赞

# 异常信息 #

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory
        at org.springframework.boot.SpringApplication.<clinit>(SpringApplication.java:179)
        at com.example.log4j2.Log4j2Application.main(Log4j2Application.java:10)
    Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory
        at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        ... 2 more

## pom.xml中的依赖配置 ##

<dependencies>
            <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>
                <version>2.0.0.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>

通过依赖配置可以看出，**使用的是log4j2的2.0.0.RELEASE版本**，springboot是1.5.14.BUILD-SNAPSHOT，出错的地方就在这里，出现版本后依赖jar包没有正常引入，在启动时SpringApplication中的Logger使用报错，缺少了jar包依赖，具体代码为：

private static final Log logger = LogFactory.getLog(SpringApplication.class);

# 解决方法 #

将log4j2的版本信息去掉，就可正常启动

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-log4j2</artifactId>
    </dependency>

![这里写图片描述][20180601160030404]

[20180601160030404]: /images/20220523/543c046160624ebe8b59fd7915b440a7.png