Maven NoClassDefFoundError
🏷️ Maven
使用 Maven 经常会莫名其妙的出现 NoClassDefFoundError，就像下面这种：
java
2018-08-20 11:00:26.230 [main] ERROR o.s.boot.SpringApplication - Application run failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'messageConverters' defined in class path resource [org/springframework/boot/autoconfigure/http/HttpMessageConvertersAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.autoconfigure.http.HttpMessageConverters]: Factory method 'messageConverters' threw exception; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/exc/InvalidDefinitionException
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:590)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1247)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1096)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:535)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:759)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:762)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:398)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:330)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1258)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1246)
at com.xxx.xxx.mqservices.Application.main(Application.java:16)
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.autoconfigure.http.HttpMessageConverters]: Factory method 'messageConverters' threw exception; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/exc/InvalidDefinitionException
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185)
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:582)
... 17 common frames omitted
Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/exc/InvalidDefinitionException
at org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter.<init>(AllEncompassingFormHttpMessageConverter.java:88)
at org.springframework.web.client.RestTemplate.<init>(RestTemplate.java:179)
at org.springframework.boot.autoconfigure.http.HttpMessageConverters.getDefaultConverters(HttpMessageConverters.java:204)
at org.springframework.boot.autoconfigure.http.HttpMessageConverters.<init>(HttpMessageConverters.java:106)
at org.springframework.boot.autoconfigure.http.HttpMessageConverters.<init>(HttpMessageConverters.java:92)
at org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration.messageConverters(HttpMessageConvertersAutoConfiguration.java:72)
at org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration$$EnhancerBySpringCGLIB$$73928262.CGLIB$messageConverters$0(<generated>)
at org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration$$EnhancerBySpringCGLIB$$73928262$$FastClassBySpringCGLIB$$33286c75.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:361)
at org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration$$EnhancerBySpringCGLIB$$73928262.messageConverters(<generated>)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154)
... 18 common frames omitted
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.databind.exc.InvalidDefinitionException
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)
... 34 common frames omitted重点是最后一条消息，可以看出应该是 jackson 相关的包出问题了：
java
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.databind.exc.InvalidDefinitionException这种一般是由于 Maven 依赖的包有冲突导致的。可以使用如下命令来查找是哪里的依赖出了问题。
shell
mvn dependency:tree -Dverbose运行得到如下结果：
java
[INFO] Scanning for projects...
[INFO]
[INFO] -------------------< com.xxx:XxxMqServices >--------------------
[INFO] Building XxxMqServices 1.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
...
[INFO] +- org.elasticsearch:elasticsearch:jar:5.6.10:compile
...
[INFO] | +- com.fasterxml.jackson.core:jackson-core:jar:2.9.6:compile
[INFO] | +- com.fasterxml.jackson.dataformat:jackson-dataformat-smile:jar:2.9.6:compile
[INFO] | +- com.fasterxml.jackson.dataformat:jackson-dataformat-yaml:jar:2.9.6:compile
[INFO] | +- com.fasterxml.jackson.dataformat:jackson-dataformat-cbor:jar:2.9.6:compile
...
[INFO] +- org.codehaus.jackson:jackson-mapper-asl:jar:1.9.2:compile
[INFO] | \- org.codehaus.jackson:jackson-core-asl:jar:1.9.2:compile
...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------可以看到 org.elasticsearch:elasticsearch 包依赖了 com.fasterxml.jackson.core:jackson-core🫙2.9.6 ，而别得地方又同时依赖了 org.codehaus.jackson:jackson-core-asl🫙1.9.2 。
jackson-mapper-asl 最高版本是 1.9.13，而且已经迁移到了 jackson-databind 项目。所以将依赖从
xml
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>1.9.2</version>
</dependency>改成
xml
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.6</version>
</dependency>问题就解决了。