Spring集成JSON报错：java.lang.ClassNotFoundException: org.codehaus.jackson.JsonProcessingException

先看异常信息：

SEVERE: StandardWrapper.Throwable
java.lang.NoClassDefFoundError: org/codehaus/jackson/JsonProcessingException
	at java.lang.Class.getDeclaredConstructors0(Native Method)
	at java.lang.Class.privateGetDeclaredConstructors(Class.java:2493)
	at java.lang.Class.getDeclaredConstructors(Class.java:1901)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.determineCandidateConstructors(AutowiredAnnotationBeanPostProcessor.java:234)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineConstructorsFromBeanPostProcessors(AbstractAutowireCapableBeanFactory.java:1040)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1013)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:700)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
	at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:658)
	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:624)
	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:672)
	at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:543)
	at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:484)
	at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
	at javax.servlet.GenericServlet.init(GenericServlet.java:158)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1231)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1144)
	at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1031)
	at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4909)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5196)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1069)
	at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1719)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:744)
Caused by: java.lang.ClassNotFoundException: org.codehaus.jackson.JsonProcessingException
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1305)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1157)
	... 38 more

看我们的pom.xml配置：

		
		4.0.2.RELEASE
		
		3.2.6
		
		1.7.7
		1.2.17
		2.8.1
	

	
		
			junit
			junit
			4.11
			
			test
		
		
		
			org.springframework
			spring-core
			${spring.version}
		

		
			org.springframework
			spring-web
			${spring.version}
		
		
			org.springframework
			spring-oxm
			${spring.version}
		
		
			org.springframework
			spring-tx
			${spring.version}
		

		
			org.springframework
			spring-jdbc
			${spring.version}
		

		
			org.springframework
			spring-webmvc
			${spring.version}
		
		
			org.springframework
			spring-aop
			${spring.version}
		

		
			org.springframework
			spring-context-support
			${spring.version}
		

		
			org.springframework
			spring-test
			${spring.version}
		
		
		
			org.mybatis
			mybatis
			${mybatis.version}
		
		
		
			org.mybatis
			mybatis-spring
			1.2.2
		
		
		
			javax
			javaee-api
			7.0
		
		
		
			mysql
			mysql-connector-java
			5.1.30
		
		
		
			commons-dbcp
			commons-dbcp
			1.2.2
		
		
		
			jstl
			jstl
			1.2
		
		
		
		
			log4j
			log4j
			${log4j.version}
		


		
		
			com.alibaba
			fastjson
			1.1.41
		

		
			org.slf4j
			slf4j-api
			${slf4j.version}
		

		
			org.slf4j
			slf4j-log4j12
			${slf4j.version}
		
		
		
		
			com.fasterxml.jackson.core
			jackson-databind
			${jackson.version}
		
		
			com.fasterxml.jackson.core
			jackson-annotations
			${jackson.version}
		
		
			com.fasterxml.jackson.core
			jackson-core
			${jackson.version}
		
		
		
			commons-fileupload
			commons-fileupload
			1.3.1
		
		
			commons-io
			commons-io
			2.4
		
		
			commons-codec
			commons-codec
			1.9
		
		
			org.apache.httpcomponents
			httpclient
			4.5.2
		

	

可以看到红色的jackson已经被配置进去了，为什么还报错？

经过排查发现Spring的配置是从网上拷贝的，版本比较老，其中关于json的配置是：

   
      
          
              
                text/html;charset=UTF-8  
              
          
      

如果将Spring的版本提高到最新的版本(4.3.2.RELEASE)，这里其实是会报错的。

原来是实现类变化了，现在更改为：

        class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">  
          
              
                text/html;charset=UTF-8  
              
          
     

注意中间的  2 。