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在SpringMVC中使用Jackson实现json输出时配置如下：

<!-- 输出对象转JSON支持   -->
<bean id="stringConverter" class="org.springframework.http.converter.StringHttpMessageConverter">   <property name="supportedMediaTypes">    <list>     <value>text/plain;charset=UTF-8</value>    </list>   </property>  </bean>  <bean id="jsonConverter"   class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"></bean>    <bean   class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">   <property name="messageConverters">    <list>     <ref bean="stringConverter"/>     <ref bean="jsonConverter" />    </list>   </property>  </bean>

Maven 坐标情况如下：

<dependency>   <groupId>org.apache.geronimo.specs</groupId>   <artifactId>geronimo-servlet_2.5_spec</artifactId>   <version>1.2</version>  </dependency>  <dependency>   <groupId>org.springframework</groupId>   <artifactId>spring-web</artifactId>   <version>3.2.10.RELEASE</version>  </dependency>  <dependency>   <groupId>org.springframework</groupId>   <artifactId>spring-webmvc</artifactId>   <version>3.2.10.RELEASE</version>  </dependency>  <dependency>  <groupId>com.fasterxml.jackson.jaxrs</groupId>  <artifactId>jackson-jaxrs-xml-provider</artifactId>  <version>2.4.1</version>  </dependency>

出现异常如下：

严重: Servlet /pcrm threw load() exception java.lang.ClassNotFoundException: org.codehaus.jackson.JsonProcessingException  at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1718)  at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1569)  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:231)  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineConstructorsFromBeanPostProcessors(AbstractAutowireCapableBeanFactory.java:1003)  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:976)  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:487)  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)  at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:293)  at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)  at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)  at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:191)  at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:633)  at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)  at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)  at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651)  at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:602)  at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665)  at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:521)  at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:462)  at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)  at javax.servlet.GenericServlet.init(GenericServlet.java:158)  at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1279)  at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1192)  at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087)  at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5210)  at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5493)  at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)  at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)  at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)  at java.util.concurrent.FutureTask.run(FutureTask.java:262)  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)  at java.lang.Thread.run(Thread.java:744)

一开始以为没有导入Jackson的Jar包，但排查后发现Maven坐标有了，Jar包也导入项目了，但还是一直错。于是我在导入的Jackson包中查找 org.codehaus.jackson.JsonProcessingException类，发现导入的Jackson包中，并不是org.codehaus的Jackson包，而是com.fasterxml的Jackson包。所以确定是Maven坐标导错了。

解决方案：

<dependency>   <groupId>com.fasterxml.jackson.jaxrs</groupId>   <artifactId>jackson-jaxrs-xml-provider</artifactId>   <version>2.4.1</version>  </dependency>

改成

<dependency> <groupId>org.codehaus.jackson</groupId> <artifactId>jackson-mapper-asl</artifactId> <version>1.9.4</version> </dependency>