spring mvc 返回json配置出错

Question

spring版本3.2.8
maven中jackson的配置

<!--json begin-->
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-core-lgpl</artifactId>
            <version>1.8.1</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-lgpl</artifactId>
            <version>1.8.1</version>
        </dependency>
        <!--json end-->

classpath下有JsonProcessingException，如下图

spring的配置如下：

<mvc:annotation-driven />
    <context:component-scan base-package="com.zuobiao.zhang.controller" />

    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping" />
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
        <property name="messageConverters">
            <list>
                <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                    <property name="supportedMediaTypes">
                        <list>
                            <value>text/html;charset=UTF-8</value>
                            <value>application/json;charset=UTF-8</value>
                        </list>
                    </property>
                </bean>
            </list>
        </property>
    </bean>

    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="contentType" value="text/html"/>
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

一运行还是报错，错误信息如下：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter#1' defined in class path resource [spring/spring-dispatch.xml]: Initialization of bean failed; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:529)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:296)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:293)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:628)
    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: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:4923)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5215)
    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.manageApp(HostConfig.java:1678)
    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:497)
    at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
    at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
    at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:463)
    at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:413)
    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:497)
    at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
    at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
    at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1471)
    at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76)
    at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1312)
    at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1404)
    at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:832)
    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:497)
    at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:323)
    at sun.rmi.transport.Transport$1.run(Transport.java:200)
    at sun.rmi.transport.Transport$1.run(Transport.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
    at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:568)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:826)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$256(TCPTransport.java:683)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:682)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getDeclaredConstructors(Class.java:2020)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.determineCandidateConstructors(AutowiredAnnotationBeanPostProcessor.java:231)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineConstructorsFromBeanPostProcessors(AbstractAutowireCapableBeanFactory.java:1002)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:975)
    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.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:269)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:121)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveManagedList(BeanDefinitionValueResolver.java:350)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:154)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1417)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1158)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
    ... 63 more
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.core.JsonProcessingException
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1333)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1167)
    ... 78 more

我试着切换成这样的jackson包，配置如下：

<dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.4.6</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.4.6</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.4.6</version>
        </dependency>

结果还是同样的问题！

吐槽：这种问题真不知道是什么情况，查了一上午的，编程序查错误的时间真实太浪费了！

Answer 1

java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException

你引入的jar包错了

Answer 2

<dependency>
    <groupId>org.codehaus.jackson</groupId>
    <artifactId>jackson-core-lgpl</artifactId>
    <version>1.8.1</version>
</dependency>

你引的这个lgpl协议的jackson-core包里面JsonProcessingException的package是 org.codehaus.jackson，不是com.fasterxml.jackson.core。

你maven应该引 com.fasterxml.jackson 的