调试json格式输出，出现以下错误：
HTTP Status 500 - Servlet.init() for servlet HelloDispatcher threw exception
type Exception report
message Servlet.init() for servlet HelloDispatcher threw exception
description The server encountered an internal error that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: Servlet.init() for servlet HelloDispatcher threw exception org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:784) org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:802) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1410) org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Thread.java:745)
root cause
org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 75 in XML document from class path resource [mvc.xml] is invalid; nested exception is org.xml.sax.SAXParseException; lineNumber: 75; columnNumber: 30; cvc-complex-type.2.4.c: 通配符的匹配很全面, 但无法找到元素 'mvc:annotation-driven' 的声明。 org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:399) org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:336) org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304) org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:181) org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:217) org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:188) org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:129) org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:613) org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:514) org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:668) org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:634) org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:682) org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:553) org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:494) org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:138) javax.servlet.GenericServlet.init(GenericServlet.java:158) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:784) org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:802) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1410) org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Thread.java:745)
root cause
org.xml.sax.SAXParseException; lineNumber: 75; columnNumber: 30; cvc-complex-type.2.4.c: 通配符的匹配很全面, 但无法找到元素 'mvc:annotation-driven' 的声明。 com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:203) com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(ErrorHandlerWrapper.java:134) com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:396) com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:327) com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:284) com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator$XSIErrorReporter.reportError(XMLSchemaValidator.java:452) com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.reportSchemaError(XMLSchemaValidator.java:3230) com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.handleStartElement(XMLSchemaValidator.java:1911) com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.emptyElement(XMLSchemaValidator.java:760) com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(XMLNSDocumentScannerImpl.java:351) com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2784) com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:602) com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:112) com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:505) com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:841) com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:770) com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141) com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:243) com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339) org.springframework.beans.factory.xml.DefaultDocumentLoader.loadDocument(DefaultDocumentLoader.java:76) org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadDocument(XmlBeanDefinitionReader.java:429) org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:391) org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:336) org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304) org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:181) org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:217) org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:188) org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:129) org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:613) org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:514) org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:668) org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:634) org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:682) org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:553) org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:494) org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:138) javax.servlet.GenericServlet.init(GenericServlet.java:158) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:784) org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:802) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1410) org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Thread.java:745)
其实这个错误是用于配置文件引起的，mvc.xml配置的beans的命名空间有误，原来是这样的：
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/tool" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tool http://www.springframework.org/schema/tool/spring-tool.xsd">
其实，应该这样配置：
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
同时，应该加入以下配置：
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
<property name="messageConverters">
<list>
<bean id="stringConverter" class="org.springframework.http.converter.StringHttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>text/html;charset=UTF-8value>
<value>application/json;charset=UTF-8value>
<value>text/plain;charset=UTF-8value>
list>
property>
bean>
<bean id="jsonConverter" class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>text/html;charset=UTF-8value>
<value>application/json;charset=UTF-8value>
<value>text/plain;charset=UTF-8value>
list>
property>
bean>
list>
property>
bean>
<mvc:annotation-driven />
这里的变化是：
- 添加
- 其次使用org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter适配器，而不是原先的org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter适配器，大概是从SpringMvc3.1开始改变的