这个问题害了我弄了几天才弄好，后来开了http://www.tuicool.com/articles/FJnmAvY

这篇文章才算把问题解决了。

首先将spring的bean文件头文件改一下

改成

<?xml version="1.0" encoding="UTF-8"?>

<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:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"

xmlns:mvc="http://www.springframework.org/schema/mvc"

xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

http://www.springframework.org/schema/context

http://www.springframework.org/schema/context/spring-context-3.0.xsd

http://www.springframework.org/schema/aop

http://www.springframework.org/schema/aop/spring-aop-3.0.xsd

http://www.springframework.org/schema/tx

http://www.springframework.org/schema/tx/spring-tx-3.0.xsd

http://www.springframework.org/schema/mvc

http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">

也就是把以前spring-mvc-3.0.xsd 升级到  spring-mvc-3.2.xsd，如果已经是 spring-mvc-3.2.xsd的就不用改了

然后把<mvc:annotation-driven>修改成如下格式

<mvc:annotation-driven content-negotiation-manager="contentNegotiationManager" />

<bean id="contentNegotiationManager" class="org.springframework.web.accept.ContentNegotiationManagerFactoryBean">

<property name="favorPathExtension" value="false" />

<property name="favorParameter" value="false" />

<property name="ignoreAcceptHeader" value="false" />

<property name="mediaTypes" >

<value>

atom=application/atom+xml

html=text/html

json=application/json

*=*/*

</value>

</property>

</bean>

jackson的包就引用

jackson-core-2.5.2.jar

jackson-annotations-2.5.2.jar

jackson-databind-2.5.2.jar

这三个包就可以了