一、起因 

    从spring 3.1.0升级到spring 3.2.0时，配置文件servlet.xml中出错。 

错误信息： 

java.lang.String cannot be cast to org.springframework.http.MediaType

错误原因：是spring3.2开始不推荐使用setMediaTypes等直接设置这些数据， 而是通过ContentNegotiationManager（ContentNegotiationManagerFactoryBean），所以采用map标签的方式直接转换会出现异常信息。 

二、ContentNegotiatingViewResolver 解释 

引用

三、配置实例 

1. spring 3.1.0 

<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="ignoreAcceptHeader" value="true"/>
        <property name="defaultContentType" value="text/html"/>
        <property name="mediaTypes">
            <map>
                <entry key="json" value="application/json" />
                <entry key="xml" value="application/xml" />
            </map>
        </property>
        <property name="viewResolvers">
            <list>
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
                <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                    <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
                    <property name="prefix" value="/WEB-INF/pages/"/>
                    <property name="suffix" value=".jsp"></property>
                </bean>
            </list>
        </property>
        <property name="defaultViews">
            <list>
                <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
                <bean class="org.springframework.web.servlet.view.xml.MarshallingView" >
                    <property name="marshaller">
                        <bean class="org.springframework.oxm.xstream.XStreamMarshaller"/>
                    </property>
                </bean>
            </list>
        </property>
    </bean>

2. spring 3.1.0/3.2.0 

<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="ignoreAcceptHeader" value="true"/>
        <property name="defaultContentType" value="text/html"/>
        <property name="mediaTypes">
            <value>
                json=application/json,
                xml=application/xml
            </value>
        </property>
        <property name="viewResolvers">
            <list>
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
                <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                    <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
                    <property name="prefix" value="/WEB-INF/pages/"/>
                    <property name="suffix" value=".jsp"></property>
                </bean>
            </list>
        </property>
        <property name="defaultViews">
            <list>
                <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
                <bean class="org.springframework.web.servlet.view.xml.MarshallingView" >
                    <property name="marshaller">
                        <bean class="org.springframework.oxm.xstream.XStreamMarshaller"/>
                    </property>
                </bean>
            </list>
        </property>
    </bean>

3. spring 3.2.0 

<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="ignoreAcceptHeader" value="true"/>
        <property name="defaultContentType" value="text/html"/>
        <property name="contentNegotiationManager">
            <bean class="org.springframework.web.accept.ContentNegotiationManagerFactoryBean">
                <property name="ignoreAcceptHeader" value="true"/>
                <property name="defaultContentType" value="text/html"/>
                <property name="mediaTypes">
                    <map>
                        <entry key="json" value="application/json" />
                        <entry key="xml" value="application/xml" />
                    </map>
                </property>
            </bean>
        </property>
        <property name="viewResolvers">
            <list>
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
                <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                    <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
                    <property name="prefix" value="/WEB-INF/pages/"/>
                    <property name="suffix" value=".jsp"></property>
                </bean>
            </list>
        </property>
        <property name="defaultViews">
            <list>
                <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
                <bean class="org.springframework.web.servlet.view.xml.MarshallingView" >
                    <property name="marshaller">
                        <bean class="org.springframework.oxm.xstream.XStreamMarshaller"/>
                    </property>
                </bean>
            </list>
        </property>
    </bean>

4. spring 3.2.x (推荐) 

               <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">                  <property name="ignoreAcceptHeader" value="true"/>                  <property name="defaultContentType" value="text/html"/>                  <property name="contentNegotiationManager">                      <bean class="org.springframework.web.accept.ContentNegotiationManagerFactoryBean">                          <property name="ignoreAcceptHeader" value="true"/>                          <property name="defaultContentType" value="text/html"/>                          <property name="mediaTypes">                              <props>                                  <prop key="json">application/json</prop>                                  <prop key="xml">application/xml</prop>                              </props>                          </property>                      </bean>                  </property>                  <property name="viewResolvers">                      <list>                          <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />                          <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">                              <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>                              <property name="prefix" value="/WEB-INF/pages/"/>                              <property name="suffix" value=".jsp"></property>                          </bean>                      </list>                  </property>                  <property name="defaultViews">                      <list>                          <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />                          <bean class="org.springframework.web.servlet.view.xml.MarshallingView" >                              <property name="marshaller">                                  <bean class="org.springframework.oxm.xstream.XStreamMarshaller"/>                              </property>                          </bean>                      </list>                  </property>              </bean>
<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="ignoreAcceptHeader" value="true"/>
        <property name="defaultContentType" value="text/html"/>
        <property name="contentNegotiationManager">
            <bean class="org.springframework.web.accept.ContentNegotiationManagerFactoryBean">
                <property name="ignoreAcceptHeader" value="true"/>
                <property name="defaultContentType" value="text/html"/>
                <property name="mediaTypes">
                    <props>
                        <prop key="json">application/json</prop>
                        <prop key="xml">application/xml</prop>
                    </props>
                </property>
            </bean>
        </property>
        <property name="viewResolvers">
            <list>
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
                <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                    <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
                    <property name="prefix" value="/WEB-INF/pages/"/>
                    <property name="suffix" value=".jsp"></property>
                </bean>
            </list>
        </property>
        <property name="defaultViews">
            <list>
                <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
                <bean class="org.springframework.web.servlet.view.xml.MarshallingView" >
                    <property name="marshaller">
                        <bean class="org.springframework.oxm.xstream.XStreamMarshaller"/>
                    </property>
                </bean>
            </list>
        </property>
    </bean>