springmvc返回json或者xml

 <!-- 根据客户端的不同的请求决定不同的view进行响应, 如 /blog/1.json /blog/1.xml -->
    <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
                <!-- 设置为true以忽略对Accept Header的支持-->
                <property name="ignoreAcceptHeader" value="true"/>
                <!-- 在没有扩展名时即: "/user/1" 时的默认展现形式 -->
        <property name="defaultContentType" value="text/html"/>
        
                <!-- 扩展名至mimeType的映射,即 /user.json => application/json -->
        <property name="mediaTypes">
            <map>
                <entry key="json" value="application/json" />
                <entry key="xml" value="application/xml" />
            </map>
        </property>
        <!-- 用于开启 /userinfo/123?format=json 的支持 -->
        <property name="favorParameter" value="false"/>
        <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="/pages"/>
                    <property name="suffix" value=".jsp"></property>
                </bean>
            </list>
        </property>
        <property name="defaultViews">
            <list>
                <!-- for application/json -->
                <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
                <!-- for application/xml -->
                <!-- 
                <bean class="org.springframework.web.servlet.view.xml.MarshallingView" >
                    <property name="marshaller">
                        <bean class="org.springframework.oxm.xstream.XStreamMarshaller"/>
                    </property>
                </bean>
                 -->
            </list>
        </property>
    </bean>