Spring mvc 使用 jackson2 返回json格式数据时数据的构成

xml：

<bean id="viewResolver"
          class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="contentNegotiationManager" ref="cnManager"/>
        <property name="viewResolvers"><!-- 针对freemarker的视图配置 --> 
            <list>
                <bean class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver">
                    <property name="viewClass" value="org.springframework.web.servlet.view.freemarker.FreeMarkerView"/>
                   <!-- <property name="viewNames" value=".ftl"/>-->
                    <property name="contentType" value="text/html; charset=utf-8"/>
                    <property name="cache" value="true" />
                    <property name="prefix" value="" />
                    <property name="suffix" value=".ftl" />
                    <property name="order" value="2"/>
                </bean>
                <!--<bean id="liteDeviceDelegatingViewResolver" class="org.springframework.mobile.device.view.LiteDeviceDelegatingViewResolver">-->
                    <!--<constructor-arg>-->
                        <!--<bean-->
                                <!--class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver">-->
                            <!--<property name="cache" value="true"/>-->
                            <!--<property name="requestContextAttribute" value="rc"/>-->
                            <!--<property name="prefix" value=""/>-->
                            <!--<property name="suffix" value=".ftl"/>-->
                            <!--<property name="exposeSpringMacroHelpers" value="true"/>-->
                            <!--<property name="exposeRequestAttributes" value="true"/>-->
                            <!--<property name="exposeSessionAttributes" value="true"/>-->
                            <!--<property name="contentType" value="text/html;charset=UTF-8"/>-->
                        <!--</bean>-->
                    <!--</constructor-arg>-->

                    <!--<property name="mobilePrefix" value="mobile/" />-->
                    <!--<property name="tabletPrefix" value="tablet/" />-->
                    <!--<property name="enableFallback" value="true" />-->
                <!--</bean>-->
                <bean
                        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                    <property name="prefix" value="/WEB-INF/view/jsp/"></property><!-- 配置页面路径 -->
                    <property name="suffix" value=".jsp"></property><!-- 文件以value值结尾 -->
                </bean>
            </list>
        </property>
        <property name="defaultViews">
            <list>
                <bean class="org.springframework.web.servlet.view.json.MappingJackson2JsonView">
                    <!-- <property name="extractValueFromSingleKeyModel" value="true"/> -->
                    <property name="prettyPrint" value="true"/>
                    <property name="contentType" value="text/plain"/>
                </bean>
                <bean class="org.springframework.web.servlet.view.xml.MarshallingView">
                    <constructor-arg ref="jaxb2Marshaller">

                    </constructor-arg>
                </bean>
                <bean class="com.wonders.stpt.bid.controller.JXLExcelView"/>
            </list>
        </property>
    </bean>

    <bean id="jaxb2Marshaller" class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
        <property name="classesToBeBound">
            <list>
                <value>com.wonders.stpt.bid.domain.Route</value>
                <value>com.wonders.stpt.bid.domain.Dictionary</value>
            </list>
        </property>
    </bean><bean id="viewResolver"
          cla