MappingJacksonJsonView返回顶级json对象 [英] MappingJacksonJsonView return top-level json object

问题描述

我转换为控制器以使用ContentNegotiatingViewResolver而不是MessageConverters来支持多种输出类型。使用json，我使用MappingJacksonJsonView：

I converted to controller to use ContentNegotiatingViewResolver instead of MessageConverters to support multiple output types. With json, I am using MappingJacksonJsonView:

<bean
    class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
    <property name="order" value="1" />
    <property name="mediaTypes">
        <map>
            <entry key="html" value="text/html"/>
            <entry key="json" value="application/json" />
            <entry key="xml" value="application/xml" />
        </map>
    </property>
    <property name="defaultViews">
        <list>
            <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
            <bean class="org.springframework.web.servlet.view.xml.MarshallingView">
                <constructor-arg>
                    <bean class="org.springframework.oxm.xstream.XStreamMarshaller" />
                </constructor-arg>
            </bean>                         
        </list>
    </property>
    <property name="ignoreAcceptHeader" value="true" />
    <property name="defaultContentType" value="application/json" />
</bean>

使用以下控制器逻辑：

@RequestMapping(value = "/id/{id}", method = RequestMethod.GET)
public ModelAndView getById(@PathVariable (value="id") String id) {
    MyObject ret = doGetById(id);
    ModelAndView modelAndView = new ModelAndView("common/single");
    modelAndView.addObject("myObject", ret);
    return modelAndView;
}

当我访问/id/1234.json时，json返回如下：

The json return when I access /id/1234.json is something like:

{
   myObject: {
        field1:"abc",
        field2:"efg"
   }
}

我有办法将myObject设置为相反的顶级节点，所以它看起来像这样：

Is there a way for my to set myObject as the top level node for the result so it look like this instead:

{
    field1:"abc",
    field2:"efg"
}

推荐答案

正在发生的事情是Spring MVC正在使用ModelAndView并将其序列化为JSON。由于ModelAndView看起来像地图，在这种情况下，地图中只有一个条目，其名称为myObject，这就是JSON响应所看到的内容。为了获得你的对象，你需要只返回你的对象而不是ModelAndView，让Jackson将你的对象序列化为JSON。

What's happening is Spring MVC is taking the ModelAndView and serializing it to JSON. Since a ModelAndView just looks like a map, and in this case, you only have one entry in the map with a key name of myObject, that's what the JSON response looks at. In order to get just your object, you need to return just your object instead of a ModelAndView and let Jackson serialize your object to JSON.

而不是返回一个ModelAndView，返回一个MyObject并使用 @ResponseBody 注释该方法，因此您的控制器方法变为

Rather than returning a ModelAndView, return a MyObject and annotate the method with @ResponseBody, so your controller method becomes

@RequestMapping(value="/id/{id}", method=RequestMethod.GET, produces="application/json")
public @ResponeBody MyObject getById(@PathVariable (value="id") String id) {
    return doGetById(id);
}

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