我有一个类层次结构。在它的顶部有一个抽象AnswerUnit类。有两种继承类：OpenQuestionAnswer和MultipleChoiceQuestionAnswer。

I have a class hierarchy. On the top of it there is a an abstract AnswerUnit class. There are two inheriting classes: OpenQuestionAnswer and MultipleChoiceQuestionAnswer.

我有发送数据（序列化到JSON对象）到服务器AJAX请求和控制的方法来处理它的.jsp的形式。

I have a .jsp form that sends data (object serialized to JSON) to server with AJAX request and a method in controller to handle it.

@RequestMapping(value = "/test", method = RequestMethod.POST)
    public @ResponseBody
    String testPostMethod(@RequestBody
    OpenQuestionAnswer answer) {
        return "home";
    }

我希望能够采取AnswerUnit回答作为参数（抽象类型，而不是具体类型，这样我就可以从不同的角度处理请求，一种方法）。当我尝试这样做有一个问题 - 服务器respose是

I would like to be able to take "AnswerUnit answer" as the argument (abstract type instead of concrete type, so I could handle request from different views with one method). When I try to do it there is a problem - server respose is

400错误的请求，他要求客户端发送的是语法不正确。

我认为，原因在于春（杰克逊？）是不是能够找出具体的类，他应该创建和使用。 在客户端，我知道我发送到服务器是什么类型的类。 什么是正确的方法来判断哪些具体的类应创建并充满了我的请求，服务器？

I think that the reason is that Spring (Jackson?) isn't able to find out which concrete class he should create and use. On the client side I know what type of class I send to server. What is the proper way to tell server which concrete class should be created and filled with my request?

推荐答案

我想我下旬响应，但无论如何：）

I guess I'm late with response, but anyway:)

http://wiki.fasterxml.com/JacksonAnnotations

您可以使用此杰克逊多态类型处理

You can have this using Jackson Polymorphic type handling

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type")
@JsonSubTypes(value = {
    @JsonSubTypes.Type(name = "answer", value = OpenQuestionAnswer.class),
    @JsonSubTypes.Type(name = "multiple", value = MultipleChoiceQuestionAnswer.class)
})
public class AnswerUnit
...

但是，你需要类型字段添加到您的客户端的JSON。

But you would need to add "type" field to your client JSON.