无法构建 - Jackson 的实例 [英] Cannot construct instance of - Jackson

问题描述

我正在使用 Jackson 并且遇到问题，当我尝试反序列化对象时，出现以下错误:

I am using Jackson and I'm having problems, when I try to deserialize an Object I get the following error:

com.fasterxml.jackson.databind.JsonMappingException: 
    Can not construct instance of net.MyAbstractClass, 
    problem: abstract types either need to be mapped to concrete types, 
        have custom deserializer, or be instantiated with additional type information

我的属性有问题:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.WRAPPER_OBJECT, property = "@id")
@JsonSubTypes({ @JsonSubTypes.Type(value = MyAbstractClass.class, name = "MyAbstractClass") })
@ManyToOne
private MyAbstractClass object;

有人可以帮我吗?

推荐答案

您不能实例化抽象类，Jackson 也不能.您应该向 Jackson 提供有关如何使用具体类型实例化 MyAbstractClass 的信息.

You cannot instantiate an abstract class, Jackson neither. You should give Jackson information on how to instantiate MyAbstractClass with a concrete type.

在stackoverflow上看到这个答案:Jackson JSON 库:如何实例化包含抽象字段的类

See this answer on stackoverflow: Jackson JSON library: how to instantiate a class that contains abstract fields

也许还可以参见 Jackson 多态反序列化

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