Jackson - 如何为接口引用的反序列化指定单个实现？

Question

I want to deserialize a JSON-Object with Jackson. Because the target is an interface I need to specify which implementation should be used.

This information could be stored in the JSON-Object, using @JsonTypeInfo-Annotation. But I want to specify the implementation in source code because it's always the same.

Is this possible?

Answer 1

Use a SimpleAbstractTypeResolver :

ObjectMapper mapper = new ObjectMapper();

SimpleModule module = new SimpleModule("CustomModel", Version.unknownVersion());

SimpleAbstractTypeResolver resolver = new SimpleAbstractTypeResolver();
resolver.addMapping(Interface.class, Implementation.class);

module.setAbstractTypes(resolver);

mapper.registerModule(module);

Answer 2

There is another approach that will work if you have just single interface implementation.

public class ClassYouWantToDeserialize {
    @JsonDeserialize(as = ImplementationClass.class)
    private InterfaceClass property;
...
}

This question was answered a while ago but I want to give you another option that doesn't require to tune ObjectMapper and also much simpler then @JsonTypeInfo annotation.

Answer 3

You can use @JsonDeserialize(as = ImplementationClass.class) on the interface as well and all references will be deserialized the same way.

Note, if one of your Implementation classes is an enum, you might need @JsonFormat(shape = JsonFormat.Shape.OBJECT) on the enum as well.