自定义Jackson Serializer for Wrapper Object [英] Custom Jackson Serializer for Wrapper Object

问题描述

我有提供者界面

interface IProvider<T> {
    T locate();
}

以及包含IProvider类型字段的类（可以是其他类型的其他类型）字段）。

and a class containing a field of type IProvider (can be another type for other fields).

class MyObject {
    MyLocator<String> field;
}

我需要使用Jackson 1.7将MyObject的实例序列化为JSON。输出必须与MyObject.field是一个String（即没有ILocator的引用）相同。

I need to serialize instances of MyObject to JSON using Jackson 1.7. The output must be the same as if MyObject.field had been a String (i.e. no reference to ILocator).

我无法弄清楚如何构建自定义序列化程序需要实现这一目标。以下是我尝试用于此任务的结构：

I can't figure out how to build the custom serializer required to achieve this. Here is the structure I am trying to use for this task:

class MyLocatorSerializer extends SerializerBase<MyLocator<?>> {
    public MyLocatorSerializer() {
        super(MyLocator.class, false);
    }

    @Override
    public void serialize(MyLocator<?> a_value, JsonGenerator a_jgen,
            SerializerProvider a_provider) throws IOException, JsonGenerationException {
        // Insert code here to serialize a_value.locate(), whatever its type
    }

    @Override
    public JsonNode getSchema(SerializerProvider a_provider, Type a_typeHint)
            throws JsonMappingException {
        // What should I return here? I can't find documentation regarding the different schema types...
    }
}

自定义序列化程序将使用

The custom serializer would be registered using

SimpleModule module = new SimpleModule("MyModule", new Version(1, 0, 0, null));
module.addSerializer(new MyLocatorSerializer());
objectMapper.registerModule(module);

推荐答案

在评论之后使用混合注释的另一个答案Staxman。

Another answer using mix-in annotations following the comment from Staxman.

static class JacksonCustomModule extends SimpleModule {
    public JacksonCustomModule() {
        super("JacksonCustomModule", new Version(1, 0, 0, null));
    }

    @Override
    public void setupModule(SetupContext context) {
        context.setMixInAnnotations(IProvider.class, IProviderMixIn.class);
        super.setupModule(context);
    }

    interface IProviderMixIn<T> {
        @JsonValue
        T locate();
    }
}

激活模块：

objectMapper.registerModule(new JacksonCustomModule());

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