针对特定类别中的特定类型的自定义Jackson Serializer [英] Custom Jackson Serializer for a specific type in a particular class

问题描述

杰克逊是否允许仅针对特定类别的特定类型进行自定义序列化？

Is there a way by which Jackson allows custom serialization for a specific type only in a particular class?

这是我的场景：
我有ClassA .java是这样的：

Here is my scenario: I have ClassA.java which is something like:

public Class ClassA {

    byte[] token;
    String name;

    public getToken() {
        return token;
    }

    public setToken(byte[] newToken) {
        token = newToken;
    }

    public getName() {
        return name;
    }

    public setName(String newName) {
        name = newName;
    }
}

我无法访问此类，因为它是在一个外部罐子里。但是，我想以特定方式在此处序列化令牌字节数组。我已经创建了一个自定义序列化程序来执行该操作，并尝试以杰克逊文档中提到的所有方式将其添加到映射器。

I do not have access to this class as it is in an external jar. However, I want to serialize the token byte array here in a particular manner. I have created a Custom serializer that does that and tries adding it to the mapper in all the ways mentioned in Jackson docs.

public class ByteArrayJacksonSerializer extends JsonSerializer<byte[]> {

    public void serialize(byte[] value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException {

        String token = doMyThing(value);
        jgen.writeString(token);
    }
}

在mapper中，类似这样：

And in mapper, something like this:

public class MyObjectMapper extends ObjectMapper {

    CustomSerializerFactory sf = new CustomSerializerFactory();
    sf.addGenericMapping(byte[].class, new ByteArrayJacksonSerializer());
    this.setSerializerFactory(sf);

    and some more code here...
}

但是我一般只能用于byte []，而不能用于ClassA中的ONLY byte []。有没有办法让杰克逊知道这个自定义序列化器必须只用于ClassA中byte []类型的字段，并且为所有其他类做自己的序列化？

However I can do it only for byte[] in general, and not for ONLY byte[] in ClassA. Is there a way to let Jackson know that this custom serializer must be used ONLY for fields of byte[] type in ClassA, and to do serialization it's own way for all other classes?

推荐答案

您应该使用 MixIn 功能。在您的示例中，您必须创建新接口：

You should use MixIn feature. In your example you have to create new interface:

interface ClassAMixIn {

    @JsonSerialize(using = ByteArrayJacksonSerializer.class)
    byte[] getToken();
}

指定给定属性的自定义序列化程序。现在我们必须配置 ObjectMapper

which specifies custom serializer for given property. Now we have to configure ObjectMapper

ObjectMapper mapper = new ObjectMapper();
mapper.addMixInAnnotations(ClassA.class, ClassAMixIn.class);

您的自定义序列化程序仅用于序列化 ClassA中的字节数组属性/ code>。

Your custom serializer will be used only for serializing byte array property in ClassA.

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