Gson：处理可以返回不同原始类型的json对象字段？

Question

An API my application is communicating with sends responses that look like this:

{
    id:12345,
    active:1
}

The problem is that older versions of the API sends the response field as a boolean value rather than an int like so

{
    id:12345,
    active:false,
}

With Gson, how can I handle both with no knowledge of which version will be returned?

Answer 1

Register a CustomDeserializer for boolean and when ever a boolean is encountered inside any object, gson will try to deserialize with the rules that you defined.

@Data
class JsonTestClass {
    Boolean active = new Boolean(true);
    Integer id;
}

class BooleanJsonDeserializer implements JsonDeserializer<Boolean> {
    @Override
    public Boolean deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
            throws JsonParseException {
        JsonPrimitive jsonPrimitive = json.getAsJsonPrimitive();
        if (jsonPrimitive.isBoolean()) {
            return jsonPrimitive.getAsBoolean();
        } else {
            return jsonPrimitive.getAsInt() == 0 ? false : true;
        }
    }
}

// TempJson
public static void main(String[] args) throws Exception {
    Gson gson = new GsonBuilder()
            .registerTypeAdapter(Boolean.class, new BooleanJsonDeserializer()).create();

    System.out.println(gson.fromJson("{id:12345,active:1}", JsonTestClass.class).getActive());
    System.out.println(gson.fromJson("{id:12345,active:0}", JsonTestClass.class).getActive());
    System.out.println(gson.fromJson("{id:12345,active:false}", JsonTestClass.class).getActive());
    System.out.println(gson.fromJson("{id:12345,active:true}", JsonTestClass.class).getActive());
}

Output:

true
false
false
true

Answer 2

PFB the way to handle this.

public static void main(String[] args) {
    Gson gson = new Gson();
    JsonObject obj = gson.fromJson("{    id:12345,    active:1}", JsonObject.class);
    JsonPrimitive prim = obj.get("active").getAsJsonPrimitive();
    if(prim.isBoolean()){
        System.out.println("boolean");
    }else{
        System.out.println("number");
    }
}