Gson：如何更改Enum的输出 [英] Gson: How to change output of Enum

问题描述

我有这个枚举：

I've this enum:

enum RequestStatus {
  OK(200), NOT_FOUND(400);

  private final int code;

  RequestStatus(int code) {
    this.code = code;
  }

  public int getCode() {
    return this.code;
  }
};

在我的Request-class中，我有这个字段： private RequestStatus status 。

and in my Request-class, I have this field: private RequestStatus status.

当使用Gson将Java对象转换为JSON时，结果如下所示：

When using Gson to convert the Java object to JSON the result is like:

"status": "OK"

我改变我的GsonBuilder或我的Enum对象给我一个输出，如：

How can I change my GsonBuilder or my Enum object to give me an output like:

"status": {
  "value" : "OK",
  "code" : 200
}

推荐答案

您可以使用像这样的东西：

You can use something like this:

GsonBuilder builder = new GsonBuilder();
builder.registerTypeAdapterFactory(new MyEnumAdapterFactory());

或更简单（如Jesse Wilson所示）：

or more simply (as Jesse Wilson indicated):

GsonBuilder builder = new GsonBuilder();
builder.registerTypeAdapter(RequestStatus.class, new MyEnumTypeAdapter());

和

public class MyEnumAdapterFactory implements TypeAdapterFactory {

    @Override
    public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> type) {
            Class<? super T> rawType = type.getRawType();
            if (rawType == RequestStatus.class) {
                return new MyEnumTypeAdapter<T>();
            }
            return null;
    }

    public class MyEnumTypeAdapter<T> extends TypeAdapter<T> {

         public void write(JsonWriter out, T value) throws IOException {
              if (value == null) {
                   out.nullValue();
                   return;
              }
              RequestStatus status = (RequestStatus) value;
              // Here write what you want to the JsonWriter. 
              out.beginObject();
              out.name("value");
              out.value(status.name());
              out.name("code");
              out.value(status.getCode());
              out.endObject();
         }

         public T read(JsonReader in) throws IOException {
              // Properly deserialize the input (if you use deserialization)
              return null;
         }
    }

}

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