Question

我正在使用一个API，它对单个用户资源的响应如下：

{
  "data": {
    "id": 11,
    "first_name": "First",
    "last_name": "Last",
    "books": {
      "data": [
        {
          "id": 13,
          "name": "Halo"
        }
      ]
    },
    "games": {
      "data": [
        {
          "id": 1,
          "name": "Halo"
        }
      ]
    }
  }
}

或类似以下用于多个用户资源：

{
  "data": [
    {
      "id": 11,
      "first_name": "First",
      "last_name": "Last",
      "books": {
        "data": [
          {
            "id": 13,
            "name": "Halo"
          }
        ]
      },
      "games": {
        "data": [
          {
            "id": 1,
            "name": "Halo"
          }
        ]
      }
    },
  ],
  "meta": {
    "pagination": {
      "total": 11,
      "count": 10,
      "per_page": 10,
      "current_page": 1,
      "total_pages": 2,
      "links": {
        "next": "http://api.###.com/users?page=2"
      }
    }
  }
}

需要注意的关键事项是：

所有资源都嵌套在data键下，单个作为对象，或多个作为对象数组。这包括嵌套资源，例如上面示例中的书籍和游戏。
我需要能够为我的分页例程检索meta键的值

用户模型

public class User extends BaseModel {

    public Integer id;
    public String firstName;
    public String lastName;

    public List<Book> books; // These will not receive the deserialized 
    public List<Game> games; // JSON due to the parent data key

}

自定义JSON反序列化程序

public class ItemTypeAdapterFactory implements TypeAdapterFactory {

    public <T> TypeAdapter<T> create(Gson gson, final TypeToken<T> type) {

        final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
        final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);

        return new TypeAdapter<T>() {

            public void write(JsonWriter out, T value) throws IOException {
                delegate.write(out, value);
            }

            public T read(JsonReader in) throws IOException {

                JsonElement jsonElement = elementAdapter.read(in);
                if (jsonElement.isJsonObject()) {
                    JsonObject jsonObject = jsonElement.getAsJsonObject();
                    // If the data key exists and is an object or array, unwrap it and return its contents
                    if (jsonObject.has("data") && (jsonObject.get("data").isJsonObject() || jsonObject.get("data").isJsonArray())) {
                        jsonElement = jsonObject.get("data");
                    }
                }

                return delegate.fromJsonTree(jsonElement);
            }
        }.nullSafe();
    }
}

这一切都运行正常，但我无法弄清楚如何访问meta密钥进行分页。

理想情况下，我会让Gson反序列化对以下POJO的响应：

public class ApiResponse {
    public Object data;
    public Meta meta
}

我可以将response字段转换为响应回调中的正确类型，如下所示：

Map<String, String> params = new HashMap<String, String>();
params.put("include", "books,games");
ApiClient.getClient().authenticatedUser(params, new ApiClientCallback<ApiResponse>() {
    @Override
    public void failure(RestError restError) {
        Log.d("TAG", restError.message);
    }

    @Override
    public void success(ApiResponse response, Response rawResponse) {
        User user = (User) response.data; // Cast data field to User type
        Log.d("TAG", user.firstName);
        Log.d("TAG", "Total pages" + response.meta.pagination.total.toString()); // Still have access to meta key data
    }
});

但data对象的ApiResponse字段为null。

我的Java非常生疏，我不知道这是否可能，也不知道如何正确理解，任何帮助都会非常感激。

使用Retrofit和Gson将JSON反序列化为POJO

用户模型

自定义JSON反序列化程序

0 个答案: