Retrofit2 Android:应为BEGIN_ARRAY，但在第1行第2列路径$处为BEGIN_OBJECT

Question

我知道这已经不是第一次有人问这个问题了，但是在Treverfit2中，我找不到解决我问题的正确方法。我看了一个在线教程，效果很好。当我将相同的代码应用到我自己的endpoint时，我得到了这个异常:java.lang.IllegalStateException：应该是BEGIN_ARRAY但在第1行第2列是BEGIN_OBJECT，路径$我不知道如何解决这个问题。

接口：

public interface MyApiService {

// Is this right place to add these headers?
@Headers({"application-id: MY-APPLICATION-ID",
        "secret-key: MY-SECRET-KEY",
        "application-type: REST"})
@GET("Music")
Call<List<Music>> getMusicList();



Retrofit retrofit = new Retrofit.Builder()
        .baseUrl(MySettings.REST_END_POINT)
        .addConverterFactory(GsonConverterFactory.create())
        .build();
}

MyApiService service = MyApiService.retrofit.create(MyApiService.class);
Call<List<Music>> call = service.getMusicList();
call.enqueue(new Callback<List<Music>>() {

    @Override
    public void onResponse(Call<List<Music>> call, Response<List<Music>> response) {
        Log.e("MainActivity", response.body().
    }

    @Override
    public void onFailure(Call<List<Music>> call, Throwable t) {
        Log.e("MainActivity", t.toString());
    }
});

[
{
    "login": "JakeWharton",
    "id": 66577,
    "avatar_url": "https://avatars.githubusercontent.com/u/66577?v=3",
    "gravatar_id": "",
    "url": "https://api.github.com/users/JakeWharton",
    "html_url": "https://github.com/JakeWharton",
    "followers_url": "https://api.github.com/users/JakeWharton/followers",
    "following_url": "https://api.github.com/users/JakeWharton/following{/other_user}",
    "gists_url": "https://api.github.com/users/JakeWharton/gists{/gist_id}",
    "starred_url": "https://api.github.com/users/JakeWharton/starred{/owner}{/repo}",
    "subscriptions_url": "https://api.github.com/users/JakeWharton/subscriptions",
    "organizations_url": "https://api.github.com/users/JakeWharton/orgs",
    "repos_url": "https://api.github.com/users/JakeWharton/repos",
    "events_url": "https://api.github.com/users/JakeWharton/events{/privacy}",
    "received_events_url": "https://api.github.com/users/JakeWharton/received_events",
    "type": "User",
    "site_admin": false,
    "contributions": 741
},
{....

但这个不是：

{
"offset": 0,
"data": [
    {
        "filename": "E743_1458662837071.mp3",
        "created": 1458662854000,
        "publicUrl": "https://api.backendless.com/dbb77803-1ab8-b994-ffd8-65470fa62b00/v1/files/music/E743_1458662837071.mp3",
        "___class": "Music",
        "description": "",
        "likeCount": 0,
        "title": "hej Susanne. ",
        "ownerId": "E743756F-E114-6892-FFE9-BCC8C072E800",
        "updated": null,
        "objectId": "DDD8CB3D-ED66-0D6F-FFA5-B14543ABC800",
        "__meta": "{\"relationRemovalIds\":{},\"selectedProperties\":[\"filename\",\"created\",\"publicUrl\",\"___class\",\"description\",\"likeCount\",\"title\",\"ownerId\",\"updated\",\"objectId\"],\"relatedObjects\":{}}"
    },
    {...

我的音乐课：

public class Music {

   private String ownerId;
   private String filename;
   private String title;
   private String description;
   private String publicUrl;
   private int likeCount;

   // Getters & Setters

}

Answer 1

当您说“此代码正在使用此有效负载：...但不使用此有效负载：...”时这是预料之中的事情，也是应该这样做的。实际上，错误消息告诉您，在将json转换为java对象时，调用需要json中的一个数组，但却得到了一个对象。

此呼叫：

@GET("Music")
Call<List<Music>> getMusicList();

需要一个music对象列表，这就是它与JSON一起工作的原因：

[
  {
    "login": "JakeWharton",
    ...
  },
  ...
]

@GET("Music")
Call<MusicList> getMusicList();

public class MusicList {
  @SerializedName("data")
  private List<Music> musics;
  // ...
}

我假设data数组是music对象的列表，但我确实注意到jsons是完全不同的。你可能也需要调整一下，但我想你已经明白了。