卢克菲特2 Android: 预期的 BEGIN_ARRAY，但是在第1行第2列路径 $处是 BEGIN_OBJECT

我知道这不是第一次有人问我这个问题，但是我无法找到正确的方法来解决我的问题。我跟踪了一个在线教程，效果很好。当我应用相同的代码到我自己的端点，我得到这个例外: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $我不知道如何解决这个问题。

界面:

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();
}

客户端代码:

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());
}
});

使用这个负载的代码:

[
{
"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
},
{....

但不是这个:

{
"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


}

127578

小开

最佳答案

When you say "This code is working with this payload:... but not with this one:..." that's expected and that's how it's suppose to work. In fact the error message tells you that while converting the json to a java object the call expected an array in the json but got an object instead.

This call:

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

expects a list of Music objects, that's why it works with the json:

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

Because the json itself is an array of your Music objects (Retrofit can convert between json arrays to java lists). For the second json you have just an object and not an array (notice the lack of [...]). For this you need to create another call with another model that maps to that json. Let's assume you've named the model MusicList. Here's how the call could look like:

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

(Note that you might need to change the method name if you want to keep both the first call and this one).

The MusicList model can look something like this:

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

I'm assuming that the data array is a list of Music objects, but I did notice that the jsons are completely different. You might need to adapt this as well, but I think you get the picture here.

小开

I had this problem. It's because the payload is an object instead of an array of objects. So I removed List.

Code Example

UserAPI.java

public interface UserAPI {
@GET("login/cellphone")
Call<LoginResponse> login(@Query("phone") String phone,
@Query("password") String password);
}

Call code

Retrofit retrofit = new Retrofit
.Builder()
.addConverterFactory(GsonConverterFactory.create())
.baseUrl(Constant.CLOUD_MUSIC_API_BASE_URL)
.build();


UserAPI userAPI = retrofit.create(UserAPI.class);


userAPI.login(phone, password).enqueue(new Callback<LoginResponse>() {
@Override
public void onResponse(Call<LoginResponse> call, Response<LoginResponse> response) {
System.out.println("onResponse");
System.out.println(response.body().toString());
}


@Override
public void onFailure(Call<LoginResponse> call, Throwable t) {
System.out.println("onFailure");
System.out.println(t.fillInStackTrace());
}
});

小开

In my case the issue was about my return type of this function was wrong I was returning retrofit2.Call<List<GamesModel>> this error means that GSON was expecting an array to come back from your server.

I just remove the List and now it's working fine