javascript - 改造 + GSON = 输入 "onFailure"

Question

我尝试首先使用 Retrofit 将数据获取到类(class)。但我发现我的程序将进入“onFailure”选项。

错误消息:

2020-03-07 18:54:04.499 17756-17756/com.example.apirequest I/MainActivity: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2 path $

基本上，我试图首先从 API https://api.spacexdata.com/v3/launches/ 获取“launch_year”

有人可以帮我找出我无法正确执行的原因吗？

在年级我添加了:

implementation 'com.squareup.retrofit2:retrofit:2.0.0-beta4'
implementation 'com.google.code.gson:gson:2.8.5'
implementation 'com.squareup.retrofit2:converter-gson:2.0.0-beta4'

我的代码如下:

主要 Activity :

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Retrofit retrofit = new Retrofit.Builder().
                baseUrl(APIService.urlBase)
                .addConverterFactory(GsonConverterFactory.create()).
                build();

        APIService service = retrofit.create(APIService.class);
        Call<rocketCatalog> requestModels = service.listCaralog();

        requestModels.enqueue(new Callback<rocketCatalog>() {

            @Override
            public void onResponse(Call<rocketCatalog> call, Response<rocketCatalog> response) {

                rocketCatalog catalog = response.body();

                for (Rockets rocket : catalog.rocket){
                    Log.i(TAG,String.format("%s",rocket.getLaunch_date()));
                }
            }

            @Override
            public void onFailure(Call<rocketCatalog> call, Throwable t) {
                Log.i(TAG,String.format("============= Failure =============="));
            }
        });

        LinearLayoutManager layoutManager = new LinearLayoutManager(MainActivity.this);

    }
}

API服务:

public interface APIService {

    public static final String urlBase = "https://api.spacexdata.com/v3/";

    @GET("launches")
    Call<rocketCatalog> listCaralog();

}

rocket目录:

public class rocketCatalog {

    public List<Rockets> rocket;

    public List<Rockets> getRocket() {
        return rocket;
    }

    public void setRocket(List<Rockets> rocket) {
        this.rocket = rocket;
    }
}

火箭:

public class Rockets {

    String launch_date;

    public String getLaunch_date() {
        return launch_date;
    }

    public void setLaunch_date(String launch_date) {
        this.launch_date = launch_date;
    }
}

Answer 1

您的端点返回一个 List，因此您的响应需要一个 List 类型。

public static final String urlBase = "https://api.spacexdata.com/v3/";

@GET("launches")
Call<List<Rockets>> listCaralog();

还要确保您的 Rockets 类中的字段 launch_date 存在于响应中。