改造 api 获取请求不触发回调方法答案

【问题标题】：retrofit api get request not firing the calback methods改造 api 获取请求不触发回调方法
【发布时间】：2021-08-05 13:42:54
【问题描述】：

我遇到了改造问题：我试图向这个 API 发出 get 请求：https://test.spaceflightnewsapi.net/api/v2/articles

但不知何故，改造中的回调方法没有被调用。我在 logcat/ 中得到了这个唯一与改造相关的东西（okkhttp）：

 I/okhttp.OkHttpClient: --> GET https://test.spaceflightnewsapi.net/api/v2/articles
 I/okhttp.OkHttpClient: --> END GET

这是我的api接口：

public interface SpaceNewsApi {
    String BASE_URL = "https://test.spaceflightnewsapi.net/api/v2/";
    @GET("articles")
    Call<List<SpaceNews>> getSpaceNewsArticles();
}

这是改造客户端（请注意，我将使用两个 api 进行改造，这就是为什么我使用两种方法来构建它），我还添加了一个日志拦截器，我已经将级别更改为不同类型，但只有上面的内容是我每次在与改造相关的日志中收到的消息

public class RetrofitClients {
    private static RetrofitClients instance = null;
    private SpaceNewsApi mySpaceNewsApi = null;
    private LaunchLibraryApi myLaunchLibraryApi = null;

    public static synchronized RetrofitClients getInstance() {
        if (instance == null) {
            instance = new RetrofitClients();
        }
        return instance;
    }

    public SpaceNewsApi getMySpaceNewsApi() {
        if(mySpaceNewsApi == null) {
            Retrofit retrofit = new Retrofit.Builder().baseUrl(SpaceNewsApi.BASE_URL)
                    .client(getHttpClient())
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
            mySpaceNewsApi = retrofit.create(SpaceNewsApi.class);
        }
        return mySpaceNewsApi;
    }

    public  LaunchLibraryApi getMyLaunchLibraryApi(){
        if(myLaunchLibraryApi == null) {
            Retrofit retrofit = new Retrofit.Builder().baseUrl(LaunchLibraryApi.BASE_URL)
                    .client(getHttpClient())
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
            myLaunchLibraryApi = retrofit.create(LaunchLibraryApi.class);
        }
        return myLaunchLibraryApi;
    }

    public static OkHttpClient getHttpClient() {
        HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
        logging.setLevel(HttpLoggingInterceptor.Level.HEADERS);
        //TODO : remove logging interceptors as it is to be used for development purpose
        OkHttpClient client = new OkHttpClient.Builder()
                .connectTimeout(300, TimeUnit.SECONDS)
                .readTimeout(300, TimeUnit.SECONDS)
                .addInterceptor(logging)
                .build();
        return client;
    }
}

我在我的主要活动 onCreate 方法中调用所有这些，如下所示：

 //testing Api Call
        Call<List<SpaceNews>> call = RetrofitClients.getInstance().getMySpaceNewsApi().getSpaceNewsArticles();
        call.enqueue(new Callback<List<SpaceNews>>() {

            @Override
            public void onResponse(Call<List<SpaceNews>> call, Response<List<SpaceNews>> response) {
                Log.d("gotApiData","got it");

            }

            @Override
            public void onFailure(Call<List<SpaceNews>> call, Throwable t) {
                Log.d("gotError","not got it");
                t.printStackTrace();
            }

        });

我怎样才能让这个工作，我会很感激任何建议！

【问题讨论】：

标签： java android api android-studio retrofit2

【解决方案1】：

我认为问题出在 RetrofitClients 类上，在添加私有构造函数并从 get***Api 方法中移动大部分代码之后似乎可以解决问题。

这里是修改后的 RetrofitClients：

public class RetrofitClients {
    private static RetrofitClients instance = null;
    private SpaceNewsApi mySpaceNewsApi = null;
    private LaunchLibraryApi myLaunchLibraryApi = null;

    private RetrofitClients(){
        if(mySpaceNewsApi == null) {
            Retrofit retrofit = new Retrofit.Builder().baseUrl(SpaceNewsApi.BASE_URL)
                    .client(getHttpClient())
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
            mySpaceNewsApi = retrofit.create(SpaceNewsApi.class);
        }
        if(myLaunchLibraryApi == null) {
            Retrofit retrofit = new Retrofit.Builder().baseUrl(LaunchLibraryApi.BASE_URL)
                    .client(getHttpClient())
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
            myLaunchLibraryApi = retrofit.create(LaunchLibraryApi.class);
        }
    }

    public static synchronized RetrofitClients getInstance() {
        if (instance == null) {
            instance = new RetrofitClients();
        }
        return instance;
    }

    public SpaceNewsApi getMySpaceNewsApi() {

        return mySpaceNewsApi;
    }

    public  LaunchLibraryApi getMyLaunchLibraryApi(){

        return myLaunchLibraryApi;
    }

    public static OkHttpClient getHttpClient() {
        HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
        logging.setLevel(HttpLoggingInterceptor.Level.HEADERS);
        //TODO : remove logging interceptors as it is to be used for development purpose
        OkHttpClient client = new OkHttpClient.Builder()
                .connectTimeout(300, TimeUnit.SECONDS)
                .readTimeout(300, TimeUnit.SECONDS)
                .addInterceptor(logging)
                .build();
        return client;
    }
}

【讨论】：