Retrofit 2 4xx 错误的同步调用错误处理

Question

我正在使用 android-priority-jobqueue 并且我使用改造来对我的 rest api 进行同步调用，但我不确定如何处理诸如 401 Unauthorized 错误之类的错误，我发回 json 来说明错误。进行异步调用时很简单，但我正在为作业经理调整我的应用程序。下面是 IO 异常的简单尝试捕获，但是 401 的 422 等？如何做到这一点？

try {
    PostService postService = ServiceGenerator.createService(PostService.class);
    final Call<Post> call = postService.addPost(post);
    Post newPost = call.execute().body();

    // omitted code here

} catch (IOException e) {
    // handle error
}

编辑

改造响应对象的使用对我来说是关键，返回改造响应对象让我能够

Response<Post> response = call.execute();

if (response.isSuccessful()) {
    // request successful (status code 200, 201)
    Post result = response.body();

    // publish the post added event
    EventBus.getDefault().post(new PostAddedEvent(result));
} else {
    // request not successful (like 400,401,403 etc and 5xx)
    renderApiError(response);
}

Answer 1

检查响应代码并显示相应的消息。

试试这个：

 PostService postService = ServiceGenerator.createService(PostService.class);
 final Call<Post> call = postService.addPost(post);

Response<Post> newPostResponse = call.execute();

// Here call newPostResponse.code() to get response code
int statusCode = newPostResponse.code();
if(statusCode == 200)
    Post newPost = newPostResponse.body();
else if(statusCode == 401)
    // Do some thing... 

Answer 2

对每个响应都进行 401 检查并不是一个很好的方法。相反，可以在基础级别应用此检查，即在为 Retrofit 创建对象时，通过拦截器。看看：

public synchronized static Retrofit getClientWithRetry(final Context ctx) {
    if (clientWithRetry == null) {
        Interceptor responseCodeInterceptor = new Interceptor() {
            @Override
            public Response intercept(Chain chain) throws IOException {
                Request request = chain.request();
                Response response = chain.proceed(request);
                if (response.code() == 401) {
                    Log.d(LOG_TAG, "Intercepted Req: " + response.toString());
                    Response r = retryWithFreshToken(request, chain);
                    return r;
                }
                return response;
            }
        };

        int cacheSize = 10 * 1024 * 1024; // 10 MB
        Cache cache = new Cache(ctx.getCacheDir(), cacheSize);

        HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
        logging.setLevel(HttpLoggingInterceptor.Level.BODY);
        OkHttpClient client = new OkHttpClient.Builder()
                .addInterceptor(logging)
                .addInterceptor(responseCodeInterceptor)
                .cache(cache)
                .build();

        Retrofit.Builder builder = new Retrofit.Builder()
                .baseUrl(API_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .client(client);
        clientWithRetry = builder.build();
    }
    return clientWithRetry;
}

如果在内部观察到 401，则可以发出新的链式请求并且可以获取令牌。可以完成原始请求的帖子。取自Retrofit retry tutorial。