改造将标签添加到原始请求对象

Question

我正在尝试解决一个问题，我将进行几个异步调用，并根据原始请求执行一项任务。为了解决这个问题，我尝试为每个请求添加一个标签，然后在成功响应后，我可以获取标签并根据标签采取行动。在这里，我只使用 TAG 来识别原始请求。

问题

在调用入队方法之​​前，我将标记设置为原始请求。但是当我在成功的回调中得到响应时，我得到了我没有设置的不同标签。不知何故，请求对象本身作为标记对象出现在那里。不知道怎么弄？？？

请检查下面的代码-

GitHubService gitHubService = GitHubService.retrofit.create(GitHubService.class);
                final Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit");

                // Set the string tag to the original request object.
                call.request().newBuilder().tag("hello").build();


                call.enqueue(new Callback<List<Contributor>>() {
                    @Override
                    public void onResponse(Call<List<Contributor>> call, Response<List<Contributor>> response) {
                        Log.d("tag", response.raw().request().tag().toString());
                        // I'm getting Request{method=GET, url=https://api.github.com/repos/square/retrofit/contributors, tag=null} as the value of the tag. WHY????
                        final TextView textView = (TextView) findViewById(R.id.textView);
                        textView.setText(response.body().toString());
                    }
                    @Override
                    public void onFailure(Call<List<Contributor>> call, Throwable t) {
                        final TextView textView = (TextView) findViewById(R.id.textView);
                        textView.setText("Something went wrong: " + t.getMessage());
                    }
                });

有人可以指出我在这里做错了什么。任何帮助，将不胜感激。

Answer 1

这个解决方案显然是一个 hack，但它确实有效。

假设您像这样创建改造服务：

 public <S> S createService(Class<S> serviceClass) {

    // Could be a simple "new"
    Retrofit.Builder retrofitBuilder = getRetrofitBuilder(baseUrl); 

    // Could be a simple "new"
    OkHttpClient.Builder httpClientBuilder = getOkHttpClientBuilder();  

    // Build your OkHttp client
    OkHttpClient httpClient = httpClientBuilder.build();

    Retrofit retrofit = retrofitBuilder.client(httpClient).build();

    return retrofit.create(serviceClass);
}

您需要向 Retrofit 实例添加一个新的 CallFactory，因此它每次都会添加一个标签。由于标签是只读的，我们将使用一个只包含一个元素的 Object 数组，您稍后可以更改它。

Retrofit retrofit = retrofitBuilder.client(httpClient).callFactory(new Call.Factory() {
        @Override
        public Call newCall(Request request) {

            request = request.newBuilder().tag(new Object[]{null}).build();

            Call call = httpClient.newCall(request);

            // We set the element to the call, to (at least) keep some consistency
            // If you want to only have Strings, create a String array and put the default value to null;
            ((Object[])request.tag())[0] = call;

            return call;
        }
    }).build();

现在，在创建调用后，您将能够更改标签的内容：

((Object[])call.request().tag())[0] = "hello";

Answer 2

对我来说，这段代码是有效的

val CLIENT: OkHttpClient = OkHttpClient.Builder().apply {
    addInterceptor(TagInterceptor())
}.build()

val SERVER_API: ServerApi = Retrofit.Builder()
    .client(CLIENT)
    .baseUrl(BASE_URL)
    .build()
    .create(ServerApi::class.java)

interface ServerApi {

    @GET("api/notifications")
    @Tag("notifications")
    suspend fun getNotifications(): ResponseBody
}

@Target(AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY_GETTER, AnnotationTarget.PROPERTY_SETTER)
@Retention(AnnotationRetention.RUNTIME)
annotation class Tag(val value: String)

internal class TagInterceptor : Interceptor {

    override fun intercept(chain: Interceptor.Chain): Response {
        val request = chain.request()
        val builder = request.newBuilder()
        request.tag(Invocation::class.java)?.let {
            it.method().getAnnotation(Tag::class.java)?.let { tag ->
                builder.tag(tag.value)
            }
        }
        return chain.proceed(builder.build())
    }
}

然后通过标签取消

fun OkHttpClient.cancelAll(tag: String) {
    for (call in dispatcher().queuedCalls()) {
        if (tag == call.request().tag()) {
            call.cancel()
        }
    }
    for (call in dispatcher().runningCalls()) {
        if (tag == call.request().tag()) {
            call.cancel()
        }
    }
}

CLIENT.cancelAll("notifications")

Answer 3

请求上已经有标签。您可以通过以下代码获取：

val invocation: Invocation? = call.request().tag(Invocation::class.java)
        if (invocation != null) {
            Timber.d("tag--${invocation.method().name}}-------${invocation.arguments()}")
        }