OkHttp API 速率限制

Question

OkHttp 是否有一种符合 api 速率请求限制的集成方式，还是必须在外部实现？无论哪种情况，都可以提示从哪里开始。

Answer 1

interceptor 结合来自 Guava 的 RateLimiter 是避免接收 429 HTTP 代码的好方法。

假设我们希望每秒调用 3 次：

import java.io.IOException;

import com.google.common.util.concurrent.RateLimiter;

import okhttp3.Interceptor;
import okhttp3.Response;

public class RateLimitInterceptor implements Interceptor {
    private RateLimiter rateLimiter = RateLimiter.create(3);

    @Override
    public Response intercept(Chain chain) throws IOException {
        rateLimiter.acquire(1);
        return chain.proceed(chain.request());
    }
}

Answer 2

正如@jesse-wilson 所说，您可以使用OkHttp Interceptors 做到这一点

这是一个例子。首先定义一个自定义拦截器。当达到速率限制时，我调用的 api 会以 HTTP 代码 429 响应。您需要在自己的 api 中检查指示速率错误的特定 HTTP 代码或标头，并休眠适当的时间。

public class RateLimitInterceptor implements Interceptor {

    public RateLimitInterceptor() {
    }

    @Override
    public Response intercept(Chain chain) throws IOException {

        Response response = chain.proceed(chain.request());

        // 429 is how the api indicates a rate limit error
        if (!response.isSuccessful() && response.code() == 429) {
            System.err.println("Cloudant: "+response.message());

            // wait & retry
            try {
                System.out.println("wait and retry...");
                Thread.sleep(1000);
            } catch (InterruptedException e) {}

            response = chain.proceed(chain.request());
        }

        return response;
    }
}

接下来将拦截器添加到您构建 OkHttp 请求的位置。这是我的构建器的示例...

public static Response fetchPaged(HttpUrl url) throws IOException {
        OkHttpClient client = new OkHttpClient.Builder()
                .addInterceptor(new BasicAuthInterceptor(username, password))
                .addInterceptor(new RateLimitInterceptor())
                .build();

        Request request = new Request.Builder()
                .url(url)
                .build();

        return client
                .newCall(request)
                .execute();
    }

Answer 3

您可以构建一个interceptor 来跟踪发出的请求，如果速率太高，可能会限制或失败请求。

Answer 4

我也有这个问题。 通过邮寄上传大文件时，我想要限制速率。我阅读了 OkHttp 拦截器代码。并且 find 可以限制正文写入以限制上传速率。

public class RateLimitingRequestBody extends RequestBody {

private MediaType mContentType;
private File mFile;
private int mMaxRate;    // ms/bit

private RateLimitingRequestBody(@Nullable final MediaType contentType, final File file, int rate){
    mContentType = contentType;
    mFile = file;
    mMaxRate = rate;
}

@Override
public MediaType contentType() {
    return mContentType;
}

@Override
public void writeTo(BufferedSink sink) throws IOException {

    Source source = null;

    try {
        source = Okio.source(mFile);
        writeAll(sink, source);
    } catch (InterruptedException e) {
        e.printStackTrace();
    } finally {
        Util.closeQuietly(source);
    }
}


public long writeAll(BufferedSink sink, Source source) throws IOException, InterruptedException {
    if (source == null) {
        throw new IllegalArgumentException("source == null");
    } else {
        long totalBytesRead = 0L;

        long readCount;
        long start = System.currentTimeMillis();
        while((readCount = source.read(sink.buffer(), 8192L)) != -1L) {
            totalBytesRead += readCount;
            sink.emitCompleteSegments();

            long time = System.currentTimeMillis();
            if(time == start) continue;
            long rate = (totalBytesRead * 8) / (time - start);
            NLog.v("writeAll","totalBytesRead:"+totalBytesRead+"B "+ " Rate:"+rate*1000+"bits");

            if(rate > mMaxRate/1000){
                int sleep = (int) (totalBytesRead * 8 * 1000 / mMaxRate - (time - start));
                NLog.d("writeAll", "sleep:"+sleep);
                Thread.sleep(sleep+50);
            }
        }

        long end = System.currentTimeMillis();
        long rate = (totalBytesRead * 8 * 1000) / ((end - start));
        NLog.e("writeAll","totalBytesRead:"+totalBytesRead+"B "+ " Rate:"+rate+"bits"+" total time:"+(end-start));
        return totalBytesRead;
    }
}


public static RequestBody createRequestBody(@Nullable final MediaType contentType, final File file, int rate) {
    if (file == null) {
        throw new NullPointerException("content == null");
    } else {
        return new RateLimitingRequestBody(contentType, file, rate);
    }
}

}

也许这对你有帮助。