android - 在后台收听下载进度

Question

我尝试按照此文件作为教程来收听下载进度 https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/Progress.java

/*
 * Copyright (C) 2015 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.recipes;

import java.io.IOException;
import okhttp3.Interceptor;
import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;
import okio.Buffer;
import okio.BufferedSource;
import okio.ForwardingSource;
import okio.Okio;
import okio.Source;

public final class Progress {

  public void run() throws Exception {
    Request request = new Request.Builder()
        .url("https://publicobject.com/helloworld.txt")
        .build();

    final ProgressListener progressListener = new ProgressListener() {
      boolean firstUpdate = true;

      @Override public void update(long bytesRead, long contentLength, boolean done) {
        if (done) {
          System.out.println("completed");
        } else {
          if (firstUpdate) {
            firstUpdate = false;
            if (contentLength == -1) {
              System.out.println("content-length: unknown");
            } else {
              System.out.format("content-length: %d\n", contentLength);
            }
          }

          System.out.println(bytesRead);

          if (contentLength != -1) {
            System.out.format("%d%% done\n", (100 * bytesRead) / contentLength);
          }
        }
      }
    };

    OkHttpClient client = new OkHttpClient.Builder()
        .addNetworkInterceptor(new Interceptor() {
          @Override public Response intercept(Chain chain) throws IOException {
            Response originalResponse = chain.proceed(chain.request());
            return originalResponse.newBuilder()
                .body(new ProgressResponseBody(originalResponse.body(), progressListener))
                .build();
          }
        })
        .build();

    try (Response response = client.newCall(request).execute()) {
      if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

      System.out.println(response.body().string());
    }
  }

  public static void main(String... args) throws Exception {
    new Progress().run();
  }

  private static class ProgressResponseBody extends ResponseBody {

    private final ResponseBody responseBody;
    private final ProgressListener progressListener;
    private BufferedSource bufferedSource;

    ProgressResponseBody(ResponseBody responseBody, ProgressListener progressListener) {
      this.responseBody = responseBody;
      this.progressListener = progressListener;
    }

    @Override public MediaType contentType() {
      return responseBody.contentType();
    }

    @Override public long contentLength() {
      return responseBody.contentLength();
    }

    @Override public BufferedSource source() {
      if (bufferedSource == null) {
        bufferedSource = Okio.buffer(source(responseBody.source()));
      }
      return bufferedSource;
    }

    private Source source(Source source) {
      return new ForwardingSource(source) {
        long totalBytesRead = 0L;

        @Override public long read(Buffer sink, long byteCount) throws IOException {
          long bytesRead = super.read(sink, byteCount);
          // read() returns the number of bytes read, or -1 if this source is exhausted.
          totalBytesRead += bytesRead != -1 ? bytesRead : 0;
          progressListener.update(totalBytesRead, responseBody.contentLength(), bytesRead == -1);
          return bytesRead;
        }
      };
    }
  }

  interface ProgressListener {
    void update(long bytesRead, long contentLength, boolean done);
  }
}

但是当我进行超过 9 个并行下载时，UI 显得很迟钝。所以我在监听器中下了一个断点，它说它属于主线程。

现在我想在后台线程中获取进度，稍后通过DataBinding更新它，那么我就不需要在主线程中处理source了。怎么做？谢谢。

Answer 1

您可以使用 CoreProgress框架，易于使用。