通过 Retrofit 2 Asynchronous 下载时是否可以显示进度条？

Question

@Streaming
@GET
Call<ResponseBody> downloadSong(@Url String url);

以上代码用于通过改造异步下载文件。我想知道下载进度，如果有暂停/恢复的可能也请回答

Answer 1

我终于得到了答案。

为此，我们需要使用 rxjava 和改造。

下载ProgressListener.java

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

下载ProgressResponseBody.java

public class DownloadProgressResponseBody extends ResponseBody {

    private ResponseBody responseBody;
    private DownloadProgressListener progressListener;
    private BufferedSource bufferedSource;

    public DownloadProgressResponseBody(ResponseBody responseBody,
                                        DownloadProgressListener 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;

                if (null != progressListener) {
                    progressListener.update(totalBytesRead, responseBody.contentLength(), bytesRead == -1);
                }
                return bytesRead;
            }
        };

    }
}

下载ProgressInterceptor.java

public class DownloadProgressInterceptor implements Interceptor {

    private DownloadProgressListener listener;

    public DownloadProgressInterceptor(DownloadProgressListener listener) {
        this.listener = listener;
    }

    @Override
    public Response intercept(Chain chain) throws IOException {
        Response originalResponse = chain.proceed(chain.request());

        return originalResponse.newBuilder()
                .body(new DownloadProgressResponseBody(originalResponse.body(), listener))
                .build();
    }
}

下载.java

public class Download implements Parcelable {

    private int progress;
    private long currentFileSize;
    private long totalFileSize;

    public int getProgress() {
        return progress;
    }

    public void setProgress(int progress) {
        this.progress = progress;
    }

    public long getCurrentFileSize() {
        return currentFileSize;
    }

    public void setCurrentFileSize(long currentFileSize) {
        this.currentFileSize = currentFileSize;
    }

    public long getTotalFileSize() {
        return totalFileSize;
    }

    public void setTotalFileSize(long totalFileSize) {
        this.totalFileSize = totalFileSize;
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeInt(this.progress);
        dest.writeLong(this.currentFileSize);
        dest.writeLong(this.totalFileSize);
    }

    public Download() {
    }

    protected Download(Parcel in) {
        this.progress = in.readInt();
        this.currentFileSize = in.readLong();
        this.totalFileSize = in.readLong();
    }

    public static final Parcelable.Creator<Download> CREATOR = new Parcelable.Creator<Download>() {
        @Override
        public Download createFromParcel(Parcel source) {
            return new Download(source);
        }

        @Override
        public Download[] newArray(int size) {
            return new Download[size];
        }
    };
}

下载服务.java

public interface DownloadService {
    @Streaming
    @GET
    Observable<ResponseBody> download(@Url String url);
}

下载API.java

public class DownloadAPI {
    private static final String TAG = "DownloadAPI";
    private static final int DEFAULT_TIMEOUT = 15;
    public Retrofit retrofit;    

    public DownloadAPI(String url, DownloadProgressListener listener) {

        DownloadProgressInterceptor interceptor = new DownloadProgressInterceptor(listener);

        OkHttpClient client = new OkHttpClient.Builder()
                .addInterceptor(interceptor)
                .retryOnConnectionFailure(true)
                .connectTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS)
                .build();

        retrofit = new Retrofit.Builder()
                .baseUrl(url)
                .client(client)        
              .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .build();
    }

    public void downloadAPK(@NonNull String url, final File file, Subscriber subscriber) {
        Log.d(TAG, "downloadAPK: " + url);

        retrofit.create(DownloadService.class)
                    .download(url)
                    .subscribeOn(Schedulers.io())
                    .unsubscribeOn(Schedulers.io())
                    .map(new Func1<ResponseBody, InputStream>() {
                        @Override
                        public InputStream call(ResponseBody responseBody) {
                            return responseBody.byteStream();
                        }
                    })
                    .observeOn(Schedulers.computation())
                    .doOnNext(new Action1<InputStream>() {
                        @Override
                        public void call(InputStream inputStream) {
                            try {
                                FileUtils.writeFile(inputStream, file);
                            } catch (IOException e) {
                                e.printStackTrace();
                                throw new CustomizeException(e.getMessage(), e);
                            }
                        }
                    })
                    .observeOn(AndroidSchedulers.mainThread())
                    .subscribe(subscriber);
        }


    }

用法

DownloadProgressListener listener = new DownloadProgressListener() {
            @Override
            public void update(long bytesRead, long contentLength, boolean done) {
                Download download = new Download();
                download.setTotalFileSize(contentLength);
                download.setCurrentFileSize(bytesRead);
                int progress = (int) ((bytesRead * 100) / contentLength);
                download.setProgress(progress);

                sendNotification(download);
            }
        };
        File outputFile = new File(Environment.getExternalStoragePublicDirectory
                (Environment.DIRECTORY_DOWNLOADS), "file.apk");
        String baseUrl = StringUtils.getHostName(apkUrl);

        new DownloadAPI(baseUrl, listener).downloadAPK(apkUrl, outputFile, new Subscriber() {
            @Override
            public void onCompleted() {
                downloadCompleted();
            }

            @Override
            public void onError(Throwable e) {
                e.printStackTrace();
                downloadCompleted();
                Log.e(TAG, "onError: " + e.getMessage());
            }

            @Override
            public void onNext(Object o) {

            }
        });

Answer 2

我只是使用@Jan post的代码，但是遇到了无法下载并且只有一次回调的问题，经过多次尝试，我找到了解决方案：

OkHttpClient client = new OkHttpClient.Builder()
            // .addInterceptor(interceptor)
            .addNetworkInterceptor(interceptor)

只需将拦截器更改为 networkInterceptor 它运行正常！ 祝你好运！