OkHttpファイルのダウンロードとInterceptorによるダウンロードの進捗状況

public class ProgressDownLoadFile {

    private static final OkHttpClient client = new OkHttpClient();

    public static void main(String[] args) throws IOException {

        // 
        final ProgressListener progressListener = new ProgressListener() {
            @Override public void update(long bytesRead, long contentLength, boolean done) {
                System.out.format("%d%% done
", (100 * bytesRead) / contentLength);
            }
        };

        // ， ResponseBody， 
        client.networkInterceptors().add(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();

            }
        });

        // 
        Request request = new Request.Builder()
                // 
                .url("http://img.pconline.com.cn/images/upload/upc/tx/wallpaper/1308/15/c2/24494083_1376530583817.jpg")
                .build();


        // 
        client.newCall(request).enqueue(new Callback() {
            @Override public void onFailure(Request request, IOException e) {
                System.out.println("failure");
            }

            @Override public void onResponse(Response response) throws IOException {
                // ， 
                int len;
                byte[] buf = new byte[2048];
                InputStream inputStream = response.body().byteStream();
                // 
                File file1 = new File("d:\\file.jpg");
                FileOutputStream fileOutputStream = new FileOutputStream(file1);

                while ((len = inputStream.read(buf)) != -1) {
                    fileOutputStream.write(buf, 0, len);
                }

                fileOutputStream.flush();
                fileOutputStream.close();
                inputStream.close();
            }
        });
    }

    /** *  ResponseBody */
    private static class ProgressResponseBody extends ResponseBody {
        private final ResponseBody responseBody;
        private final ProgressListener progressListener;
        private BufferedSource bufferedSource;

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

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


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

        @Override public BufferedSource source() throws IOException {
            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);
                    totalBytesRead += bytesRead != -1 ? bytesRead : 0;
                    progressListener.update(totalBytesRead, responseBody.contentLength(), bytesRead == -1);
                    return bytesRead;
                }
            };
        }
    }


    interface ProgressListener {
        /** * @param bytesRead   * @param contentLength   * @param done   */
        void update(long bytesRead, long contentLength, boolean done);
    }
}