android - 如何在 Oreo 中创建下载进度通知？

Question

我正在创建一个可以从服务器下载文件并在状态栏中显示进度的应用程序。这是我的代码:

private void startDownload(final String fileUrl) {
    Thread thread = new Thread() {
        @Override
        public void run() {
            NotificationManagerCompat notificationManagerCompat = NotificationManagerCompat.from(DownloadsActivity.this);

            String contentTitle = "Start downloading";
            Intent notifyIntent = new Intent();
            PendingIntent notifyPendingIntent = PendingIntent.getActivity(DownloadsActivity.this, DOWNLOAD_NOTIFICATION_ID, notifyIntent, PendingIntent.FLAG_UPDATE_CURRENT);

            NotificationCompat.Builder notificationBuilder = createNotificationBuilder("downloader_channel");
            notificationBuilder.setContentIntent(notifyPendingIntent);
            notificationBuilder.setTicker("Start downloading from the server");
            notificationBuilder.setOngoing(true);
            notificationBuilder.setAutoCancel(false);
            notificationBuilder.setSmallIcon(android.R.drawable.stat_sys_download);
            notificationBuilder.setContentTitle(contentTitle);
            notificationBuilder.setContentText("0%");
            notificationBuilder.setProgress(100, 0, false);
            notificationManagerCompat.notify(DOWNLOAD_NOTIFICATION_ID, notificationBuilder.build());

            boolean success;
            try {
                String fileName = DownloadUtils.getInstance().getFullFileName(fileUrl);
                File tmpFile = new File(fileName + ".tmp");

                URL url = new URL(fileUrl);
                URLConnection conection = url.openConnection();
                conection.connect();
                int fileLength = conection.getContentLength();

                // input stream to read file - with 8k buffer
                InputStream input = new BufferedInputStream(url.openStream(), 8192);

                // Output stream to write file

                OutputStream output = new FileOutputStream(tmpFile);

                byte data[] = new byte[1024];

                long total = 0;
                int count, tmpPercentage = 0;
                while ((count = input.read(data)) != -1) {
                    total += count;
                    output.write(data, 0, count);
                    int percentage = (int) ((total * 100) / fileLength);
                    if (percentage > tmpPercentage) {
                        notificationBuilder.setContentText(percentage + "%");
                        notificationBuilder.setProgress(100, percentage, false);
                        notificationManagerCompat.notify(DOWNLOAD_NOTIFICATION_ID, notificationBuilder.build());
                        tmpPercentage = percentage;
                    }
                }

                // flushing output
                output.flush();

                // closing streams
                output.close();
                input.close();

                // rename file but cut off .tmp
                File newFile = new File(fileName);
                success = tmpFile.renameTo(newFile);
            } catch (Exception e) {
                showLog("[Download Error]: " + e.getMessage());
                success = false;
            }
            showLog("Download finished");
            contentTitle = "Downloaded";
            String statusText = success ? "Done" : "Fail";
            int resId = success ? android.R.drawable.stat_sys_download_done : android.R.drawable.stat_notify_error;
            notificationBuilder.setContentTitle(contentTitle);
            notificationBuilder.setSmallIcon(resId);
            notificationBuilder.setOngoing(false);
            notificationBuilder.setAutoCancel(true);
            notificationBuilder.setContentText(statusText);
            notificationBuilder.setProgress(0, 0, false);
            notificationManagerCompat.notify(DOWNLOAD_NOTIFICATION_ID, notificationBuilder.build());
            isDownloading = false;
        }
    };
    isDownloading = true;
    thread.start();
}

private NotificationCompat.Builder createNotificationBuilder(String channelId) {
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
        String channelName = getString(R.string.app_name);
        NotificationChannel notificationChannel = new NotificationChannel(channelId, channelName, NotificationManager.IMPORTANCE_DEFAULT);
        notificationChannel.setLightColor(Color.BLUE);
        notificationChannel.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
        NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        if (notificationManager != null) {
            notificationManager.createNotificationChannel(notificationChannel);
        }
    }
    return new NotificationCompat.Builder(this, channelId);
}

在下载过程中，它会正确显示进度，但它会在进度的每一百分比时发出通知声音。还有一个问题是下载完成后，它仍然显示进度，用户无法清除通知。

注意:它在旧版本上运行良好。仅在 Android 8 中发生。

Answer 1

我通过在创建通知 channel 时将 NotificationManager.IMPORTANCE_DEFAULT 更改为 NotificationManager.IMPORTANCE_LOW 解决了这个问题。