Java 使用下载管理器下载时显示进度条

我使用下载管理器api下载大文件，我也实现了。但问题是，下载进度的通知显示在状态栏中。但是我想使用进度条在活动中显示通知。有人做过吗？如果有，请帮帮我

public class DownloadManagerActivity extends Activity {
private long enqueue;
private DownloadManager dm;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {
                long downloadId = intent.getLongExtra(
                        DownloadManager.EXTRA_DOWNLOAD_ID, 0);
                Query query = new Query();
                query.setFilterById(enqueue);
                Cursor c = dm.query(query);
                if (c.moveToFirst()) {
                    int columnIndex = c
                            .getColumnIndex(DownloadManager.COLUMN_STATUS);
                    if (DownloadManager.STATUS_SUCCESSFUL == c
                            .getInt(columnIndex)) {

                        ImageView view = (ImageView) findViewById(R.id.imageView1);
                        String uriString = c
                                .getString(c
                                        .getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));
                        view.setImageURI(Uri.parse(uriString));
                    }
                }
            }
        }
    };

    registerReceiver(receiver, new IntentFilter(
            DownloadManager.ACTION_DOWNLOAD_COMPLETE));
}

public void onClick(View view) {
    dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
    Request request = new Request(
            Uri.parse("http://www.vogella.de/img/lars/LarsVogelArticle7.png"));
    enqueue = dm.enqueue(request);

}

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这是我用来在活动中显示进度条的代码，下载是由下载管理器请求的

final ProgressDialog progressBarDialog= new ProgressDialog(this);
progressBarDialog.setTitle("Download App Data, Please Wait");

              progressBarDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            progressBarDialog.setButton(DialogInterface.BUTTON_POSITIVE, "OK",new DialogInterface.OnClickListener(){
                public void onClick(DialogInterface dialog,
                    int whichButton){
                    // Toast.makeText(getBaseContext(),
                    //       "OK clicked!", Toast.LENGTH_SHORT).show();
                }
            });
            progressBarDialog.setProgress(0);

            new Thread(new Runnable() {

                @Override
                public void run() {

                    boolean downloading = true;

                    DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
                    while (downloading) {

                        DownloadManager.Query q = new DownloadManager.Query();
                        q.setFilterById(DownloadManagerId); //filter by id which you have receieved when reqesting download from download manager
                        Cursor cursor = manager.query(q);
                        cursor.moveToFirst();
                        int bytes_downloaded = cursor.getInt(cursor
                            .getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR));
                        int bytes_total = cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES));

                        if (cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_STATUS)) == DownloadManager.STATUS_SUCCESSFUL) {
                            downloading = false;
                }

                final int dl_progress = (int) ((bytes_downloaded * 100l) / bytes_total);

                runOnUiThread(new Runnable() {

                    @Override
                    public void run() {

                        progressBarDialog.setProgress((int) dl_progress);

                    }
                });

                // Log.d(Constants.MAIN_VIEW_ACTIVITY, statusMessage(cursor));
                cursor.close();
            }

        }
    }).start();


  //show the dialog
        progressBarDialog.show();

          }

               }

我知道现在回答晚了。 但对于那些未来会带着同样疑问来的人

我想nkalra0123给出的方法可能不安全。 有一种叫做FileObserver的东西

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上述链接有更好的解决方案。

您可以在onClick中激活进度条。并在接收时解雇他。我如何显示进度条的进度。你能发布一些代码吗，这样我就能有一个清晰的想法。Thanx Previous:）可能重复感谢，但显然给定的解决方案在棉花糖之后停止工作。当文件非常大时，nkarla的解决方案在Api 27上工作正常，但在Api 29上工作不正常（例如，50 MB可以，但300 MB不行）。