توی فرگمنت صفحه هامو ساختم و زمانی که play کلیک میشه گفتم اگر فایل موجوده بخون اگرنه دانلود کن

     public void play(View view) {
        position = myPager.getCurrentItem();
        if (new File(G.DIR_FINAL + "/" + mAudio[position]).exists()) {
            mp = MediaPlayer.create(G.context, Uri.parse(G.DIR_FINAL + "/" + mAudio[position]));
            Toast.makeText(G.context, R.string.playing, Toast.LENGTH_LONG).show();

            if (mp != null && !mp.isPlaying()) {
                mp.start();
                finalTime = mp.getDuration();
                startTime = mp.getCurrentPosition();
                if (oneTimeOnly == 0) {
                    seekbar.setMax((int) finalTime);
                    oneTimeOnly = 1;

                }
                endTimeField.setText(String.format("%d min, %d sec",
                        TimeUnit.MILLISECONDS.toSeconds((long) finalTime) / 60,
                        TimeUnit.MILLISECONDS.toSeconds((long) finalTime) % 60)
                        );
                startTimeField.setText(String.format("%d min, %d sec",
                        TimeUnit.MILLISECONDS.toSeconds((long) startTime) / 60,
                        TimeUnit.MILLISECONDS.toSeconds((long) startTime) % 60)
                        );
                seekbar.setProgress((int) startTime);
                myHandler.postDelayed(UpdateSongTime, 100);
                pauseButton.setEnabled(true);
                playButton.setEnabled(false);
            }
        }
        else {
            filename = mAudio[myPager.getCurrentItem()];
            d = new AlertDialog.Builder(this)
                    .setTitle(R.string.download)
                    .setMessage(R.string.message)
                    .setPositiveButton(R.string.yes, new DialogInterface.OnClickListener() {

                        @Override
                        public void onClick(DialogInterface arg0, int arg1) {

                            Toast.makeText(G.context, R.string.downloading, Toast.LENGTH_LONG).show();
                            rlPrg.setVisibility(View.VISIBLE);
                            playButton.setEnabled(false);
                            seekbar.setVisibility(View.GONE);

                            Thread thread = new Thread(new Runnable() {

                                @Override
                                public void run() {
                                    startDownload("آدرس پوشه حاوی موزیک ها در سرور/" + filename, G.DIR_FINAL + "/" + filename, prgDownloadProgress, txtPercent);
                                }
                            });
                            thread.start();
                        }

                    })
                    .setNegativeButton(R.string.no, new DialogInterface.OnClickListener() {

                        public void onClick(DialogInterface dialog, int which) {

                        }
                    })

                    .setIcon(R.drawable.download)
                    .show();

            Resources res = G.context.getResources();
            TextView messageView = (TextView) ((Dialog) d).findViewById(android.R.id.message);
            messageView.setTextColor(res.getColor(R.color.white));
            final int titleId = res.getIdentifier("alertTitle", "id", "android");
            final View title = ((Dialog) d).findViewById(titleId);
            if (title != null) {
                ((TextView) title).setTextColor(res.getColor(R.color.white));
            }
            final int titleDividerId = res.getIdentifier("titleDivider", "id", "android");
            final View titleDivider = ((Dialog) d).findViewById(titleDividerId);
            if (titleDivider != null) {
                titleDivider.setBackgroundColor(res.getColor(R.color.white));
            }

        }
    }


    private void startDownload(final String downloadURL, final String filePath
                               , final ProgressBar prgDownloadProgress
                               , final TextView txtPercent) {
        ModuleDownloader downloadRequest = new ModuleDownloader();
        OnProgressDownloadListener progressListener = new OnProgressDownloadListener() {

            @Override
            public void onProgressDownload(final int percent, final int downloadedSize, final int fileSize) {

                G.HANDLER.post(new Runnable() {

                    @Override
                    public void run() {
                        Drawable draw = getResources().getDrawable(R.drawable.costum_progress);
                        prgDownloadProgress.setProgressDrawable(draw);
                        prgDownloadProgress.setProgress(percent);
                        txtPercent.setText(percent + " % ");
                    }
                });
            }
        };
        OnDownloadCompleteListener completeListener = new OnDownloadCompleteListener() {

            @Override
            public void OnDownloadComplete(final String filepath) {
                G.HANDLER.post(new Runnable() {

                    @Override
                    public void run() {
                        rlPrg.setVisibility(View.GONE);
                        pauseButton.setEnabled(false);
                        playButton.setEnabled(true);
                        seekbar.setVisibility(View.VISIBLE);
                        play(playButton);
                    }
                });
            }

        };
        downloadRequest.downloadPath(downloadURL)
                .filepath(filePath)
                .simulate(true)
                .progressListener(progressListener)
                .completeListener(completeListener);
        downloadRequest.download();
    }

متاسفانه خیلی تمیز نیست .ببخشید .ببینید مشکلتونو حل میکنه؟