Android掃描ｓｄ卡和系統檔案

原創作品，轉載請註明

如果你做過多媒體應用，一定會苦惱過，怎樣擷取sd卡中的多媒體檔案。android還是很強大的，如果你知道怎麼調用android的api，萬事就ok了。

 當手機或模擬器開機時，會調用android的MediaScanner，掃描sd卡和記憶體裡的檔案。以下是log資訊。

12-13 15:39:11.062: VERBOSE/MediaPlayerService(67): Create new media retriever from pid 349

12-13 15:39:11.082: DEBUG/MediaScannerService(349): getDefaultLocale =zh_CN

12-13 15:39:11.122: DEBUG/SurfaceFlinger(102): Layer::requestBuffer(this=0x7c8c68), index=1, pid=12866, w=309, h=192 success

12-13 15:39:11.142: INFO/MediaScanner(349): mOriginalCount = 14, prune thumb flag = false

12-13 15:39:11.142: DEBUG/MediaScanner(349):  prescan time: 44ms

12-13 15:39:11.142: DEBUG/MediaScanner(349):     scan time: 13ms

12-13 15:39:11.142: DEBUG/MediaScanner(349): postscan time: 2ms

12-13 15:39:11.142: DEBUG/MediaScanner(349):    total time: 59ms

12-13 15:39:11.152: DEBUG/MediaProvider(349): un-lock thumbnail worker

12-13 15:39:11.152: DEBUG/MediaProvider(349): un-lock thumbnail worker

12-13 15:39:11.182: DEBUG/MediaScannerService(349): done scanning volume external

那麼掃描後的記錄它儲存到哪裡了呢。哈。你覺得在哪裡呢？data/data/com.android.media/providers/databases/external

它存了些什麼資訊呢，拉出來看看吧：

 那麼，我們直接使用ContentProvider就可以直接擷取到sd卡中多媒體的資訊了，你還用去listfile嗎？還用去自己解析媒體檔案中的資訊麼(時間長度，檔案名稱，專輯名。。應有盡有哦)？

Cursor cursor = context.getContentResolver().query(
    MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
    new String[] { MediaStore.Audio.Media._ID, MediaStore.Audio.Media.DISPLAY_NAME, MediaStore.Audio.Media.TITLE,
      MediaStore.Audio.Media.DURATION, MediaStore.Audio.Media.ARTIST, MediaStore.Audio.Media.ALBUM,
      MediaStore.Audio.Media.YEAR, MediaStore.Audio.Media.MIME_TYPE, MediaStore.Audio.Media.SIZE, MediaStore.Audio.Media.DATA}
    , "_size>?", new String[]{1024*1024+""},null);

好了，最後一個問題
 當你往sd卡中添加一些多媒體檔案的時候，android沒有自動將它重新整理到資料庫中。那麼我們怎麼讓它手動重新整理呢，如下：

IntentFilter intentFilter = new IntentFilter(Intent.ACTION_MEDIA_SCANNER_STARTED);intentFilter.addAction(Intent.ACTION_MEDIA_SCANNER_FINISHED);intentFilter.addDataScheme("file");scanReceiver = new ScanSdFilesReceiver();registerReceiver(scanReceiver, intentFilter);sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + Environment.getExternalStorageDirectory())));private class ScanSdFilesReceiver extends BroadcastReceiver {public void onReceive(Context context, Intent intent) {String action = intent.getAction();if (Intent.ACTION_MEDIA_SCANNER_STARTED.equals(action)) {scanHandler.sendEmptyMessage(STARTED);}if (Intent.ACTION_MEDIA_SCANNER_FINISHED.equals(action)) {scanHandler.sendEmptyMessage(FINISHED);}}}private Handler scanHandler = new Handler() {public void handleMessage(Message msg) {super.handleMessage(msg);switch (msg.what) {case STARTED:MyDialog scanDialog = new MyDialog(LocalList.this);scanAlertDialog = scanDialog.scanFile();scanAlertDialog.show();Log.i(TAG, "showing");break;case FINISHED:ArrayList<Song> tempSongs = ReadFileList.readDataFromSD(LocalList.this, LOCAL);if (tempSongs != null && tempSongs.size()>0) {if (songs != null && songs.size()>0) {songs.clear();songs.addAll(tempSongs);songAdapter.notifyDataSetChanged();}else {songs = new ArrayList<Song>();songs.addAll(tempSongs);initSong_lv();}}else {Toast.makeText(LocalList.this, "SD卡中沒有歌曲，請添加後再掃描", Toast.LENGTH_SHORT).show();}Log.i(TAG, "finish");if (scanAlertDialog!=null && scanAlertDialog.isShowing()) {scanAlertDialog.dismiss();}unregisterReceiver(scanReceiver);break;case DISMISS:Log.i(TAG, "dismiss");if (scanAlertDialog!=null && scanAlertDialog.isShowing()) {scanAlertDialog.dismiss();}default:break;}