基於Android掃描sd卡與系統檔案的介紹

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。 複製代碼 代碼如下:12-13 15:39:11.062: VERBOSE/MediaPlayerService(67): Create new media retriever from pid 349<BR>
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<BR>
12-13 15:39:11.142: DEBUG/MediaScanner(349): prescan time: 44ms<BR>
12-13 15:39:11.142: DEBUG/MediaScanner(349): scan time: 13ms<BR>
12-13 15:39:11.142: DEBUG/MediaScanner(349): postscan time: 2ms<BR>
12-13 15:39:11.142: DEBUG/MediaScanner(349): total time: 59ms<BR>
12-13 15:39:11.152: DEBUG/MediaProvider(349): un-lock thumbnail worker<BR>
12-13 15:39:11.152: DEBUG/MediaProvider(349): un-lock thumbnail worker<BR>
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)？ 複製代碼 代碼如下:Cursor cursor = context.getContentResolver().query(<BR> MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,<BR> new String[] { MediaStore.Audio.Media._ID, MediaStore.Audio.Media.DISPLAY_NAME, MediaStore.Audio.Media.TITLE,<BR> MediaStore.Audio.Media.DURATION, MediaStore.Audio.Media.ARTIST, MediaStore.Audio.Media.ALBUM,<BR> MediaStore.Audio.Media.YEAR, MediaStore.Audio.Media.MIME_TYPE, MediaStore.Audio.Media.SIZE, MediaStore.Audio.Media.DATA}<BR> , "_size>?", new String[]{1024*1024+""},null);

好了，最後一個問題<BR> 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： 複製代碼 代碼如下: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;
}