Android扫描ｓｄ卡和系统文件

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如果你做过多媒体应用，一定会苦恼过，怎样获取sd卡中的多媒体文件。android还是很强大的，如果你知道怎么调用android的api，万事就ok了。

 当手机或模拟器开机时，会调用android的MediaScanner，扫描sd卡和内存里的文件。以下是log信息。

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

那么扫描后的记录它保存到哪里了呢。哈。你觉得在哪里呢？data/data/com.android.media/providers/databases/external

它存了些什么信息呢，拉出来看看吧：

 那么，我们直接使用ContentProvider就可以直接获取到sd卡中多媒体的信息了，你还用去listfile么？还用去自己解析媒体文件中的信息么(时长，文件名，专辑名。。应有尽有哦)？

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，最后一个问题
 当你往sd卡中添加一些多媒体文件的时候，android没有自动将它刷新到数据库中。那么我们怎么让它手动刷新呢，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卡中没有歌曲，请添加后再扫描", 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;
			}