android 扫描SD卡与系统文件

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<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
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;             }

转自：
http://blog.csdn.net/cai200711/article/details/6594985

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