android 扫描SD卡与系统文件（转）

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