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。

`1`	`12-13` `15:39:11.062: VERBOSE/MediaPlayerService(67): Create` `new` `media retriever from pid` `349<BR>`

`1`	`12-13` `15:39:11.082: DEBUG/MediaScannerService(349): getDefaultLocale =zh_CN`

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

`1`	`12-13` `15:39:11.142: INFO/MediaScanner(349): mOriginalCount =` `14, prune thumb flag =` `false<BR>`

`1`	`12-13` `15:39:11.142: DEBUG/MediaScanner(349): prescan time: 44ms<BR>`

`1`	`12-13` `15:39:11.142: DEBUG/MediaScanner(349): scan time: 13ms<BR>`

`1`	`12-13` `15:39:11.142: DEBUG/MediaScanner(349): postscan time: 2ms<BR>`

`1`	`12-13` `15:39:11.142: DEBUG/MediaScanner(349): total time: 59ms<BR>`

`1`	`12-13` `15:39:11.152: DEBUG/MediaProvider(349): un-lock thumbnail worker<BR>`

`1`	`12-13` `15:39:11.152: DEBUG/MediaProvider(349): un-lock thumbnail worker<BR>`

`1`	`12-13` `15:39:11.182: DEBUG/MediaScannerService(349): done scanning volume external`

`1`	`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`

`1`	`它存了些什么信息呢，拉出来看看吧：`

`1`	`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)？`

1 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);

`1`	`好了，最后一个问题<BR>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：`

`01`	`IntentFilter intentFilter =` `new` `IntentFilter(Intent.ACTION_MEDIA_SCANNER_STARTED);`

`02`	`intentFilter.addAction(Intent.ACTION_MEDIA_SCANNER_FINISHED);`

`03`	`intentFilter.addDataScheme("file");`

`04`	`scanReceiver =` `new` `ScanSdFilesReceiver();`

`05`	`registerReceiver(scanReceiver, intentFilter);`

`06`	`sendBroadcast(new` `Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://"` `+ Environment.getExternalStorageDirectory())));`

07

08

`09`	`private` `class` `ScanSdFilesReceiver` `extends` `BroadcastReceiver {`

`10`	`public` `void` `onReceive(Context context, Intent intent) {`

`11`	`String action = intent.getAction();`

`12`	`if` `(Intent.ACTION_MEDIA_SCANNER_STARTED.equals(action)) {`

`13`	`scanHandler.sendEmptyMessage(STARTED);`

14 }

`15`	`if` `(Intent.ACTION_MEDIA_SCANNER_FINISHED.equals(action)) {`

`16`	`scanHandler.sendEmptyMessage(FINISHED);`

17 }

18 }

19 }

20

21

`22`	`private` `Handler scanHandler =` `new` `Handler() {`

`23`	`public` `void` `handleMessage(Message msg) {`

`24`	`super.handleMessage(msg);`

`25`	`switch` `(msg.what) {`

`26`	`case` `STARTED:`

`27`	`MyDialog scanDialog =` `new` `MyDialog(LocalList.this);`

`28`	`scanAlertDialog = scanDialog.scanFile();`

`29`	`scanAlertDialog.show();`

`30`	`Log.i(TAG,` `"showing");`

31 break;

`32`	`case` `FINISHED:`

`33`	`ArrayList<Song> tempSongs = ReadFileList.readDataFromSD(LocalList.this, LOCAL);`

`34`	`if` `(tempSongs !=` `null` `&& tempSongs.size()>0) {`

`35`	`if` `(songs !=` `null` `&& songs.size()>0) {`

`36`	`songs.clear();`

`37`	`songs.addAll(tempSongs);`

`38`	`songAdapter.notifyDataSetChanged();`

`39`	`}else` `{`

`40`	`songs =` `new` `ArrayList<Song>();`

`41`	`songs.addAll(tempSongs);`

`42`	`initSong_lv();`

43 }

`44`	`}else` `{`

`45`	`Toast.makeText(LocalList.this,` `"SD卡中没有歌曲，请添加后再扫描", Toast.LENGTH_SHORT).show();`

46 }

`47`	`Log.i(TAG,` `"finish");`

`48`	`if` `(scanAlertDialog!=null` `&& scanAlertDialog.isShowing()) {`

`49`	`scanAlertDialog.dismiss();`

50 }

`51`	`unregisterReceiver(scanReceiver);`

52 break;

`53`	`case` `DISMISS:`

`54`	`Log.i(TAG,` `"dismiss");`

`55`	`if` `(scanAlertDialog!=null` `&& scanAlertDialog.isShowing()) {`

`56`	`scanAlertDialog.dismiss();`

57 }

`58`	`default:`

59 break;

60 }

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