发布于 2016-04-16 10:28:05 | 121 次阅读 | 评论: 0 | 来源: 网友投递

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Android移动端操作系统

Android是一种基于Linux的自由及开放源代码的操作系统，主要使用于移动设备，如智能手机和平板电脑，由Google公司和开放手机联盟领导及开发。尚未有统一中文名称，中国大陆地区较多人使用“安卓”或“安致”。

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本篇文章是对Android扫描sd卡与系统文件进行了详细的分析介绍，需要的朋友参考下
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<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(<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：

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; 
            }