问如何检测Android上是否正在运行新媒体文件扫描(后台)

EN

//end batch renaming operation
//start updating media store library
sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,Uri.parse("file://"+Environment.getExternalStorageDirectory()))); 
//show toast "updating"
op_media_mounted.show();
//catch when updaitng op ends
IntentFilter filter = new IntentFilter(Intent.ACTION_MEDIA_SCANNER_FINISHED);
filter.addDataScheme("file");                   
BroadcastReceiver mReceiver = (new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(Intent.ACTION_MEDIA_SCANNER_FINISHED)) {
        Toast.makeText(frm_elabora.this, "Scan complete.", Toast.LENGTH_SHORT).show();
                        }
                    }
                });
registerReceiver(mReceiver, filter);   

Button btnstart = (Button)findViewById(R.id.btn_start);
btnstart.setOnClickListener(new View.OnClickListener() {
    public void onClick(View view) {
        if ( there_isnt_scan_for_new_media_file )
            startActivity(intent_processing);
        else{
                wait_until_ACTION_MEDIA_SCANNER_FINISHED
                startActivity(intent_processing);
        }

    public static Uri getMediaScannerUri ()
    Since: API Level 1
    Uri for querying the state of the media scanner.

    //send broadcast
    sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, 
            Uri.parse("file://" +
            Environment.getExternalStorageDirectory())));
    //show media scanner state
    Toast.makeText(frm_elabora.this,
        MediaStore.getMediaScannerUri().toString(),
        Toast.LENGTH_SHORT).show();