Intent.ACTION_MEDIA_SCANNER_SCAN_FILE：扫描指定文件

1．启动MediaScanner服务，扫描媒体文件：
程序通过发送下面的Intent启动MediaScanner服务扫描指定的文件或目录：

Intent.ACTION_MEDIA_SCANNER_SCAN_FILE：扫描指定文件

public void scanFileAsync(Context ctx, String filePath) {
              Intent scanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
              scanIntent.setData(Uri.fromFile(new File(filePath)));
              ctx.sendBroadcast(scanIntent);
       }

public static final String ACTION_MEDIA_SCANNER_SCAN_DIR = "android.intent.action.MEDIA_SCANNER_SCAN_DIR";
       public void scanDirAsync(Context ctx, String dir) {
              Intent scanIntent = new Intent(ACTION_MEDIA_SCANNER_SCAN_DIR);
              scanIntent.setData(Uri.fromFile(new File(dir)));
              ctx.sendBroadcast(scanIntent);
       }