存储访问框架不更新MediaScanner（MTP）

Question

使用KitKat中提供的SAF，MediaScanner不会调用保存到设备内部或外部存储点的文件。因此，我必须根据返回的URI确定是否应该尝试运行MediaScanner。

// The SAF uses content URI to pass meta about the file. The following host is used for internal storage. 
if (mExportServiceUri.getHost().equals("com.android.externalstorage.documents")) { 
    final File externalStorage = Environment.getExternalStorageDirectory(); 
    final String path = mExportServiceUri.getEncodedPath().replace("/document/primary%3A", ""); 
    MediaScannerConnection.scanFile(mService.getApplicationContext(), new String[] { new File(
      externalStorage, path).getAbsolutePath() }, null, null); 
} 

有没有其他人必须解决这个问题，如果是的话，有没有比这更好的方法？目前这仅支持设备外部存储，并且额外的存储空间（如SD卡）需要在单独的支票中处理。

Answer 1

为了支持我认为所有可能的安装方式，包括通过OTG连接的USB拇指驱动器，甚至可能直接连接到某些平板电脑上的全尺寸USB端口（我没有平板电脑来测试它，存在一个全尺寸的端口？）我有以下似乎在Galaxy S4（Play商店版）和N5上运行良好。

// The SAF uses content URI to pass meta about the file. The following host is used for SD storage. 
if (mExportServiceUri.getHost().equals("com.android.externalstorage.documents")) { 
    final String encodedPath = mExportServiceUri.getEncodedPath(); 
    final String path = encodedPath.substring(encodedPath.indexOf("%3A") + 3); 
    final File[] storagePoints = new File("/storage").listFiles(); 

    // document/primary is in /storage/emulated/legacy and thus will fail the exists check in the else handling loop check 
    if (encodedPath.startsWith("/document/primary")) { 
     // External file stored in Environment path 
     final File externalFile = new File(Environment.getExternalStorageDirectory(), path); 
     MediaScannerConnection.scanFile(mService.getApplicationContext(), 
       new String[] { externalFile.getAbsolutePath() }, null, null); 
    } else { 
     // External file stored in one of the mount points, check each mount point for the file 
     for (int i = 0, j = storagePoints.length; i < j; ++i) { 
      final File externalFile = new File(storagePoints[i], path); 
      if (externalFile.exists()) { 
       MediaScannerConnection.scanFile(mService.getApplicationContext(), 
         new String[] { externalFile.getAbsolutePath() }, null, null); 
       break; 
      } 
     } 
    } 
}