android - 存储访问框架不更新 MediaScanner (MTP)

Question

使用 KitKat 中提供的 SAF，不会对保存到设备内部或外部存储点的文件调用 MediaScanner。因此，我必须根据返回的 URI 来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);
}

是否有其他人必须解决此问题？如果是，是否有比这更好的方法？目前只支持设备外接存储，SDCard等额外存储空间需要单独检查。

Answer 1

为了支持我认为是所有可能的安装，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，是否存在 4.4 平板电脑有全尺寸端口？)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;
            }
        }
    }
}