在運行時授予WRITE_EXTERNAL_STORAGE權限時，應用程序無法訪問SD卡

Question

在android M中訪問sdcard必須在運行時授予權限時強制停止並啟動app，如何以編程方式實現？

但是，如果應用程序強制停止並重新啟動，則可以訪問sdcard。

AndroidManifest.xml：

uses-permission-sdk-m android:name="android.permission.WRITE_EXTERNAL_STORAGE


     /* **Checking permission **
        if doesn't have request
         else
         browse file directory       
    */

    String[] perm = { Manifest.permission.WRITE_EXTERNAL_STORAGE };
    if (checkSelfPermission(perm[0]) == PackageManager.PERMISSION_DENIED) {


                    requestPermissions(perm, REQ);

                } else {

                    Explore(); //method to browse file directory
                }

onRequestPermissionsResult

   @Override
public void onRequestPermissionsResult(int requestCode,
        String[] permissions, int[] grantResults) {
    // TODO Auto-generated method stub

    if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {  

   //Not able to browse SD card until restart application


       Explore(); //method to browse file directory


    } else {
        Log.i("onRequestPermissionsResult", " Request denied");
    }

    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}

Answer 1

您需要重新啟動應用程序才能獲得WRITE_EXTERNAL_STORAGE權限（其他一些權限）。 這是因為此權限實際上是Linux權限。 在這種情況下，Android的最新預覽版本不會重新啟動應用程序，但Google可能會在稍后添加。

您可以使用此代碼重新啟動：

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    // Write external store permission requires a restart
    for (int i = 0; i < permissions.length; i++)
        if (Manifest.permission.WRITE_EXTERNAL_STORAGE.equals(permissions[i]) &&
                grantResults[i] == PackageManager.PERMISSION_GRANTED) {
            Log.i(TAG, "Restarting application");

            // Schedule start after 1 second
            PendingIntent pi = PendingIntent.getActivity(
                    this,
                    0,
                    getIntent(),
                    PendingIntent.FLAG_CANCEL_CURRENT);
            AlarmManager am = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
            am.set(AlarmManager.RTC, System.currentTimeMillis() + 1000, pi);

            // Stop now
            System.exit(0);
        }
}

編輯：您可以在此處找到與Linux權限相關聯的Android權限列表： https ： //android.googlesource.com/platform/frameworks/base/+/master/data/etc/platform.xml

Answer 2

您可以在以下條件下檢查SD卡是否可用

if (android.os.Environment.getExternalStorageState().equals(
        android.os.Environment.MEDIA_MOUNTED)) {

 //Check for the file
 File appFolder = new File(Environment.getExternalStorageDirectory() + File.separator
            + context.getString(R.string.app_name));

 boolean exist = appFolder.exists();
}