Android 6(M) permission issue (create directory no

问题:

I have this code for creating directory for saving pictures:

        File storageDir = null;
        if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {                
            storageDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "myphoto");
            if (!storageDir.mkdirs()) {                    
                if (!storageDir.exists()){                       
                    Log.d("photo", "failed to create directory");
                    return null;
                }
            }
        }
        return storageDir;

storeDir returns "/storage/emulated/0/Pictures/myphoto/" below android 6 and on android 6 it returns null.

I have permission <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

buildToolVersion 23 targetSdkVersion 23

How to fix?

回答1:

As @CommonsWare answered, there is run-time permission asking concept on Android M, so in new approach, permissions are not asked when installing the app but when trying to use specific feature of phone which requests permission, at run-time. User later can disable permission from phone settings->app->yourapp->permissions as well. So you have to check before doing something with that permission, and ask user:

int REQUEST_WRITE_EXTERNAL_STORAGE=1;
////...
        File storageDir = null;
        if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {
            //RUNTIME PERMISSION Android M
            if(PackageManager.PERMISSION_GRANTED==ActivityCompat.checkSelfPermission(context,Manifest.permission.WRITE_EXTERNAL_STORAGE)){
                storageDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "myPhoto");
            }else{
                requestPermission(context);
            }    

        } 
        return storageDir;
////...
        private static void requestPermission(final Context context){
        if(ActivityCompat.shouldShowRequestPermissionRationale((Activity)context,Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
            // Provide an additional rationale to the user if the permission was not granted
            // and the user would benefit from additional context for the use of the permission.
            // For example if the user has previously denied the permission.

            new AlertDialog.Builder(context)
                    .setMessage(context.getResources().getString(R.string.permission_storage))
                    .setPositiveButton(R.string.tamam, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    ActivityCompat.requestPermissions((Activity) context,
                            new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                            REQUEST_WRITE_EXTERNAL_STORAGE);
                }
            }).show();

        }else {
            // permission has not been granted yet. Request it directly.
            ActivityCompat.requestPermissions((Activity)context,
                    new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                    REQUEST_WRITE_EXTERNAL_STORAGE);
        }
    }

///...

    @Override
    public void onRequestPermissionsResult(int requestCode,String permissions[], int[] grantResults) {
        switch (requestCode) {
            case UtilityPhotoController.REQUEST_WRITE_EXTERNAL_STORAGE: {
                if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    Toast.makeText(context,
                            getResources().getString(R.string.permission_storage_success),
                            Toast.LENGTH_SHORT).show();

                } else {
                    Toast.makeText(context,
                            getResources().getString(R.string.permission_storage_failure),
                            Toast.LENGTH_SHORT).show();
                    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
                }
                return;
            }
        }
    }

回答2:

You are running this on an Android 6.0+ environment and you have a targetSdkVersion of 23.

In that case, WRITE_EXTERNAL_STORAGE is part of the Android 6.0 runtime permission system. Either revise your app to participate in this system, or drop your targetSdkVersion below 23.

回答3:

You must get permission for this work like:

for do it impliment this code:

 if (ContextCompat.checkSelfPermission(this,
            Manifest.permission.WRITE_EXTERNAL_STORAGE)
            != PackageManager.PERMISSION_GRANTED) {

        if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                Manifest.permission.WRITE_EXTERNAL_STORAGE)) {

        } else {


            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},23
                    );
        }
    }

good luck!!!

回答4:

Try this code.

@Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

             if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                            if (checkPermission()) {
                                //do your work
                            } else {
                                requestPermission();
                            }
                        }
               }


                protected boolean checkPermission() {
                    int result = ContextCompat.checkSelfPermission(this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE);
                    if (result == PackageManager.PERMISSION_GRANTED) {
                        return true;
                    } else {
                        return false;
                    }
                }

                protected void requestPermission() {

                    if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
                        Toast.makeText(this, "Write External Storage permission allows us to do store images. Please allow this permission in App Settings.", Toast.LENGTH_LONG).show();
                    } else {
                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                            requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 100);
                        }
                    }
                }

            @Override
            public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
                switch (requestCode) {
                    case 100:
                        if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                            //do your work
                        } else {
                            Log.e("value", "Permission Denied, You cannot use local drive .");
                        }
                        break;
                }
            }