Unable to save files in API 23 anymore - android-6.0-marshmallow

Question

We have an application which saves images in a directory in an SD card. The directory is created if it does not already exist.
Here is the code that has done the job before the arrival of API 23:
OutputStream output;
File filepath = Environment.getExternalStorageDirectory();
File dir = new File(filepath.getAbsolutePath()
+ "/fingerprint/");
dir.mkdirs();
Bitmap bitmap = m_bitmap;
File file = new File(dir, userId.getText().toString() + ".jpg");
try {
output = new FileOutputStream(file);
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, output);
output.flush();
output.close();
} catch (Exception e) {
e.printStackTrace();
}
For some reasons, the directory is no longer created and files are no longer saved in Android 6.0. We introduced these methods to update our code with API changes in Marshmallow.
private void requestPermission(final Context context){
if(ActivityCompat.shouldShowRequestPermissionRationale((Activity)context, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
new AlertDialog.Builder(context)
.setMessage(context.getResources().getString(R.string.permission_storage))
.setPositiveButton(R.string.allow, 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 {
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 REQUEST_WRITE_EXTERNAL_STORAGE: {
if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Toast.makeText(CaptureFingerprintActivity.this,
getResources().getString(R.string.permission_storage_success),
Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(CaptureFingerprintActivity.this,
getResources().getString(R.string.permission_storage_failure),
Toast.LENGTH_SHORT).show();
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
return;
}
}
}
And the code that creates the directory and saves files is also updated.
OutputStream output;
File storageDir = null;
if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {
if (PackageManager.PERMISSION_GRANTED == ActivityCompat.checkSelfPermission(CaptureFingerprintActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
storageDir = new File(Environment.Environment.getExternalStorageDirectory()
, "fingerprint");
if (!storageDir.exists()) {
storageDir.mkdir();
} else {
requestPermission(CaptureFingerprintActivity.this);
}
}
Bitmap bitmap = m_bitmap;
File file = new File(storageDir, userId.getText().toString() + ".jpg");
try {
output = new FileOutputStream(file);
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, output);
output.flush();
output.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
This still doesn't seem to be creating directories.