title: File transfer without asking permission everytime
body: <p>I am developing an android app in which I want to send an image file between two devices very quickly. It's like the image will run from first to second, second to first and so on.
  The app will ask ONCE for the permission to use your Bluetooth (or if there is any other service to use) at the time app is started, but not at the times when the file is transferred.
  I searched for it and got to know that file transfer without permission, is not permitted in Android4+. so Is there any way i can achieve it?</p>
  
  <p>If it can be achieved with any other service than Bluetooth, I would like to know. Any suggestions will help. Thank you.</p>