title: Token authentication with Volley
body: <p>If I have a server where I authenticate with username/password and get auth token for subsequent requests, what would be the best approach addressing this problem?</p>
  
  <p>The flow should be like this:
  - Start request
  - If we don't have auth token - get it with username and password
  - Make request with auth token
  - If request failed because token expired, get new auth token with user name and password
  - Retry request with new auth token
  - Finish</p>
  
  <p>I've noticed that Volley already might have something that might solve this issue - Authenticator <a href="https://android.googlesource.com/platform/frameworks/support/+/4474bc11f64b2b274ca6db5a1e23e8c1d143d5fa/volley/src/com/android/volley/toolbox/Authenticator.java">https://android.googlesource.com/platform/frameworks/support/+/4474bc11f64b2b274ca6db5a1e23e8c1d143d5fa/volley/src/com/android/volley/toolbox/Authenticator.java</a> It contains getAuthToken() and invalidateAuthToken() methods which would be exactly what I want. But it seems that it's never used in the library at all.</p>