Change username in spring security when logged in

Question

I want to change username while this user logged in system. I implemented my own crypt algorithm and cannot get real password to make a new authentication and put it in

Authentication authentication = new UsernamePasswordAuthenticationToken(principal, credentials);

Answer 1

After Logging in, you can change your username and password with this code:

Collection<SimpleGrantedAuthority> nowAuthorities = 
  (Collection<SimpleGrantedAuthority>)SecurityContextHolder.getContext()
                                                           .getAuthentication()
                                                           .getAuthorities();
UsernamePasswordAuthenticationToken authentication = 
  new UsernamePasswordAuthenticationToken(username, password, nowAuthorities);

SecurityContextHolder.getContext().setAuthentication(authentication);