CXF - WSS4INTERCEPTOR - USERNAME

[Marcello Ribeiro]

Is there any way to send username/password from client to server just 
once, using WSS4iNTERCEPTOR? Only during the first login?
I think about keeping a token and using it all next times instead of 
storing username/password to be sent every logins.

In case of a mobile app running in Android as CXF WS client, would it be 
a good practice to store username/password to be used in the other logins?
I don´t think so, but at same time i am looking for solutions to avoid 
password being "hacked" directly in the device;

Att,
Marcello Ribeiro