Storing Authentication Token at application level which expires after certain time interval in spring -

i have spring rest application. application, giving call few rest apis. these apis need authentication token , there service call latest token. authentication token valid few hours , again expires , fresh token provided. need store token in memory , use calling apis. if tokenexpiredexception, giving call token generating method , retrieve new token , store in memory again use. please suggest best place store token can have readily available number of user.