Spring security cache User object when working with JWT.

SomeClass.java

// Jwt requires an authentication on every request.Assuming that you are storing your User objects in a relational database like MySQL,
// and that your API gets moderate traffic,it is not a good idea to fetch the User object directly from the database every time.
//Instead,once it is retreived ,we cache it locally using Spring Caching abstraction.The cache backend is Google guava.

public class UserServiceImpl implements UserService { //Which further extends UserDetailsService .

  @Override
	@Cacheable(cacheNames=CacheConstants.USER_CACHE,key="#username") // We cache this  guy by its username.
	public UserDetails loadUserByUsername(final String username) throws UsernameNotFoundException {
  		final User user = userRepository.findOneByEmail(username);
  		if(user==null){
  			throw new UsernameNotFoundException("User with username " + username + " not found");
  		}
  		return user;
	}
}
//This is the cache used.
public class CacheConfig{
    @Bean(name="localGauvaCaches")
  	public SimpleCacheManager localGuavaCaches(){
  		final SimpleCacheManager simpleCacheManager = new SimpleCacheManager();
  		final GuavaCache userCache = new GuavaCache(CacheConstants.USER_CACHE,CacheBuilder.newBuilder()
  												  .concurrencyLevel(3) //Choose per your own will.
  												  .expireAfterAccess(2, TimeUnit.MINUTES) //Expire if not accessed within 2 minutes.
  									 			  .maximumSize(1000).build()); //For a maximum of 1000 User Objects.

  		simpleCacheManager.setCaches(Arrays.asList(userCache));
  		
  		return simpleCacheManager;
  	}
  
  
}