Starting with a simple entity UserAccount If you create an interface for a repository like below then Spring Data will create a proxy for you to inject into your service. It will automatically give you save, find, findAll, findOne, count methods for free (ie you don't have to do any implementation code). Since the UserAccount entity has a usern…

JpaRepository Example

//JPA enitiy called UserAccount
@Entity
public class UserAccount {
@Id 
private Long id;
private String username;
......
}


// create an interface that Spring Data will use to create a proxy
public interface UserAccountRepository extends JpaRepository<UserAccount, Long> {
    public UserAccount findByUsername(String username);
}

// now in my service class
@Service("userAccountService")
public class UserAccountServiceImpl implements UserAccountService {

    @Inject
    private UserAccountRepository userRepos;

    public UserAccount  find(String username){
        return userRepos.findByName(userName);
    }
      


}