UserDao.java

package dao;

import javax.persistence.EntityManager;
import javax.persistence.Query;

import models.User;

import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.persist.Transactional;

public class UserDao {
    
    @Inject
    Provider<EntityManager> entityManagerProvider;
    
    @Transactional
    public boolean isUserAndPasswordValid(String username, String password) {
        
        if (username != null && password != null) {
            try {
                EntityManager entityManager = entityManagerProvider.get();
                Query q = entityManager.createQuery("SELECT x FROM User x WHERE username = :usernameParam");
                User user = (User) q.setParameter("usernameParam", username).getSingleResult();
                if (user.password.equals(password)) {
                    return true;
                }
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
        
        return false;
 
    }

}