Criteria.uniqueResult()方法使查询持久性对象的单个实例变得更加容易。如果找不到持久性，则此方法将返回一个null值。
package org.nhooo.example.hibernate.criteria;
import org.hibernate.Criteria;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Restrictions;
import org.nhooo.example.hibernate.model.Genre;
public class UniqueResultExample {
public static Session getSession() throws HibernateException {
String cfg = "hibernate.cfg.xml";
SessionFactory sessionFactory = new Configuration().configure(cfg)
.buildSessionFactory();
return sessionFactory.openSession();
}
public static void main(String[] args) {
try (Session session = getSession()) {
Criteria criteria = session.createCriteria(Genre.class)
.add(Restrictions.eq("id", 1L));
//返回单个实例的便捷方法
//查询；如果查询未返回结果，则返回null。
Object result = criteria.uniqueResult();
if (result != null) {
Genre genre = (Genre) result;
System.out.println("Genre = " + genre.getName());
}
}
}
}
