还是参考前面的例子：http://blog.csdn.net/kunshan_shenbin/archive/2008/09/02/2864883.aspx
修改User.hbm.xml文件如下：
<!DOCTYPE hibernate-mapping PUBLIC
“-//Hibernate/Hibernate Mapping DTD 3.0//EN”
“http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd”>
<class name="com.hb3.pack_01.model.User" table="user"
dynamic-insert=”true”
dynamic-update=”true”
>
测试代码：
package com.hb3.pack_01;
import java.util.Iterator;
import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import com.hb3.pack_01.model.User;
public class BusinessService {
public static void main(String[] args) {
Configuration config = new Configuration().configure();
SessionFactory sessionFactory = config.buildSessionFactory();
Session session = sessionFactory.openSession();
Criteria criteria = session.createCriteria(User.class);
List users = criteria.list();
Iterator iterator = users.iterator();
System.out.println(“id /t name/age”);
while (iterator.hasNext()) {
User user = (User) iterator.next();
System.out.println(user.getId() + ” /t ” + user.getName() + “/” + user.getAge());
}
session.close();
System.out.println(“========================================”);
session = sessionFactory.openSession();
User user = new User();
user.setId(2);
user.setName(“chenyan”);
user.setAge(new Integer(24));
Transaction tx = session.beginTransaction();
session.saveOrUpdate(user);
tx.commit();
System.out.println(“========================================”);
user = new User();
user.setName(“yangye”);
user.setAge(new Integer(23));
tx = session.beginTransaction();
session.saveOrUpdate(user);
tx.commit();
System.out.println(“========================================”);
Query query = session.createQuery(“from User”);
users = query.list();
iterator = users.iterator();
System.out.println(“id /t name/age”);
while (iterator.hasNext()) {
user = (User) iterator.next();
System.out.println(user.getId() + ” /t ” + user.getName() + “/” + user.getAge());
}
session.close();
sessionFactory.close();
}
}
运行结果：
13:45:00,140 WARN ConfigurationFactory:127 – No configuration found. Configuring ehcache from ehcache-failsafe.xml found in the classpath: jar:file:/D:/Java/MyEclipse%206.0/workspace/hb3demo/ehcache-1.2.3.jar!/ehcache-failsafe.xml13:45:00,703 WARN EhCacheProvider:93 – Could not find configuration [org.hibernate.cache.UpdateTimestampsCache]; using defaults.13:45:00,734 WARN EhCacheProvider:93 – Could not find configuration [org.hibernate.cache.StandardQueryCache]; using defaults.Hibernate: select this_.id as id0_0_, this_.name as name0_0_, this_.age as age0_0_ from user this_id name/age1 shenbin/282 chenyan/25========================================Hibernate: update user set name=?, age=? where id=?========================================Hibernate: insert into user (name, age) values (?, ?)========================================Hibernate: select user0_.id as id0_, user0_.name as name0_, user0_.age as age0_ from user user0_id name/age1 shenbin/282 chenyan/243 yangye/23
提示：
unsaved-value可以设定的值包括：
any：总是存储
none：总是更新
null：id为null时存储（默认）
valid：id为null或是指定值时存储
值得一提的是：
正如上面的代码所示，使用查询语句查出对象后，不能使用同一个session直接对对象进行修改操作。否则会抛出异常：
Exception in thread “main” org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [com.hb3.pack_01.model.User#2]
……
当然这并不是saveOrUpdate方法独有的。save和update等方法使用不当也会出现如上异常。
解决方法可新建session, 或参阅：
http://www.blogjava.net/Unmi/archive/2007/08/10/135771.html
http://blog.csdn.net/tmpfree/archive/2006/03/13/623516.aspx
http://www.javaeye.com/topic/11581
一路走来，我们无法猜测将是迎接什么样的风景，
