关于org.hibernate.NonUniqueObjectException

具体异常说明:
org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session:

解决方案:
在多次检索过程中,共用一个Session对象


示例:
-----------------------------
/**
	 * <p>
	 * 更改指定用户的角色
	 * </p>
	 * 
	 * @author chenwei
	 * @param eid:用户ID
	 * @param roleids:角色ID数组
	 * 
	 */
	public static void opeRolesOfEmp(Integer eid, String[] roleids)
			throws HibernateMsgException {
		org.hibernate.Session session = null;
		org.hibernate.Transaction tran = null;
		try {
			session = com.supersit.hibernate.factory.HibernateSessionFactory
					.getSession();
			tran = session.beginTransaction();
			Employee emp = (Employee) session.load(Employee.class, eid);
			java.util.Set roles = new java.util.HashSet();
			for (int i = 0; i < roleids.length; i++) {
				//查询角色(此处应传入一个Session对象,否则会抛出org.hibernate.NonUniqueObjectException)
				Role role = new RoleDao().getRoleById(session,new Integer(roleids[i]));
				System.out.println("rolename=" + role.getRolename());
				roles.add(role);
			}
			emp.setRoles(roles);
			session.saveOrUpdate(emp);
			tran.commit();
		} catch (Exception e) {
			e.printStackTrace();
			com.supersit.hibernate.factory.HibernateSessionFactory
					.rollbackTran(tran);
		} finally {
			com.supersit.hibernate.factory.HibernateSessionFactory
					.closeSession(session);
		}
	}




/**
	 * <p>
	 * 根据角色ID查找角色(传入一个Session对象)
	 * </p>
	 * 
	 * @param roleid:角色ID
	 * @return com.supersit.hibernate.bean.Role
	 * @throws HibernateMsgException
	 */
	public com.supersit.hibernate.bean.Role getRoleById(Session session,
			Integer roleid) throws HibernateMsgException {
		Role role = new Role();
		try {
			java.util.List list = session.createQuery(
					"from Role r where r.roleid=:id").setInteger("id", roleid)
					.list();
			if (list != null && list.size() > 0)
				role = (Role) list.get(0);

		} catch (Exception e) {

		}
		return role;
	}




/**
	 * <p>
	 * 根据角色ID查找角色(创建一个新的Session)
	 * </p>
	 * 
	 * @param roleid:角色ID
	 * @return com.supersit.hibernate.bean.Role
	 * @throws HibernateMsgException
	 */
	public com.supersit.hibernate.bean.Role getRoleById(Integer roleid)
			throws HibernateMsgException {
		Role role = new Role();
		Session session = null;
		Transaction tran = null;
		try {
			session = com.supersit.hibernate.factory.HibernateSessionFactory
					.getSession();
			tran = session.beginTransaction();
			java.util.List list = session.createQuery(
					"from Role r where r.roleid=:id").setInteger("id", roleid)
					.list();
			if (list != null && list.size() > 0)
				role = (Role) list.get(0);
			tran.commit();
		} catch (Exception e) {
			com.supersit.hibernate.factory.HibernateSessionFactory
					.rollbackTran(tran);
		} finally {
			com.supersit.hibernate.factory.HibernateSessionFactory
					.closeSession(session);
		}
		return role;
	}