Hibernate HQL示例三:属性查询

根据属性查询:

 单个属性查询，返回的结果集属性的列表，其元素和属性的类型一致
 多个属性查询,返回的结果集是数组类型，数组的长度和查询的属性数量相关，数组中元素的类型与相应的属性类型相同

 

示例

package com.bjsxt.hibernate;

import java.util.Iterator;
import java.util.List;

import org.hibernate.Session;

import junit.framework.TestCase;

/**
 * 简单的属性查询
 * @author Administrator
 *
 */
public class SimplePropertyQueryTest extends TestCase {

	/**
	 * 单一属性查询
	 *
	 */
	public void testQuery1() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			
			List students = session.createQuery("select name from Student").list();
			for (Iterator iter = students.iterator();iter.hasNext();) {
				String name = (String)iter.next();
				System.out.println(name);
			}
		}catch(Exception e) {
			e.printStackTrace();
		}finally {
			HibernateUtils.closeSession(session);
		}			
	}
	
	/**
	 * 多个属性的查询
	 *
	 */
	public void testQuery2() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			
			//查询多个属性，其集合元素是对象数组
			//数组元素的类型，跟实体类的属性的类型相关
			List students = session.createQuery("select id, name from Student").list();
			for (Iterator iter = students.iterator();iter.hasNext();) {
				Object[] obj = (Object[])iter.next();
				System.out.println(obj[0] + ", " + obj[1]);
			}
		}catch(Exception e) {
			e.printStackTrace();
		}finally {
			HibernateUtils.closeSession(session);
		}			
	}

	public void testQuery3() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			
			//查询多个属性，其集合元素是对象数组
			//数组元素的类型，跟实体类的属性的类型相关
			//更参见的用法，给对象起个别名，然后通过别名来引用属性值
			List students = session.createQuery("select s.id, s.name from Student s").list();
			for (Iterator iter = students.iterator();iter.hasNext();) {
				Object[] obj = (Object[])iter.next();
				System.out.println(obj[0] + ", " + obj[1]);
			}
		}catch(Exception e) {
			e.printStackTrace();
		}finally {
			HibernateUtils.closeSession(session);
		}			
	}
	
}