4.hql简单属性查询:测试

package com.bjpowernode.hibernate;

import java.text.SimpleDateFormat;
import java.util.Date;

import org.hibernate.Session;

public class InitData {

public static void main(String[] args) {
Session session = HibernateUtils.getSession();

try {
session.beginTransaction();

for(int i=0; i<10; i++){

Classes classes = new Classes();
classes.setName("班级"+i);
session.save(classes);

for(int j=0; j<10; j++){
Student student = new Student();
student.setName("班级"+i+"的学生"+j);
student.setCreateTime(randomDate("2009-07-01","2009-09-01"));

//在内存中建立由student指向classes的引用
student.setClasses(classes);
session.save(student);
}
}

for(int i=0; i<5; i++){
Classes classes = new Classes();
classes.setName("无学生班级"+i);
session.save(classes);
}

for(int i=0; i<10; i++){
Student student = new Student();
student.setName("无业游民"+i);
session.save(student);
}

session.getTransaction().commit();
} catch (Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
} finally{
HibernateUtils.closeSession(session);
}
}

/**
* 获取随机日期
* @param beginDate 起始日期，格式为：yyyy-MM-dd
* @param endDate 结束日期，格式为：yyyy-MM-dd
* @return
*/
private static Date randomDate(String beginDate,String endDate){
try {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
Date start = format.parse(beginDate);
Date end = format.parse(endDate);

if(start.getTime() >= end.getTime()){
return null;
}

long date = random(start.getTime(),end.getTime());

return new Date(date);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}

private static long random(long begin,long end){
long rtn = begin + (long)(Math.random() * (end - begin));
if(rtn == begin || rtn == end){
return random(begin,end);
}
return rtn;
}
}

package com.bjpowernode.hibernate;

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

import org.hibernate.Session;

import junit.framework.TestCase;

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

/**
* 单一属性查询
*/
@SuppressWarnings("unchecked")
public void testQuery1() {
Session session = null;
try {
session = HibernateUtils.getSession();
session.beginTransaction();
//返回结果集属性列表，元素类型和实体类中的属性类型一致
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);
}
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
}finally {
HibernateUtils.closeSession(session);
}
}

/**
* 多个属性查询
*/
@SuppressWarnings("unchecked")
public void testQuery2() {
Session session = null;
try {
session = HibernateUtils.getSession();
session.beginTransaction();
//查询多个属性，返回对象数组集合
//数组元素的类型与查询的属性类型一致
//数组的长度与select中查询的属性个数一致
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]);
}
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
}finally {
HibernateUtils.closeSession(session);
}
}

/**
* 多个属性查询,返回Student
*/
@SuppressWarnings("unchecked")
public void testQuery3() {
Session session = null;
try {
session = HibernateUtils.getSession();
session.beginTransaction();
//可以使用hql返回Student对象
//需要提供构造函数
List students = session.createQuery("select new Student(id, name) from Student").list();
for (Iterator iter=students.iterator(); iter.hasNext();) {
Student student = (Student)iter.next();
System.out.println(student.getId() + ", " + student.getName());
}
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
}finally {
HibernateUtils.closeSession(session);
}
}

/**
* 可以使用别名
*/
@SuppressWarnings("unchecked")
public void testQuery4() {
Session session = null;
try {
session = HibernateUtils.getSession();
session.beginTransaction();
// 可以使用别名
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]);
}
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
}finally {
HibernateUtils.closeSession(session);
}
}

/**
* 可以使用别名
*/
@SuppressWarnings("unchecked")
public void testQuery5() {
Session session = null;
try {
session = HibernateUtils.getSession();
session.beginTransaction();
// 可以采用as命名别名
List students = session.createQuery("select s.id, s.name from Student as s").list();
for (Iterator iter=students.iterator(); iter.hasNext();) {
Object[] obj = (Object[])iter.next();
System.out.println(obj[0] + ", " + obj[1]);
}
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
}finally {
HibernateUtils.closeSession(session);
}
}
}