hql(二)
一：BaseDao的作用
1：为了解决赋值操作
2：分页 a:查询符合条件的总记录数
b:查询符合条件的某一页的记录数
二： 原生sql
hql实现不了的功能，可以考虑使用原生sql
1、多表（5+）联查
2、未配置映射文件中关系
原生态查询sql
String sql=“select b.book_name,o.order_no from t_hibernate_book b,t_hibernate_order o where 1=1”;
List list = session.createSQLQuery(sql).list();
三：视图映射
列如：
create view book_order
as
select b.book_name,o.order_no from t_hibernate_book b,t_hibernate_order o where 1=1
//创建视图
String sql=“select * from book_order”;
package com.zking.eight.dao;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import org.hibernate.Session;
import org.hibernate.query.Query;
import com.zking.five.entity.Book;
/**
* 作用：
* 1；将赋值的操作交给basedao
* 2:分页
* a:查询出符合条件的总记录数
* b:查询出符合某一页的记录数
*/
public class BaseDao {
/**
* 赋值操作
* @param query 预定义对象
* @param map 前台传过来的参数
*/
private void setParameter(Query query,Map map) {
//query.setParameter("bookName", "%"+book.getBookName()+"%");
//如果页面没有传值就直接返回 不赋值
if(map ==null &&map.size()==0) {
return;
}
Object value=null;
//有值就遍历
for (Map.Entry entry : map.entrySet()) {
//获取其值
value=entry.getValue();
if(value instanceof Collection) {//为所有的父类
query.setParameterList(entry.getKey(),(Collection) value);
}
else if(value instanceof Object[]) {//如果为数组
query.setParameterList(entry.getKey(), (Object[]) value);
}
else {//正常情况
query.setParameter(entry.getKey(), value);
}
}
}
/**
* 分页
* jdbc:
* sql=select * from t_hibernate_book where book_name like "%双世宠妃%"
* countSql=select count(*) from (select * from t_hibernate_book where book_name like "%双世宠妃%")
* pageSql=sql+"limt ?,?" hibernate中这一步被省略
*
* hql="from Book where bookName like '%双世宠妃%'"
*
* 思路：
* 只需要截取from 后的sql语句 前面拼接 select count(*) 就可获取总记录数
*
* 注意：from 可以有多种形式 所以要先转化为全大写
*
*/
public String getCountHql(String hql) {
//hql转为大写 获取FROM下标 获取临时的 所以 return 要转
int index = hql.toUpperCase().indexOf("FROM");
return hql.substring(index);
}
public List executeQuery(Session session,String hql,PageBean pageBean,Map map) {
//判断是否需要分页
if(pageBean !=null && pageBean.isPagination()) {
//1拿到分页的总记录数
//select count(*) from Book where bookName like '%双世宠妃%'
String countHql ="select count(*)"+ getCountHql(hql);
Query countQuery = session.createQuery(countHql);
this.setParameter(countQuery, map);
//pageBean设置总记录数 ，最后用于分页
String total = countQuery.getSingleResult().toString();
pageBean.setTotal(total);
//或者:pageBean.setTotal(countQuery.getSingleResult().toString());
//查询展示数据
Query pageQuery = session.createQuery(hql);
pageQuery.setFirstResult(pageBean.getStartIndex());
pageQuery.setMaxResults(pageBean.getRows());
this.setParameter(pageQuery, map);
return pageQuery.list();
}else {//不分页
//生成预定义对象
Query query = session.createQuery(hql);
this.setParameter(query, map);
return query.list();
}
}
}
package com.zking.eight.test;
import java.util.Arrays;
import java.util.List;
import org.junit.Test;
import com.zking.eight.dao.PageBean;
import com.zking.five.dao.BookDao;
import com.zking.five.entity.Book;
public class TestQuery {
private BookDao bookDao=new BookDao();
@Test
public void testList1() {
PageBean pageBean=new PageBean();
Book book=new Book();
//pageBean.setPage(2);
book.setBookName("双世宠妃");
List list1 = this.bookDao.list1(book, pageBean);
list1.forEach(System.out::println);
}
/**
* 通用分页
*/
@Test
public void testList2() {
PageBean pageBean=new PageBean();
Book book=new Book();
//pageBean.setPage(2);
book.setBookName("哈哈哈");
List list1 = this.bookDao.list2(book, pageBean);
list1.forEach(System.out::println);
}
@Test
public void testList3() {
PageBean pageBean=new PageBean();
Book book=new Book();
pageBean.setPage(2);
//book.setBookName("哈哈哈");
List list1 = this.bookDao.list3(book, pageBean);
for (Object[] b : list1) {
System.out.println(Arrays.toString(b));
}
}
}
//无BaseDao
public List list1(Book book,PageBean pageBean){
Session session = SessionFactoryUtil.getSession();
Transaction transaction = session.beginTransaction();
String hql="from Book where 1=1";
if(StringUtils.isNotBlank(book.getBookName())) {
hql+=" and bookName like :bookName";
}
Query query = session.createQuery(hql);
//如果没有传入name就不需要加入 每一个就必须判断 太麻烦 所有需要一个通用的
if(StringUtils.isNotBlank(book.getBookName())) {
query.setParameter("bookName", "%"+book.getBookName()+"%");
}
if(pageBean!=null&&pageBean.isPagination()) {
query.setFirstResult(pageBean.getStartIndex());
query.setMaxResults(pageBean.getRows());
}
List list = query.list();
transaction.commit();
session.close();
return list;
}
public List list2(Book book,PageBean pageBean){
Session session = SessionFactoryUtil.getSession();
Transaction transaction = session.beginTransaction();
Map map=new HashMap<>();
String hql="from Book where 1=1";
if(StringUtils.isNotBlank(book.getBookName())) {
hql+=" and bookName like :bookName";
//实际开发需要传过来
map.put("bookName",book.getBookName());
}
//调用baseDao
List list = super.executeQuery(session, hql, pageBean, map);
transaction.commit();
session.close();
return list;
}
public List list3(Book book,PageBean pageBean){
Session session = SessionFactoryUtil.getSession();
Transaction transaction = session.beginTransaction();
Map map=new HashMap<>();
//String hql="select b.bookName,o.orderNo from Book b,Order o where 1=1";
//原生态的查询
//String sql="select b.book_name,o.order_no from t_hibernate_book b,t_hibernate_order o where 1=1";
//创建视图
String sql="select * from book_order";
//List list = session.createQuery(hql).list();
List list = session.createSQLQuery(sql).list();
transaction.commit();
session.close();
return list;
}