Hibernate之HQL

一：了解HQL

1.什么是hql

HQL是Hibernate Query Language的缩写

2.hql和sql的区别

3.处理返回的结果集

1.单个对象

语法：select没有逗号

2.Object[]

语法：b.bookId,b.bookName

3.Map

语法：new Map(b.bookId as bid ,b.bookName as bname)

4.new 构造方法(attr1,attr2)

语法：new Book(b.bookId,b.price)   单个列段

4.hql中使用占位符

1. ？占位符

语法：从下标0开始计算位置，hibernate5之后就不再支持 ?占位符

2.命名参数  

二：hql的初步使用

HqlTest

package com.sg.three.hql;

import java.util.Arrays;
import java.util.List;
import java.util.Map;

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.query.Query;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.sg.two.entity.Book;
import com.sg.two.util.SessionFactoryUtil;

public class HqlTest {
	private Session session;
	private Transaction transaction;
	
	@Before
	public void before() {
		session = SessionFactoryUtil.getSession();
		transaction = session.beginTransaction();
	}
	
	@After
	public void after() {
		transaction.commit();
		session.close();
	}
	
	
	@Test
	public void testList1() {
		Query query = session.createQuery("from Book");
		List list = query.list();
		for (Book b : list) {
			System.out.println(b);
		}
	}
	
	
	@Test
	public void testList2() {
		Query query = session.createQuery("select b.bookName as ss from Book b");
		List list = query.list();
		for (String b : list) {
			System.out.println(b);
		}
	}
	
	
	@Test
	public void testList3() {
		Query query = session.createQuery("select b.bookId,b.bookName as ss from Book b");
		List list = query.list();
		for (Object[] b : list) {
			System.out.println(Arrays.toString(b));
		}
	}
	
	
	@Test
	public void testList4() {
		Query query = session.createQuery("select new mAp(b.bookId,b.bookName) from Book b");
		List

分析：

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 结果展示：

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 结果展示：

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结果展示：

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结果展示：

 

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结果展示：

 验证图上注释

结果展示：

 

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结果展示：

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结果展示：

 

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结果展示：

三：分页

分页所需要用到的类

PageBean

package com.sg.three.hql;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;


public class PageBean {

	private int page = 1;// 页码

	private int rows = 3;// 页大小

	private int total = 0;// 总记录数

	private boolean pagination = true;// 是否分页
	// 获取前台向后台提交的所有参数
	private Map parameterMap;
	// 获取上一次访问后台的url
	private String url;

	
	public void setRequest(HttpServletRequest req) {
		this.setPage(req.getParameter("page"));
		this.setRows(req.getParameter("rows"));
		// 只有jsp页面上填写pagination=false才是不分页
		this.setPagination(!"fasle".equals(req.getParameter("pagination")));
		this.setParameterMap(req.getParameterMap());
		this.setUrl(req.getRequestURL().toString());
	}

	public int getMaxPage() {
		return this.total % this.rows == 0 ? this.total / this.rows : this.total / this.rows + 1;
	}

	public int nextPage() {
		return this.page < this.getMaxPage() ? this.page + 1 : this.getMaxPage();
	}

	public int previousPage() {
		return this.page > 1 ? this.page - 1 : 1;
	}

	public PageBean() {
		super();
	}

	public int getPage() {
		return page;
	}

	public void setPage(int page) {
		this.page = page;
	}

	public void setPage(String page) {
		this.page = StringUtils.isBlank(page) ? this.page : Integer.valueOf(page);
	}

	public int getRows() {
		return rows;
	}

	public void setRows(int rows) {
		this.rows = rows;
	}

	public void setRows(String rows) {
		this.rows = StringUtils.isBlank(rows) ? this.rows : Integer.valueOf(rows);
	}

	public int getTotal() {
		return total;
	}

	public void setTotal(int total) {
		this.total = total;
	}

	public void setTotal(String total) {
		this.total = Integer.parseInt(total);
	}

	public boolean isPagination() {
		return pagination;
	}

	public void setPagination(boolean pagination) {
		this.pagination = pagination;
	}

	public Map getParameterMap() {
		return parameterMap;
	}

	public void setParameterMap(Map parameterMap) {
		this.parameterMap = parameterMap;
	}

	public String getUrl() {
		return url;
	}

	public void setUrl(String url) {
		this.url = url;
	}

	
	public int getStartIndex() {
		return (this.page - 1) * this.rows;
	}

	@Override
	public String toString() {
		return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination
				+ ", parameterMap=" + parameterMap + ", url=" + url + "]";
	}

}

StringUtils

package com.sg.three.hql;

public class StringUtils {
	// 私有的构造方法，保护此类不能在外部实例化
	private StringUtils() {
	}

	
	public static boolean isBlank(String s) {
		boolean b = false;
		if (null == s || s.trim().equals("")) {
			b = true;
		}
		return b;
	}
	
	
	public static boolean isNotBlank(String s) {
		return !isBlank(s);
	}

}

baseDao

开发思路

baseDao的开发思路
1.完成了——个基础版本的查询方法
2.分析:
    分析共同之处
        1.都有非空判断
        2.都有query对象
        3.具体值从对象/Map
        4．都需要分页
            query.setFirstResult(2);//起始下标
            query.setMaxResults (3);//偏移量
        注意:分页是与Pagebean的total，是优先查询出符合条件的总记录数
3.解决方案
        select count(*)from Book

package com.sg.three.dao;

import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.hibernate.Session;
import org.hibernate.query.Query;

import com.sg.three.hql.PageBean;


public class baseDao {

	
	public void setParam(Map map, Query query) {
		if (map != null && map.size() > 0) {
			Object value = null;
			Set> entrySet = map.entrySet();
			for (Entry entry : entrySet) {
				// 例子的圣墟，但是有的时候它并不是单纯的字符串，可能是数组比如爱好，也可能是集合
				value = entry.getValue();
				if (value instanceof Object[]) {
					query.setParameterList(entry.getKey(), (Object[]) value);
				} else if (value instanceof Collection) {
					query.setParameterList(entry.getKey(), (Collection) value);
				} else {
					query.setParameter(entry.getKey(), value);
				}
			}
		}
	}

	public String getCountHql(String hql) {
		// hql = "from Book where bookName like :bookName"
		// * hql = "select * from new Book(bid,bookName) where bookName like :bookName"
		int index = hql.toUpperCase().indexOf("FROM");
		return "select count(*) " + hql.substring(index);
	}
	
	
	public List executeQuery(Session session,Map map,String hql,PageBean pageBean) {
		List list = null;
		if(pageBean != null && pageBean.isPagination()) {
			String countHql = getCountHql(hql);
			Query countQuery = session.createQuery(countHql);
			this.setParam(map, countQuery);
			pageBean.setTotal(countQuery.getSingleResult().toString());
			
			Query query = session.createQuery(hql);
//			给预定义hql语句执行对象中的参数赋值，有多少赋值多少
			this.setParam(map, query);
			query.setFirstResult(pageBean.getStartIndex());
			query.setMaxResults(pageBean.getRows());
			list = query.list();
		}else {
			Query query = session.createQuery(hql);
//			给预定义hql语句执行对象中的参数赋值，有多少赋值多少
			this.setParam(map, query);
			list = query.list();
		}
		return list;
	}

}

BookDao

package com.sg.two.dao;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.hibernate.Hibernate;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.query.Query;

import com.sg.three.dao.baseDao;
import com.sg.three.hql.PageBean;
import com.sg.three.hql.StringUtils;
import com.sg.two.entity.Book;
import com.sg.two.entity.Category;
import com.sg.two.util.SessionFactoryUtil;


public class BookDao extends baseDao{
	public Integer addBook(Book book) {
		Session session = SessionFactoryUtil.getSession();
		Transaction transaction = session.beginTransaction();
		Integer bid = (Integer) session.save(book);
		transaction.commit();
		session.close();
		return bid;
	}
	
	public Integer addCategory(Category category) {
		Session session = SessionFactoryUtil.getSession();
		Transaction transaction = session.beginTransaction();
		Integer cid = (Integer) session.save(category);
		transaction.commit();
		session.close();
		return cid;
	}
	
	public Category getCategory(Category category) {
		Session session = SessionFactoryUtil.getSession();
		Transaction transaction = session.beginTransaction();
		Category c = session.get(Category.class, category.getCategoryId());
		transaction.commit();
		session.close();
		return c;
	}
	
	public Book getBook(Book book) {
		Session session = SessionFactoryUtil.getSession();
		Transaction transaction = session.beginTransaction();
		Book b = session.get(Book.class, book.getBookId());
		if (b != null && new Integer(1).equals(book.getInitCategories())) {
			Hibernate.initialize(b.getCategories());
		}
		transaction.commit();
		session.close();
		return b;
	}
	
	public void delBook(Book book) {
		Session session = SessionFactoryUtil.getSession();
		Transaction transaction = session.beginTransaction();
		session.delete(book);
		transaction.commit();
		session.close();
	}
	
	public void delCategory(Category category) {
		Session session = SessionFactoryUtil.getSession();
		Transaction transaction = session.beginTransaction();
		Category c = session.get(Category.class, category.getCategoryId());
		if(c!=null) {
			for (Book b : c.getBooks()) {
//				通过在被控方通过主控方来解除关联关系，最后被控方再做删除
				b.getCategories().remove(c);
			}
		}
		session.delete(c);
		transaction.commit();
		session.close();
	}
	
	
	
	
	public List list(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);
		
		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();
		String hql = "from Book where 1 = 1";
		Map map = new HashMap();

		if (StringUtils.isNotBlank(book.getBookName())) {
			hql += " and bookName like :bookName";
			map.put("bookName", book.getBookName());
		}
		List list = super.executeQuery(session, map, hql, pageBean);
		transaction.commit();
		session.close();
		return list;
	}
	
	
	public List list3(Book book, PageBean pageBean) {
//		String sql = "select b.*,o.* from t_hibernate_book b,t_hibernate_Order o";
		String sql = "select * from t_hibernate_book";
		Session session = SessionFactoryUtil.getSession();
		Transaction transaction = session.beginTransaction();
		List list = session.createSQLQuery(sql).list();
		transaction.commit();
		session.close();
		return list;
	}
}

1.使用原生sql

 结果展示：

2.使用BsaeDao

结果展示（这边把每页显示几条改成了五条）

3.在hibernate中使用原生sql

 结果展示：

 

 拜拜了各位！！！