hibernate之HQL

package com.liuwenwu.five.test;

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.liuwenwu.four.entity.Book;
import com.liuwenwu.two.util.SessionFactoryUtils;

public class HqlTest {
    private Session session;
    private Transaction transaction;
    
    
    @Before
    public void before() {
//        方法执行之前执行
        session = SessionFactoryUtils.openSession();
        transaction = session.beginTransaction();
    }
    
    @After
    public void after() {
//        方法执行之后执行
        transaction.commit();
        session.close();
    }
    
    /**
     * 返回对象（多个）
     */
    @Test
    public void testList1() {
        Query query = session.createQuery("from Book");
        List<Book> list = query.list();
        for (Book b : list) {
            System.out.println(b);
        }
    }
    
    /**
     * 返回单个列段，用字符串就可以接收
     */
    @Test
    public void testList2() {
        Query query = session.createQuery("select b.bookName as ss from Book b");
        List<String> list = query.list();
        for (String b : list) {
            System.out.println(b);
        }
    }
    
    /**
     * 查两个列段及以上，默认返回的是Object【】
     */
    @Test
    public void testList3() {
        Query query = session.createQuery("select b.bookId,b.bookName as ss from Book b");
        List<Object[]> list = query.list();
        for (Object[] b : list) {
            System.out.println(Arrays.toString(b));
        }
    }
    
    /**
     * 注意map是函数，所以不区分大小写，返回的是map集合
     */
    @Test
    public void testList4() {
        Query query = session.createQuery("select new mAp(b.bookId,b.bookName) from Book b");
        List<Map> list = query.list();
        for (Map b : list) {
            System.out.println(b);
        }
    }
    
    /**
     * 查两个列段及以上，也可返回对象，前提是有对应的构造函数
     */
    @Test
    public void testList5() {
        Query query = session.createQuery("select new Book(b.bookId,b.bookName) from Book b");
        List<Book> list = query.list();
        for (Book b : list) {
            System.out.println(b);
        }
    }

    /**
     * HQL语句支持占位符(命名参数)
     */
    @Test
    public void testList6() {
//        Query query = session.createQuery("from Book where bookId = :bookId");
//        query.setParameter("bookId", 1);
//        Book b = (Book) query.getSingleResult();
//        System.out.println(b);
//        数组
        Query query = session.createQuery("from Book where bookId in (:bookIds)");
        query.setParameterList("bookIds", new Integer[] {1,2,4});
//        集合
//        List<Integer> params = new ArrayList<Integer>();
//        params.add(1);
//        params.add(2);
//        params.add(4);
//        query.setParameterList("bookIds", params);
        List<Book> list = query.list();
        for (Book b : list) {
            System.out.println(b);
        }
    }

    /**
     * HQL支持连接查询
     */
    @Test
    public void testList7() {
//        sql写法：select * from t_hibernate_order o,t_hibernate_order_item oi where o.order_id=oi.oid
        Query query = session.createQuery("select o.orderNo,oi.quantity from Order o,OrderItem oi where o = oi.order");
        List<Object[]> list = query.list();
        for (Object[] b : list) {
            System.out.println(Arrays.toString(b));
        }
    }

    /**
     * HQL支持聚合函数
     */
    @Test
    public void testList8() {
        Query query = session.createQuery("select count(*) from Book");
//        getSingleResult是用来获取单条记录的
        Long singleResult = (Long) query.getSingleResult();
        System.out.println(singleResult);
    }

    /**
     * HQL分页
     * sql limit 5,5
     * hql from Book
     *       同样的可以自动根据方言生成分页语句
     *         setFirstResult：设置起始下标
     *         setMaxResults：设置偏移量
     * mysql:hql limit 5,5
     * oracle:select * from (select t.*,rownum rn hql t where t.rn >5)t1 where t1.rn<10
     * 
     */
    @Test
    public void testList9() {
        Query query = session.createQuery("from Book");
        query.setFirstResult(2);
        query.setMaxResults(3);
        List<Book> list = query.list();
        for (Book b : list) {
            System.out.println(b);
        }
    }

package com.liuwenwu.five.util;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;

/**
 * 分页工具类
 *
 */
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<String, String[]> parameterMap;
    // 获取上一次访问后台的url
    private String url;

    /**
     * 初始化pagebean
     * 
     * @param req
     */
    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<String, String[]> getParameterMap() {
        return parameterMap;
    }

    public void setParameterMap(Map<String, String[]> parameterMap) {
        this.parameterMap = parameterMap;
    }

    public String getUrl() {
        return url;
    }

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

    /**
     * 获得起始记录的下标
     * 
     * @return
     */
    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 + "]";
    }
}

package com.liuwenwu.five.util;

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

    /**
     * 如果字符串等于null或去空格后等于""，则返回true，否则返回false
     * 
     * @param s
     * @return
     */
    public static boolean isBlank(String s) {
        boolean b = false;
        if (null == s || s.trim().equals("")) {
            b = true;
        }
        return b;
    }
    
    /**
     * 如果字符串不等于null或去空格后不等于""，则返回true，否则返回false
     * 
     * @param s
     * @return
     */
    public static boolean isNotBlank(String s) {
        return !isBlank(s);
    }
}

    /**
     * 需求：
     *        写一个带查询条件并且能分页的方法
     * @param book
     * @param pageBean
     * @return
     */
    public List<Book> list1(Book book,PageBean pageBean) {
        Session session = SessionFactoryUtils.openSession();
        Transaction transaction = session.beginTransaction();
        String bookName = book.getBookName();
        String hql="from Book where 1=1";
        if(StringUtils.isNotBlank(bookName)) {
            hql+=" and bookName like :bookName";
        }
//        query相当于前面sql所用的prepareStatement
        Query query = session.createQuery(hql);
        if(StringUtils.isNotBlank(bookName)) {
            query.setParameter("bookName", bookName);
        }
//        通过写上述代码会发现，同样的if判断写了两次
        
//        下面这个代码每个实体类分页都得写
        if(pageBean!=null&& pageBean.isPagination()) {
            query.setFirstResult(pageBean.getStartIndex());
            query.setMaxResults(pageBean.getRows());
        }
        List<Book> list=query.list();
        transaction.commit();
        session.close();
        return list;
    }

    /**
     * 带查询条件的分页的方法测试
     */
    @Test
    public void list1() {
        Book book=new Book();
        PageBean pageBean=new PageBean();
//        pageBean.setPage(2);
        book.setBookName("%少年阿宾%");
        List<Book> list1 = this.bookDao.list1(book, pageBean);
        for (Book b : list1) {
            System.out.println(b);
        }
    }

Book [bookId=5, bookName=少年阿宾, price=10.0]
Book [bookId=6, bookName=少年阿宾2, price=10.0]

package com.liuwenwu.five.util;

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;

/**
 * 1、设置参数的问题
 * 2、分页代码重复的问题
 * sql的通用分页
 * getCountSql(sql)
 *     select count(1) from (sql) t
 * 
 * getCountHql(hql)
 *     hql="from Book where bookName like :bookName"
 *     hql="select * from new Book(bid,bookName) where bookName like :bookName"
 * select count(1) hql
 * 
 * @author ASUS
 *
 */
public class BaseDao {
    /**
     * 通用的参数设置方法
     * @param map    参数键值对集合
     * @param query    预定义处理hql对象
     */
    public void setParam(Map<String, Object> map,Query query) {
        if(map!=null&&map.size()>0) {
            Object value=null;
            Set<Entry<String, Object>> entrySet = map.entrySet();
            for (Entry<String, Object> entry : entrySet) {
//                例子中的少年阿宾，但有时候它并不是单纯的字符串，可能是数字比如爱好，也可能是集合
                value=entry.getValue();
                //数组
                if(value instanceof Object[]) {
                    query.setParameterList(entry.getKey(), (Object[])value);
                }
                //集合
                else if(value instanceof Collection) {
                    query.setParameterList(entry.getKey(), (Collection)value);
                }
                //基本数据类型
                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);
    }    
    
    /**
     * 通用查询方法
     * @param session
     * @param map
     * @param hql
     * @param pageBean
     * @return
     */
    public List executeQuery(Session session,Map<String, Object> 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语句执行对象参数赋值，有多少赋值多少
            this.setParam(map, query);
            //起始下标
            query.setFirstResult(pageBean.getStartIndex());
            //偏移量
            query.setMaxResults(pageBean.getRows());
            list=query.list();
        }
        else {
            Query query = session.createQuery(hql);
//            给预定义hql语句执行对象参数赋值，有多少赋值多少
            this.setParam(map, query);
            list=query.list();
        }
        return list;
    }    
}

    /**
     * 继承BaseDao的通用分页加查询方法
     * @param book
     * @param pageBean
     * @return
     */
    public List<Book> list2(Book book,PageBean pageBean) {
        Session session = SessionFactoryUtils.openSession();
        Transaction transaction = session.beginTransaction();
        
        String bookName = book.getBookName();
        Map<String, Object> map=new HashMap<>();
        String hql="from Book where 1=1";
        if(StringUtils.isNotBlank(bookName)) {
            hql+=" and bookName like :bookName";
            map.put("bookName", bookName);
        }    
        List<Book> list=super.executeQuery(session, map, hql, pageBean);
        
        transaction.commit();
        session.close();
        return list;
    }

    /**
     * 继承BaseDao的通用带查询条件的分页的方法测试
     */
    @Test
    public void list2() {
        Book book=new Book();
        PageBean pageBean=new PageBean();
//        pageBean.setPage(2);
        pageBean.setPagination(false);
//        book.setBookName("%少年阿宾%");
        List<Book> list1 = this.bookDao.list2(book, pageBean);
        for (Book b : list1) {
            System.out.println(b);
        }
    }

Book [bookId=1, bookName=西游记, price=50.0]
Book [bookId=2, bookName=红楼梦, price=50.0]
Book [bookId=3, bookName=水浒, price=50.0]
Book [bookId=4, bookName=三国演义, price=50.0]
Book [bookId=5, bookName=少年阿宾, price=10.0]
Book [bookId=6, bookName=少年阿宾2, price=10.0]
Book [bookId=7, bookName=诡秘之主, price=99.0]