HQL的通用分页

通过书籍名字模糊查询&分页的功能，通常情况下可以如下写查询的方法，但如果查询维度较多且比较麻烦。

新写一个BaseDao代码处理:

package com.zking.eight.util;

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

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

/**
 * 分页:
 * jdbc:
 * executeQuery(String sql,PageBean pageBean,Class clz)
 * sql: select * from t_hibernate_book where book_name like '%?%'
 *      select * from t_hibernate_book where book_name like '%圣墟%'
 *
 *    countSql=select count(*) from (sql) t;
 *
 *分页:
 *1、sql--->转成countSql(查符合条件的总记录数)--->total-->给到pageBean
 *2、sql-->转成分页sql-->(交给entitybasedao)result
 *3、处理结果集
 *
 *hql:
 *  select * from Book where bookName like '%:bookName%'
 *     select count(*) from (hql) t
 *1、hql--->countHql--->total-->pageBean
 *2、sql-->sql-->result(hibernate调用内置接口自动生成分页语句，查询结果)
 *
 * @author Administrator
 */
public class BaseDao {

	private void setParameter(Query query,Map map) {
		if (map == null || map.size() == 0) {
			 return;
		}
		Object value=null;
		//给value赋值
		for (Map.Entry entry : map.entrySet()) {
			value = entry.getValue();
			if (value instanceof Collection) {
				query.setParameterList(entry.getKey(), (Collection) value);
			}
			else if (value instanceof Object[]) {
				query.setParameterList(entry.getKey(), (Object[]) value);
			}
			else {
				query.setParameter(entry.getKey(),value);
			}
		}		
	}
	
	private String getcountHql(String hql) {
		int index= hql.toUpperCase().indexOf("FROM");
		return "select count(*)"+hql.substring(index);
		
	}
	
	public List excuteQuery(String hql,PageBean pageBean,Map map,Session session) {
		if (pageBean != null && pageBean.isPagination()) {
			String countHql = getcountHql(hql);
			Query countQuery = session.createQuery(countHql);
            this.setParameter(countQuery, map);
			String total = countQuery.getSingleResult().toString();
			pageBean.setTotal(total);
			
			Query pageQuery = session.createQuery(hql);
			this.setParameter(pageQuery, map);
			pageQuery.setFirstResult(pageBean.getStartIndex());
			pageQuery.setMaxResults(pageBean.getRows());			
			return pageQuery.list();
		}
		else {
			Query query = session.createQuery(hql);
			this.setParameter(query, map);
			return null;
		}
		  
	}
}

PageBean代码:

package com.zking.eight.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 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 getParameterMap() {
		return parameterMap;
	}

	public void setParameterMap(Map 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 + "]";
	}

}

StringUtils代码：

package com.zking.eight.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);
	}

}