hibernate之通用分页

分页原理（思路）
executeQuery(String sql,PageBean pageBean,Clazz clz);
sql： 1.将原生态的sql拼接成计算页数的countSql，计算有多少页数据
2.将原生态的sql拼接成分页语句pageSql,得到查询结果
3.处理结果集

hql： hql在传过来的时候是没有给参数赋值的
1.将原生态的hql拼接成计算页数的countHql，计算有多少页数据
2.将原生态的hql拼接成分页语句pageHql,得到查询结果(hibernate可以调用内置的分页语句)
3.hibernate不用处理结果集

/**
	 * 给query中的变量赋值
	 * @param query 需要赋值的query对象
	 * @param map   key：需要赋值的变量名
	 * 				value： 对应的值
	 */
	private void setParamter(Query query,Map<String, Object> map) {
		if(map == null || map.size() == 0) {
			return ;//结束程序
		}else {
			Object value = null;
			//给query赋值
			for (Entry<String, Object> entry : map.entrySet()) {
				value = entry.getValue();
				//如果获得参数为集合
				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);
				}
			}
		}
		
	}
	

/**
	 * 获得查询条数的hql
	 * @param hql
	 * @return
	 */
	private String getCountSql(String hql) {
		int index = hql.toUpperCase().indexOf("FROM");
		return "select count(*) " + hql.substring(index);
	}

/**
	 * 通用查询
	 * @param hql 查询语句
	 * @param pageBean 分页数据
	 * @param map 查询条件
	 * @param session 
	 * @return
	 */
	public List executeQuery(String hql,PageBean pageBean,Map<String, Object> map,Session session) {
		if(pageBean != null && pageBean.isPagination()) {
			//分页
			String countHql = this.getCountSql(hql);
			Query countQuery = session.createQuery(countHql);//查询total总条数
			this.setParamter(countQuery, map);
			System.out.println("countHql"+countHql);
			List<Long> t = countQuery.list();
//			countQuery.uniqueResult();获取单个
			
			Long total = t.get(0);
			pageBean.setTotal(total+"");
			
			
			Query pageQuery = session.createQuery(hql);
			//给参数设值
			this.setParamter(pageQuery, map);
			pageQuery.setFirstResult(pageBean.getStartIndex());
			pageQuery.setMaxResults(pageBean.getRows());
			
			return pageQuery.list();
		}else {
			//不分页
			Query query = session.createQuery(hql);
			//给参数设值
			this.setParamter(query, map);
			return query.list();
		}
	}

帮助类
PageBean

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 + "]";
	}

StringUtils

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);
	}