HQL通用分页

HQL通用分页
HQL分页的思路:

1. HQL传过来,拼接countHql
2. 给命名参数赋值(hibernate 5.0 以后占位符?基本不用了)
3. pageBean setTotal（设置符合条件的总页数）
4. 查询你需要的结果集
   命名参数赋值

/**
	 * 给命名参数赋值
	 * 
	 * @param query 预定义参数
	 * @param map 接受参数
	 */

	public void setParameters(Query query, Map map) {
		if (map == null || map.size() == 0)return;
		Object values;
		for (Map.Entry entry : map.entrySet()) {
			values = entry.getValue();

			if (values instanceof Collection) {
				
				values = query.setParameterList(entry.getKey(), (Collection) values);
				
			} else if (values instanceof Object[]) {

				values = query.setParameterList(entry.getKey(), (Object[]) values);

			} else {
				values = query.setParameter(entry.getKey(), values);
			}

		}
	}

接受sql，拼接countHql语句

/**
	 * 拼接HQL countHql
	 *  FROM bas_dict where 1=1 bac_dict like :bsc_dict
	 *  select count(*) ForM bas_dict where 1=1 bac_dict like :bsc_dict 
	 * select bid,bname FROM bas_dict hwere 1=1 bac_dict like :bsc_dict
	 * 
	 * @return
	 */
	private  String getCountHql(String hql) {
		// 获取from的下标
		int indexOf = hql.toUpperCase().indexOf("FROM");
		return "select count(*)" + hql.substring(indexOf);
	}

注意：获取form的下标的作用是避免拼接你传过来的HQL是第三种类型的拼接会出错误
通用分页查询

/**
	 * 通用分页查询
	 * 
	 * @return
	 */
	protected List executeQuery(Session session, String hql, Map map, PageBean pageBean) {
		if (pageBean != null && pageBean.isPagination()) {
			// 获取数据库中总的记录数
			String countHql = getCountHql(hql);
			Query createQuery = session.createQuery(countHql);
			this.setParameters(createQuery, map);
			pageBean.setTotal(createQuery.getSingleResult().toString());

			// 开始分页
			Query query = session.createQuery(hql);
			this.setParameters(query, map);
			query.setFirstResult(pageBean.getStartIndex());
			query.setMaxResults(pageBean.getRows());
			return query.list();

		} else {

			Query query = session.createQuery(hql);
			this.setParameters(query, map);
			return query.list();
		}

	}

pageBean类

public class PageBean {

	private int page = 1;// 页码
	private int rows = 10;// 行数/页大小
	private int total = 0;// 总记录数

	private boolean pagination = true;// 默认分页

	private String url;// 上一次请求的地址
	private Map parameterMap;// 上一次请求的所有参数

	public PageBean() {
		super();
	}

	/**
	 * 对分页bean进行初始化
	 * 
	 * @param request
	 */
	public void setRequest(HttpServletRequest request) {
		// 公共参数
		this.setPage(request.getParameter("page"));
		this.setRows(request.getParameter("rows"));
		this.setPagination(request.getParameter("pagination"));

		// 请求地址和请求参数
		this.setUrl(request.getContextPath() + request.getServletPath());
		this.setParameterMap(request.getParameterMap());
	}

	public String getUrl() {
		return url;
	}

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

	public Map getParameterMap() {
		return parameterMap;
	}

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

	public int getPage() {
		return page;
	}

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

	public void setPage(String page) {
		if (null != page && !"".equals(page.trim())) {
			this.page = Integer.parseInt(page);
		}
	}

	public int getRows() {
		return rows;
	}

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

	public void setRows(String rows) {
		if (null != rows && !"".equals(rows.trim())) {
			this.rows = Integer.parseInt(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 void setPagination(String pagination) {
		if ("false".equals(pagination)) {
			this.pagination = false;
		}
	}

	/**
	 * 下一页
	 * 
	 * @return
	 */
	public int getNextPage() {
		int nextPage = page + 1;
		if (nextPage > this.getMaxPage()) {
			nextPage = this.getMaxPage();
		}
		return nextPage;
	}

	/**
	 * 上一页
	 * 
	 * @return
	 */
	public int getPreviousPage() {
		int previousPage = page - 1;
		if (previousPage < 1) {
			previousPage = 1;
		}
		return previousPage;
	}

	/**
	 * 最大页码
	 * 
	 * @return
	 */
	public int getMaxPage() {
		return total % rows == 0 ? total / rows : total / rows + 1;
	}

	/**
	 * 起始记录的下标
	 * 
	 * @return
	 */
	public int getStartIndex() {
		return (page - 1) * rows;
	}

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

}

StringsUtils工具类

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);
	}

}