docs: public PageResult<Entity> page(Connection conn, Collection<String> fields, Entity where, Page page) throws SQLException {
  		checkConn(conn);
  		
  		//查询全部
  		if(null == page){
  			List<Entity> entityList = this.find(conn, fields, where, new EntityListHandler());
  			final PageResult<Entity> pageResult = new PageResult<Entity>(0, entityList.size(), entityList.size());
  			pageResult.addAll(entityList);
  			return pageResult;
  		}
  		
  		final int count = count(conn, where);
  		PageResultHandler pageResultHandler = PageResultHandler.create(new PageResult<Entity>(page.getPageNumber(), page.getPageSize(), count));
  		return this.page(conn, fields, where, page, pageResultHandler);
  	}