class Helper_Page{

/** 总信息数 */
var $infoCount;
/** 总页数 */
var $pageCount;
/** 每页显示条数　*/
var $items;
/** 当前页码 */
var $pageNo;
/** 查询的起始位置　*/
var $startPos;
/** 下一页　*/
var $nextPageNo;
/** 上一页　*/
var $prevPageNo;

function Helper_Page($infoCount, $items, $pageNo)
{
$this->infoCount = $infoCount;
$this->items = $items;
$this->pageNo = $pageNo;
$this->pageCount = $this->GetPageCount();
$this->AdjustPageNo();
$this->startPos = $this->GetStartPos();
}
function AdjustPageNo()
{
if($this->pageNo == '' || $this->pageNo < 1)
$this->pageNo = 1;
if ($this->pageNo > $this->pageCount)
$this->pageNo = $this->pageCount;
}
/**
* 下一页
*/
function GoToNextPage()
{
$nextPageNo = $this->pageNo + 1;
if ($nextPageNo > $this->pageCount)
{
$this->nextPageNo = $this->pageCount;
return false;
}
$this->nextPageNo = $nextPageNo;
return true;
}
/**
* 上一页
*/
function GotoPrevPage()
{
$prevPageNo = $this->pageNo - 1;
if ($prevPageNo < 1)
{
$this->prevPageNo = 1;
return false;
}
$this->prevPageNo = $prevPageNo;
return true;
}
function GetPageCount()
{
return ceil($this->infoCount / $this->items);
}
function GetStartPos()
{
return ($this->pageNo - 1) * $this->items;
}
}