<?php
/**

*/
class Page{
	protected $url;			//地址
	protected $allnum;		//总记录数
	protected $current;		//当前页码
	protected $pagesize;		//每页显示多少条记录
	protected $postfix;		//后缀
	protected $style;			//显示样式 共3种样式,1 2 3 分别表示前5后4,前3后3,前4后4
	
	public function __construct($url,$allnum,$current,$pagesize=10,$postfix='',$style=1){
		$this->url=$url;
		$this->allnum=$allnum;
		$this->current=$current;
		$this->pagesize=$pagesize;
		$this->postfix=$postfix;
		$this->style=$style;
	}
	
	//获取总页数
	protected function maxPageNum(){
		$max=ceil($this->allnum/$this->pagesize);
		//页码超限校正
		if($this->current>$max){
			$this->current=$max;
		}
		if($this->current<1){
			$this->current=1;
		}
		return $max;
	}
	
	//获得第一页链接完整html str
	protected function firstUrl(){
		if($this->current!=1)
		{
			return '<span id="firstpage"><a href="'.$this->getUrl(1).'" title="查看第一页">首页</a></span>';
		}else{
			return '<span id="firstpage"><a>首页</a></span>';
		}
	}
	
	//获得上一页链接完整html str
	protected function prevUrl(){
		if($this->current<=1){
			$fullurl='<span id="prevpage"><a>上一页</a></span>';
		}else{
			$fullurl=$this->url.($this->current-1).$this->postfix;
			$fullurl='<span id="prevpage" title="查看上一页"><a href="'.$fullurl.'">上一页</a></span>';
		}
		return $fullurl;
	}
	
	//获得下一页链接完整html str
	protected function nextUrl(){
		if($this->current>=$this->maxPageNum()){
			$fullurl='<span id="nextpage"><a>下一页</a></span>';
		}else{
			$fullurl=$this->url.($this->current+1).$this->postfix;
			$fullurl='<span id="nextpage" title="查看下一页"><a href="'.$fullurl.'">下一页</a></span>';
		}
		return $fullurl;
	}
	
	//获得最后一页链接完整html str
	protected function lastUrl(){
		if($this->current>=$this->maxPageNum()){
			$fullurl='<span id="lastpage"><a>末页</a></span>';
		}else{
			$fullurl=$this->url.$this->maxPageNum().$this->postfix;
			$fullurl='<span id="lastpage" title="最后一页"><a href="'.$fullurl.'">末页</a></span>';
		}
		return $fullurl;
	}
	
	//获得指定页码完整url
	protected function getUrl($pageno){
		return $this->url.$pageno.$this->postfix;
	}
	
	//指定显示样式
	protected function getStyle(){
		switch($this->style){
			case 1:
				$before=5;
				$after=4;
				break;
			case 2:
				$before=3;
				$after=3;
				break;
			case 3:
				$before=4;
				$after=4;
				break;
			default :
				$before=5;
				$after=4;
		}
		
		return array($before,$after);
	}
	
	//获得中间URL 1 2 3 4 5 ⑥ 7 8 9 10
	protected function getMiddelUrl(){
		$max=$this->maxPageNum();	//先获取总页,可校正当前页超限问题
		$current=$this->current;	//当前页码必须合法,才能保证下面的页码范围一定正确
		//得到当前样式
		list($before,$after)=$this->getStyle();
		$startno=$current-$before;		//起始页码
		$endno=$current+$after;			//终止页码
		
		//为保证输出始终符合要求,在页面不超限前提下,起始页增加,则终止页必须增加,反之同理.
		while($endno>$max||$startno<1){
			if($endno>$max){		//终止页码超界
				$endno--;
				if($startno>1){
					$startno--;
				}
			}
			if($startno<1){			//起始页码超界
				$startno++;
				if($endno<$max){
					$endno++;
				}
			}
		}
		$str='';					//用于保存整个html str
		for($i=$startno;$i<=$endno;$i++){
			$currenturl=$this->getUrl($i);
			if($i!=$current){
				$str.="<a href='{$currenturl}'>{$i}</a>";
			}else{
				$str.='<span id="current"><a>'.$i.'</a></span>';
			}
		}
		return $str;
	}
	
	//返回完整分页html字符串
	public function getPageStr(){
		$str='<div id="pagelist">'.$this->firstUrl().$this->prevUrl();
		$str.=$this->getMiddelUrl();
		$str.=$this->nextUrl().$this->lastUrl().'<span id="allpagesize">共'.$this->maxPageNum().'页'.$this->allnum.'条</span></div>';
		return $str;
	}
}
?>

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