mongoDB高效分页类

1、使用Skip和limit可以如下做数据分页：Code:page1 = db.things.find().limit(20)page2 = db.things.find().skip(20).limit(20)page3 = db.things.find().skip(40).limit(20)当数据量很小时，这样做分页完全没有问题。但是当数据量很大时，skip操作会变的很慢，应该避免使用。（不止是mongoDb会这样，大部分数据库都是。）可以通过改变查询文档的规则来达到分页效果，避免使用skip来跳过大量的数据。（通过计算，得到下次查询应该从什么地方开始）<?php/mongoDB分页类

2、class Page var $count=''var $size=''var $total=''var $last=''var $link=''var $url=''var $db=''var $orderby=''var $table=''var $set=''var $page=''var $turnto=''var $key = ''public function _constru

3、ct($table = '', $orderby = array(), $count = '', $size = '', $last = '', $theurl = '', $set = '', $next = '', $prev = '')global $DB;$url = SITE_ROOT.strtolower(CLASS_NAME).'/'.METHOD_NAME;$set = $set ? $set : 5;$this->table =

4、 $table;$this->count = $count;$this->size = $size;$this->last = $last;$this->url = $this->url ? $this->url : $url;$this->set = $set;$this->next = $next;$this->prev = $prev;$this->db = $DB;$this->orderby = $orderby;$this->page = GET:UINT('page');$this->p

5、age = $this->page ? $this->page : 1;/$this->page = $this->page > 0 ? $this->page : GET:UINT('search')>0? GET:UINT('search'):1*/; /$this->page= GET:UINT('search');$this->total = ceil($this->count / $this->size);public function show()if($this-&g

6、t;total != 1)$this->get_first();$this->get_prev();$this->get_center();$this->get_next();$this->get_last();$this->get_turnto();if($this->link)$this->link = $this->turnto.$this->link.'共'.$this->total.'页 '.$this->count.'条记录'if($this->turnto

7、)$this->link .= '</form>'return $this->link;/获取首页private function get_first()if($this->page != 1)if($this->total > 0)$this->link.='<a href="'.$this->url.'" title="首页">首页</a>'/获取上一页private function get_prev()if($this-&

8、gt;prev)$this->link.='<a href="'.$this->url.'/page/'.($this->page - 1).'/id/'.$this->prev.'" title="上一页">上一页</a>'/中间显示private function get_center()$left = ($this->set - $this->page >= 0) ? ($this->page - 1) : $th

9、is->set;$right = ($this->total - $this->page > $this->set) ? $this->set : ($this->total - $this->page);if(!$this->last)$rightresult = $this->db->limit($right * $this->size + 1)->order_by($this->orderby)->get($this->table);else$rightresult = $this->d

10、b->limit($right * $this->size + 1)->where_lte($this->key,$this->last)->order_by($this->orderby)->get($this->table);if($this->last)$this->nor_orderby();$leftresult = $this->db->limit($left * $this->size)->where_gt($this->key,$this->last)->order_by

11、($this->orderby)->get($this->table);$start = ($this->page - $this->set) <= 0 ? 1 : ($this->page - $this->set); $end = ($this->page + $this->set + 1 >= $this->total) ? $this->total + 1 : ($this->page + $this->set + 1);$ii = $left;$iii = 0;/显示左边的for($i = $s

12、tart; $i < $end; $i+, $ii-, $iii+)if($this->page = $i)$this->link.='<a style="color:#06F">'.$i.'</a>'else$the_id = $ii * $this->size - 1;if($the_id > 0)$this->link.='<a href="'.$this->url.'/page/'.$i.'/id/'.$l

13、eftresult$the_id$this->key.'" title="第'.$i.'页">'.$i.'</a>'else$the_id = ($iii - $left) * $this->size;$this->link.='<a href="'.$this->url.'/page/'.$i.'/id/'.$rightresult$the_id$this->key.'" title=&

14、quot;第'.$i.'页">'.$i.'</a>'/获取下一页private function get_next()if($this->next)$this->link.='<a href="'.$this->url.'/page/'.($this->page + 1).'/id/'.$this->next.'" title="下一页">下一页</a>'/获取尾页pri

15、vate function get_last()if($this->page != $this->total)$res = $this->count % $this->size;$this->nor_orderby();if($res > 0)$result = $this->db->limit($res)->order_by($this->orderby)->get($this->table);$this->last = $result$res-1$this->key;$this->link.='

16、;<a href="'.$this->url.'/page/'.$this->total.'/id/'.$this->last.'" title="尾页">尾页</a>'else$result = $this->db->limit($this->size)->order_by($this->orderby)->get($this->table);$this->last = $result$this->si

17、ze-1$this->key;$this->link.='<a href="'.$this->url.'/page/'.$this->total.'/id/'.$this->last.'" title="尾页">尾页</a>'/跳转到private function get_turnto()$this->turnto = '<form action="" method="get" onsubmit="window.location=''.$this->url.'/search/'+this.p.value+''.''return false;">转到第 <input type="text" name="p&