1 
     total = $total;12         if($perpage){13             $this->perpage = $perpage;14         }15 16         if($page){17             $this->page = $page;18         }19     }20     //重要的参数都已拿到，开始创建分页导航，创建分页导航两个步骤，一是保存地址栏参数，二是根据总页数和当前页数计算导航链接，先保存地址栏参数21     public function show(){22         $cnt = ceil($this->total/$this->perpage);23         //分析url地址参数，去掉里面的page，24         $url = $_SERVER['REQUERST_URI']；/*得到诸如 baidu.com?id=3&cat=5$page=9925         //拿到带参数的地址栏后用parse_url()函数把上面路径拆成数组array(26                                                                             [path] =>baidu.com27                                                                             [query] =>id=3&cat=5$page=9928 */29         $parse = parse_url($url);30          //判断有没有参数，也就是数组中有没有query,有了把它再拆开，用parse_str()函数31          $param =array();32          if(isset($parse['query'])){33             $param = parse_str($parse['query']);/*array(34                                                                                     [id]  = 3,35                                                                                     [cat]=5,36                                                                                     [page] =9937          */38          }39 40         //去掉里面的page参数,不管有没有都unset下，41         unset($param['page']);42 43         $url = $parse['path'] . '?';44 45         if(!empty($param)){46             $param = http_build_query($param);//重新拼成id=3&cat=547             $url =$url .$param . '&'; //baidu.com?id=3&cat=548         }49 50           $nav = array();51         $nav[0] = '' . $this->page . '';52 53                for($left = $this->page-1,$right=$this->page+1;($left>=1||$right<=$cnt)&&count($nav) <= 5;) {54 55             if($left >= 1) {56                 array_unshift($nav,'[' . $left . ']');57                 $left -= 1;58             }59 60             if($right <= $cnt) {61                 array_push($nav,'[' . $right . ']');62                 $right += 1;63             }64         }65 66 67 68         return implode('',$nav);69     }70 71 }