PHP面向对象之分页类

 <?php
    class Page
    {
        protected $num;//每页显示条数
        protected $total;//总记录数
        protected $pageCount;//总页数
        protected $current;//当前页码
        protected $offset;//偏移量
        protected $limit;//分页页码

        /**
         * 构造方法
         * @param int  $total 总记录数
         * @param int  $num   每页显示条数
         */
        public function __construct($total,$num=5)
        {
            //1.每页显示条数
            $this->num = $num;
            //2.总记录数
            $this->total = $total;
            //3.总页数
            $this->pageCount = ceil($total/$num);
            //4.偏移量
            $this->offset = ($this->current-1)*$num;
            //5.分页页码
            $this->limit = "{$this->offset},{$this->num}";
            //6.初始化当前页
            $this->current();
        }

        /**
         * 初始化当前页
         */
        public function current(){
            $this->current = isset($_GET['page'])?$_GET['page']:'1';

            //判断当前页最大范围
            if ($this->current>$this->pageCount){
                $this->current = $this->pageCount;
            }

            //判断当前页最小范围
            if ($this->current<1){
                $this->current = 1;
            }
        }

        /**
         * 访问没权限访问的属性
         * @param string $key 想访问的属性
         * @return float|int|string 返回对应要改变的条件
         */
        public function __get($key){
            if ($key == "limit") {
                return $this->limit;
            }
            if ($key == "offset") {
                return $this->offset;
            }
            if ($key == "current") {
                return $this->current;
            }
        }

        /**
         * 处理分页按钮
         * @return string 拼接好的分页按钮
         */
        public function show(){
            //判断初始页码
            $_GET['page'] = isset($_GET['page'])?$_GET['page']:'1';

            //将$_GET值赋给上下变量
            $first = $end = $prev = $next = $_GET;
            // var_dump($prev);

            //上一页
            //判断上一页范围
            if ($this->current-1<1){
                $prev['page'] = 1;
            }else{
                $prev['page'] = $this->current-1;
            }

            //下一页
            //判断下一页范围
            if ($this->current+1>$this->pageCount) {
               $next["page"] = $this->pageCount;
            }else{
                $next['page'] = $this->current+1;
            }

            /*
            首页
            $first['page'] = 1; 

            //尾页
            $end['page'] = $this->pageCount;
            */

            //拼接路径
            $url = "http://".$_SERVER["SERVER_NAME"].$_SERVER["SCRIPT_NAME"];

            //拼接数组url地址栏后缀?传入参数
            //http://xxx/xxx/Page.class.php?page=值
            $prev = http_build_query($prev);
            $next = http_build_query($next);
            // $first = http_build_query($first);
            // $end = http_build_query($end);

            //拼接完整路径
            $prevpath = $url."?".$prev;
            $nextpath = $url."?".$next;
            // $firstpath = $url."?".$first;
            // $endpath = $url."?".$end;

            $str = "共有{$this->total}条记录 共有{$this->pageCount}页 ";
            $str .= "<a href='{$url}?page=1'>首页</a> ";
            $str .= "<a href='{$prevpath}'>上一页</a> ";
            $str .= "<a href='{$nextpath}'>下一页</a> ";
            $str .= "<a href='{$url}?page={$this->pageCount}'>尾页</a> ";
            return $str;
        }
    }
    //自行调试
    $a = new Page(10);
    echo $a->show();
?>