PHP权限控制类

<?php   /*** 权限控制类*/    class include_purview   {       /**      * 类的唯一实例      */      private static $instance;              /**      * 权限常量      */      const SELECT = 0x1; //查询       const CREATE = 0x2; //添加       const EDIT    = 0x4; //修改       const DELETE = 0x8; //删除              /**      * 角色      */      private $annoy = ''; //匿名用户       private $user   = ''; //注册用户       private $admin = ''; //管理用户       private $usertype = 'annoy';       private $hashtable = array(1=>'查询',2=>'添加',4=>'修改',8=>'删除');              /**      *      */      public function __set($name,$value)        {           if ($name == 'usertype')            {               if ($value != '')                {                   $this->usertype = $value;                }            }        }              /**      * 构造函数 给角色赋予权限      */      private function __construct()        {           $this->annoy = self::SELECT;           $this->user = self::SELECT | self::CREATE;           $this->admin = self::SELECT | self::CREATE | self::EDIT | self::DELETE;        }              /**      * 获取类的唯一实例      */      public static function getInstance()        {           if (self::$instance === null){                self::$instance = new include_purview();            }           return self::$instance;        }              /**      * 检查权限      *      * @param $usertype 角色      * @param $purview 权限      */      public function check($purview)        {           if ($this->{$this->usertype} & $purview)            {               return true;            }           return false;        }              /**      * 给角色加权限      */      public function addPur($purview)        {           $this->{$this->usertype} |= $purview;        }              /**      * 给角色减权限      */      public function delPur($purview)        {           $this->{$this->usertype} ^= $purview;        }              /**      * 返回角色拥有的权限      */      public function getPur()        {           $arr = array();           foreach ($this->hashtable as $k => $v)            {               if ($k & $this->{$this->usertype})                {                   $arr[] = $v;                }            }           return $arr;        }   } 

/** * 示例 * 在session中读用户组  */@session_start();$_SESSION['role'] = 'user';//获取权限类的实例 $pruview = include_purview::getInstance();//设置角色 $pruview->usertype = $_SESSION['role'];//获取该角色拥有的权限 $arr = $pruview->getpur();echo '该用户的权限有:' . join(',', $arr) . "\n";//判断执行的操作是否有权限 if (true === $pruview->check(include_purview::CREATE)){create(); //要执行的操作 }else{exit('您没有权限!');}//去掉用户的添加权限 $pruview->delPur(include_purview::CREATE);$arr = $pruview->getpur();echo '该用户的权限有:' . join(',', $arr) . "\n";//执行添加操作 if (true === $pruview->check(include_purview::CREATE)){create(); //要执行的操作 }else{echo '您没有权限!' . "\n";}//加上用户的添加权限 $pruview->addPur(include_purview::CREATE);$arr = $pruview->getpur();echo '该用户的权限有:' . join(',', $arr) . "\n";//执行添加操作 if (true === $pruview->check(include_purview::CREATE)){create(); //要执行的操作 }else{exit('您没有权限!');}//具体的操作 function create(){echo '执行了添加操作' . "\n";}