記得 session_start();

    class Session{  
      
        /** 
         * 設定session 
         * @param String $name   session name 
         * @param Mixed  $data   session data 
         * @param Int    $expire 超時時間(秒) 
         */  
        public static function set($name, $data, $expire=600){  
            $session_data
 
 = array();  
            $session_data['data'] = $data;  
            $session_data['expire'] = time()+$expire;  
            $_SESSION[$name] = $session_data;  
        }  
      
        /** 
         * 讀取session 
         * @param  String $name  session name 
         * @return Mixed 
         */  
        public
 
 static function get($name){  
            if(isset($_SESSION[$name])){  
                if($_SESSION[$name]['expire']>time()){  
                    return $_SESSION[$name]['data'];  
                }else{  
                    self::clear($name);  
                }  
            }  
            return
 
 false;  
        }  
      
        /** 
         * 清除session 
         * @param  String  $name  session name 
         */  
        private static function clear($name){  
            unset($_SESSION[$name]);  
        }  
      
    }