php中Zend_Auth和Zend_Acl进行登录认证及根据用户角色

<?php
require_once 'Zend/Auth/Adapter/Interface.php';
class Auth implements Zend_Auth_Adapter_Interface{
    private $_useraccount;
    private $_password;
    private $_db;
    /**
     * 构造函数 设置用户名和密码 数据连接对象  
     *
     * @return void     
     */
    public function __construct($useraccount,$password,$db){  
        $this->_useraccount = $useraccount;
        $this->_password      = $password;
        $this->_db             = $db;
    }
   
    /**    
     * 进行认证 
     * @throws Zend_Auth_Adapter_Exception   
     * @return Zend_Auth_Result
     *
     */
    public function authenticate()
    {
        //默认情况下是认证失败
        $authResult = array(
            'code'     => Zend_Auth_Result::FAILURE,//详参：Zend_Auth_Result
            'identity' => '',
            'info' => array()
           );
          
           //获得登录用户信息
        $result = $this->_getAccountData();
               
        if(isset($result)&&!empty($result)) {//认证成功,则将用户信息存储到session中
            $authResult = array(
                'code'     => Zend_Auth_Result::SUCCESS,
                'identity' => $result['name'],
                'info'     => array('status'=>$result['status'])
            );
            //角色存储  个人缓存空间
            $namespace = Zend_Auth::getInstance()//单例模式
                                 -> getStorage()
                                 -> getNamespace();
            $_SESSION[$namespace]['role']     = $result['group_id'];//所属用户组
            $_SESSION[$namespace]['userInfo'] = $result;
            $_SESSION[$namespace]['userInfo']['lastLoginTime'] = $result['login_time'];
            $_SESSION[$namespace]['userInfo']['lastLoginIp']   = $result['login_ip'];          
//            $_SESSION[$namespace]['userInfo']['password']   = $result['password'];//密码是很重要的，不要写到session中
        }
       
        return new Zend_Auth_Result($authResult['code'], $authResult['identity'], $authResult['info']);
    }
    /**
     * 用户密码加密
     * @param $pwd  原始密码
     * @return string  加密后的密码字符串
     *
     */
    static public function encryptionType($pwd=null) {
        $pwd = md5($pwd);
        return $pwd;
    }
    /**
     * 获得用户数据结构
     *
     * @todo 整理密码的公共类
     */
    private function _getAccountData(){
        $resArr = array();
        $sysUserObj = Base_Dao_Factory::getObject('Admin_Models_User');
        //先登录普通会员帐号
        $data = array(
            'login_name' => $this->_useraccount,
            'login_pwd'  => $this->encryptionType($this->_password)
        );
        $result = $sysUserObj->login($data);
        //判断是否有数据,是则赋值
        if ($result) {
            if (!empty($result[0])) {
                $resArr = $result[0];
            }
        }
        return $resArr;
    }
}