/**  
 *@blog<http://www.phpddt.com> 
 */  
public function do_login()  
{  
      
    if ($this->form_validation->run('do_login') == FALSE)  
    {  
       $this->load->view('login');  
    }  
    else  
    {  
       $usr = $this->input->post("username",TRUE);  
       $psw = $this->input->post("password",TRUE);  
       $user = $this->user_mdl->validate_user($usr,$psw);  
       if($user)  
       {  
            /** 验证成功，更新用户信息，设置session,自动跳转 */  
            $data['last_active'] = time();  
            $this->user_mdl->update_user($user->uid,$data);  
            $session_data = array(  
                'uid' => $user->uid,  
                'username' => $user->username  
            );  
            $this->session->set_userdata($session_data);  
            redirect('admin/meta');  
       }  
       else  
       {  
            $this->session->set_flashdata('error', '用户名或密码不正确');  
            redirect('admin/login');  
       }  
    }  
}