/**
  * 注册处理
  */
 public function do_register()
 {
     $username = I('username');
     $password = I('password');
     $repassword = I('repassword');
     if (empty($username)) {
         $this->error('用户名不能为空');
     }
     if (empty($password)) {
         $this->error('密码不能为空');
     }
     if ($password != $repassword) {
         $this->error('确认密码错误');
     }
     //检测用户是否已注册
     $model = new Model('User');
     $user = $model->where(array('username' => $username))->find();
     if (!empty($user)) {
         $this->error('用户名已存在');
     }
     $data = array('username' => $username, 'password' => md5($password), 'created_at' => time());
     if (!($model->create($data) && $model->add())) {
         $this->error('注册失败!' . $model->getDbError());
     }
     $this->success('注册成功,请登录', U('login'));
 }