private void delButton_Click(object sender, RoutedEventArgs e)
 {
     if (this.dataGrid1.SelectedIndex >= 0)
     {
         role r = this.dataGrid1.SelectedItem as role;
         if (r != null)
         {
             if (UserRole.Del(r))
             {
                 MessageAlert.Alert("删除成功!");
             }
             else
             {
                 MessageAlert.Alert("该条信息不能删除!");
             }
         }
         BindRole();
     }
 }