/// <summary>
/// 得到一个窗体对象，如果被销毁，则另创
/// </summary>
/// <returns>返回RegisterForm对象</returns>
public static RegisterForm getRegisterForm()
{
if (rform.IsDisposed) // 如果窗体被销毁，直接另创一个窗体
{
rform = new RegisterForm();
}
return(rform);
}
/// <summary>
/// 点击注册，弹出注册框
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void BtnReg_Click(object sender, EventArgs e)
{
RegisterForm rForm = RegisterForm.getRegisterForm();
rForm.Show();
}