/// <summary>
/// 关闭需确认
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Form1_Closing(object sender, FormClosingEventArgs e)
{
    if (MessageBox.Show("是否确认退出程序？", "退出", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
    {
        //关闭所有的线程
        this.Dispose();
        this.Close();
    }
    else
    {
        e.Cancel = true;
    }
}