UserAccountInfo时间倒计时

界面如下：

代码如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.IO;namespace WeChatTool
{
    public partial class UserAccountInfo : UserControl
    {
        private TimeSpan timespan = new TimeSpan(2, 0, 0);
        private double startTime;
        System.Timers.Timer timer = new System.Timers.Timer();
        public UserAccountInfo()
        {
            InitializeComponent();
            timer.Enabled = true;
            timer.Interval = 1000;
            timer.Stop();
            timer.Elapsed += new System.Timers.ElapsedEventHandler(timer_tick);
        }        private void UserAccountInfo_Load(object sender, EventArgs e)
        {        }
        private void btnProduceToken_Click(object sender, EventArgs e)
        {
            string token = "";
            try
            {
                Uri url = new Uri("https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=wx04ec9a465d7bbaf2&secret=a31fbf89aa42f984bb3f13a8bf5db949");
                HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
                request.Method = "GET";//默认方法是GET
                HttpWebResponse response = request.GetResponse() as HttpWebResponse;
                Stream stream = response.GetResponseStream();
                StreamReader reader = new StreamReader(stream, Encoding.UTF8);
                token = reader.ReadToEnd();
                this.rtbToken.Text = token;
                Properties.Settings.Default.token = token;
                startTime = timespan.TotalSeconds;
                timer.Start();

            }
            catch (ProtocolViolationException ex)
            {
                MessageBox.Show("使用网络协议期间出错时引发的异常！   " + ex.ToString(), "提示信息！", MessageBoxButtons.RetryCancel, MessageBoxIcon.Warning);
                //throw;
            }
        }        private void btnRefresh_Click(object sender, EventArgs e)
        {
            this.timer.Stop();
            this.btnTimer.Text = null;
        }        private void timer_tick(object sender, System.Timers.ElapsedEventArgs e)
        {
            setTimer(startTime);           
        }        public delegate void SetTimer(double timer);
        private void setTimer(double timer)
        {
            if (this.InvokeRequired)
            {
                this.Invoke(new SetTimer(setTimer), timer);
            }
            else
            {
                DateTime datetime = new DateTime(2016,8,18,(int)(timer/3600),(int)((timer/60)%60),(int)((timer/1)%60));
                this.btnTimer.Text = datetime.ToString();
                startTime -= 1;
            }
        }    }
}

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