.NET提供了哪几个定时器类型

ThreadTimer timer=new Timer(new TimerCallback(ThreadTimerHandler),null,Timeout.Infinite,Timeout.Infinite,ThreadTimer.Change(INTERVAL,INTERVAL));

using System.Windows.Forms;
using System;

namespace WindowsFormsApplication1
{
    
    public partial class Timers : Form
    {
        private const int INTERVAL = 1000;//1 second
        private System.Timers.Timer timersTimer = new System.Timers.Timer(INTERVAL);
        private System.Threading.Timer threadTimer = null;
        //这个委托用来在工作者线程中访问UI线程中创建的控件
        private delegate void OutputDelegate(DateTime time);
        public Timers()
        {
            InitializeComponent();
        }

        /// <summary>
        /// 启动定时器
        /// </summary>
        private void Start_Click(object sender, EventArgs e)
        { 
            //先保证所有的定时器停止
            WindowsFormsTimerStop();
            TimersTimerStop();
            ThreadTimerStop();

            if (FormsTimer.Checked)
            {
                WindowsFormsTimerStart();
            }
            else if (SystemTimersTimer.Checked)
            {
                TimersTimerStart();
            }
            else
            {
                ThreadTimerStart();
            }

        }

        /// <summary>
        /// 使当前线程休眠一段时间
        /// </summary>
        private void Sleep_Click(object sender, EventArgs e)
        { 
            //睡眠5 second
            outPut.Text += "现在开始睡眠5秒";
            System.Threading.Thread.Sleep(5 * 1000);
        }

        /// <summary>
        /// 停止所有定时器
        /// </summary>
        private void Stop_Click(object sender, EventArgs e)
        { 
            //保证所有定时停止
            WindowsFormsTimerStop();
            TimersTimerStop();
            ThreadTimerStop();
        }

        /// <summary>
        /// 清空输出
        /// </summary>
        private void Reset_Click(object sender, EventArgs e)
        {
            outPut.Text = string.Empty;
        }

        #region 三个定时器的启动与停止

        /// <summary>
        /// 启动Windows.Forms.Timer定时器
        /// </summary>
        private void WindowsFormsTimerStart()
        {
            WindowsFormsTimer.Interval = INTERVAL;
            WindowsFormsTimer.Tick += TimerHandler;
            WindowsFormsTimer.Start();
        }

        /// <summary>
        /// 停止Windows.Forms.Timer定时器
        /// </summary>
        private void WindowsFormsTimerStop()
        {
            WindowsFormsTimer.Stop();
        }



        /// <summary>
        /// 启动Timers.Timer定时器
        /// </summary>
        private void TimersTimerStart()
        {
            timersTimer.Elapsed += TimerHandler;
            //把当前窗体控件赋给Timers.Timer的同步对象属性，
            //以保证其回调方法能访问当前UI线程的控件
            timersTimer.SynchronizingObject = this;
            timersTimer.Start();
        }

        /// <summary>
        /// 停止Timers.Timer定时器
        /// </summary>
        private void TimersTimerStop()
        {
            timersTimer.Stop();
        }

        /// <summary>
        /// 启动Threading.Timer定时器
        /// 当初始化结束后该定时器就立即启动
        /// </summary>
        private void ThreadTimerStart()
        {
            threadTimer = new System.Threading.Timer(new System.Threading.TimerCallback(ThreadTimerHandler), null, System.Threading.Timeout.Infinite, System.Threading.Timeout.Infinite);
            threadTimer.Change(INTERVAL, INTERVAL);
        }

        /// <summary>
        /// 如果Threading.Timer没有停止，则停止
        /// 这里停止使用的是把间隔时间设置为无限大
        /// Threading.Timer接口和其他两个定时器类型略有不同
        /// </summary>
        private void ThreadTimerStop()
        {
            if (threadTimer != null)
            {
                threadTimer.Change(System.Threading.Timeout.Infinite, System.Threading.Timeout.Infinite);
            }
        }

        #endregion

        #region 回调方法及其他

        /// <summary>
        /// 实际执行Threading.Timer的方法
        /// </summary>
        /// <param name="time"></param>
        private void ThreadTimerHandlerUI(DateTime time)
        {
            outPut.Text += time.ToString() + "System.Threading.Timer到时了\r\n";
        }

        /// <summary>
        /// Threading.Timer的回调方法，需要使用BeginInvoke方法来访问UI线程中的控件
        /// </summary>
        /// <param name="state">状态参数</param>
        private void ThreadTimerHandler(object state)
        {
            BeginInvoke(new OutputDelegate(ThreadTimerHandlerUI), DateTime.Now);
        }

        /// <summary>
        /// 回调方法
        /// </summary>
        /// <param name="sender">事件发送者</param>
        /// <param name="e">事件参数</param>
        private void TimerHandler(object sender, EventArgs e)
        {
            outPut.Text += DateTime.Now.ToString() + sender.ToString() + "到时了\r\n";
        }

        #endregion
    }

    
}