两者区别是 Timer在非UI线程跑的，DispatcherTimer是在UI线程跑的，
DispatcherTimer 可以直接更新UI
Timer必须使用this.Dispatcher.BeginInvoke去更新UI
private void DisPatcherTimerMethod()
{
DispatcherTimer timer = new DispatcherTimer();
timer.Interval = TimeSpan.FromMilliseconds(1000);
timer.Tick += Timer_Tick;
timer.Start();
}
private void Timer_Tick(object sender, EventArgs e)
{
this.label1.Text = DateTime.Now.ToString();
}
private void TimerMethod()
{
System.Timers.Timer tmr = new System.Timers.Timer(1000); //1秒一个循环
tmr.Elapsed += tmr_Elapsed;
tmr.Start();
}
private void tmr_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
this.Dispatcher.BeginInvoke(new Action(() =>
{
this.label2.Text = DateTime.Now.ToString();
}), null);
}