这篇博客将梳理一下.NET中4个Timer类，及其用法。
1. System.Threading.Timer
public Timer(TimerCallback callback, object state, int dueTime, int period);
callback委托将会在period时间间隔内重复执行，state参数可以传入想在callback委托中处理的对象，dueTime标识多久后callback开始执行，period标识多久执行一次callback。
using System.Threading;
// System.Threading.Timer
Timer timer = new Timer(delegate
{
Console.WriteLine($"Timer Thread: {Thread.CurrentThread.ManagedThreadId}");
Console.WriteLine($"Is Thread Pool: {Thread.CurrentThread.IsThreadPoolThread}");
Console.WriteLine("Timer Action.");
},
null,
2000,
1000
);
Console.WriteLine("Main Action.");
Console.WriteLine($"Main Thread: {Thread.CurrentThread.ManagedThreadId}");
Console.ReadLine();
Timer回掉方法执行是在另外ThreadPool中一条新线程中执行的。
2. System.Timers.Timer
System.Timers.Timer和System.Threading.Timer相比，提供了更多的属性，
Interval 指定执行Elapsed事件的时间间隔；
Elapsed 指定定期执行的事件；
Enabled 用于Start/Stop Timer；
Start 开启Timer
Stop 停止Timer
System.Timers.Timer timer = new System.Timers.Timer();
timer.Interval = 500;
timer.Elapsed += delegate
{
Console.WriteLine($"Timer Thread: {Thread.CurrentThread.ManagedThreadId}");
Console.WriteLine($"Is Thread Pool: {Thread.CurrentThread.IsThreadPoolThread}");
Console.WriteLine("Timer Action");
timer.Stop();
};
timer.Start();
Console.WriteLine("Main Action.");
Console.WriteLine($"Main Thread: {Thread.CurrentThread.ManagedThreadId}");
Console.ReadLine();
Timer Elapsed定期任务是在ThreadPool的线程中执行的。
3. System.Windows.Forms.Timer
Interval 指定执行Elapsed事件的时间间隔；
Tick 指定定期执行的事件；
Enabled 用于Start/Stop Timer；
Start 开启Timer
Stop 停止Timer
使用System.Windows.Forms.Timer来更新窗体中Label内时间，
using System.Windows.Forms;
public Form1()
{
InitializeComponent();
this.Load += delegate
{
Timer timer = new Timer();
timer.Interval = 500;
timer.Tick += delegate
{
System.Diagnostics.Debug.WriteLine($"Timer Thread: {System.Threading.Thread.CurrentThread.ManagedThreadId}");
System.Diagnostics.Debug.WriteLine($"Is Thread Pool: {System.Threading.Thread.CurrentThread.IsThreadPoolThread}");
this.lblTimer.Text = DateTime.Now.ToLongTimeString();
};
timer.Start();
System.Diagnostics.Debug.WriteLine($"Main Thread: {System.Threading.Thread.CurrentThread.ManagedThreadId}");
};
}
