C#学习教程：在Console中工作但在Windows窗体中不工作的异步代码分享

我正在尝试编写一个不断在局域网上搜索主机的应用程序。 当我将此作为控制台运行时，countdown.Wait（）似乎工作正常。 但是，当我将代码带入windows窗体时，countdown.Signal（）似乎没有减少它的计数器。 不确定是什么问题。

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Net.NetworkInformation; using System.Diagnostics; using System.Net; using System.Threading; namespace Multi_Threaded { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { PortScanner ps = new PortScanner(); ps.ProbeCompleted += new PingProbeCompleted(ps_ProbeCompleted); ps.run_ping_probe(); } void ps_ProbeCompleted(object sender, PingProbeCompletedArguments e) { MessageBox.Show("I found " + e.ip_adresses_list_of_host.Count.ToString() + "host(s)"); } } public delegate void PingProbeCompleted(object sender,PingProbeCompletedArguments e); public class PingProbeCompletedArguments : EventArgs { public List ip_adresses_list_of_host; } public class PortScanner { public event PingProbeCompleted ProbeCompleted; static List ip_adresses = new List(); static CountdownEvent countdown; public void run_ping_probe() { ip_adresses.Clear(); countdown = new CountdownEvent(1); string ipBase = "10.125."; for (int sub = 0; sub <14; sub++) { for (int i = 1; i <255; i++) { string ip = ipBase + sub.ToString() + "." + i.ToString(); Ping p = new Ping(); p.PingCompleted += new PingCompletedEventHandler(p_PingCompleted); countdown.AddCount(); p.SendAsync(ip, 100, ip); } } countdown.Signal(); countdown.Wait(); PingProbeCompletedArguments e = new PingProbeCompletedArguments(); e.ip_adresses_list_of_host = ip_adresses; ProbeCompleted(this, e); } private void p_PingCompleted(object sender, PingCompletedEventArgs e) { string ip = (string)e.UserState; if (e.Reply.Status == IPStatus.Success) { ip_adresses.Add(ip + "t" + e.Reply.RoundtripTime + " ms"); } countdown.Signal(); } } 

  private void Form1_Load(object sender, EventArgs e) { PortScanner ps = new PortScanner(); ps.ProbeCompleted += new PingProbeCompleted(ps_ProbeCompleted); ThreadPool.QueueUserWorkItem((w) => ps.run_ping_probe()); }