用C#编写多线程客户端程序

using System;
using System.Drawing;
using System.Threading;
using System.Windows.Forms;
using Microsoft.VisualBasic;
class App {
　// Application entry point 
　public static void Main() {
　　// Run a Windows Forms message loop 
　　Application.Run(new CorrectMultiThreadedForm());
　}
}
// A Form-derived type 
class CorrectMultiThreadedForm : Form{
　// Constructor method 
　public CorrectMultiThreadedForm() {
　　// Create a textbox 
　　text.Location = new Point(10, 10);
　　text.Size = new Size(50, 20);
　　Controls.Add(text);
　　// Create a button 
　　button.Text = "Beep";
　　button.Size = new Size(50, 20);
　　button.Location = new Point(80, 10);
　　// Register Click event handler 
　　button.Click += new EventHandler(OnClick);
　　Controls.Add(button);
　　// Cache a delegate for repeated reuse 
　　enableControls = new BooleanCallback(EnableControls);
　}
　// Method called by the button's Click event 
　void OnClick(Object sender, EventArgs args) {
　　// Get an int from a string 
　　Int32 count = 0;
　　try { count = Int32.Parse(text.Text); } catch (FormatException) {}
　　// Count to that number 
　　EnableControls(false);
　　WaitCallback async = new WaitCallback(Count);
　　ThreadPool.QueueUserWorkItem(async, count);
　}
　// Async method beeps once per second 
　void Count(Object param) {
　　Int32 seconds = (Int32) param;
　　for (Int32 index = 0; index < seconds; index++) {
　　　Interaction.Beep();
　　　Thread.Sleep(1000);
　　}
　　Invoke(enableControls, new Object[]{true});
　}
　void EnableControls(Boolean enable) {
　　button.Enabled = enable;
　　text.Enabled = enable;
　}
　// A delegate type and matching field 
　delegate void BooleanCallback(Boolean enable);
　BooleanCallback enableControls;
　// Some private fields by which to reference controls 
　Button button = new Button();
　TextBox text = new TextBox();
}