多线程

1，Windows窗体控件不是线程安全的，如果多个线程操控WindowGUI组件，结果可能不正确。为了保证线程以线程安全的方式操控GUI组件，与GUI组件的所有交互都要由用户界面线程（UI线程）来执行，即创建和维护GUI的线程。Control类提供Invoke方法可以帮助这个过程。

2，Form1设计窗体：

3，Form1.cs 代码：

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.Threading;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private Class1 letter1;
        private Class1 letter2;
        private Class1 letter3;

        private void Form1_Load(object sender, EventArgs e)
        {
            letter1 = new Class1(label1);
            Thread firstThread = new Thread(new ThreadStart(letter1.GenerateRandomCharacters));
            firstThread.Name = "Thread 1";
            firstThread.Start();

            letter2 = new Class1(label2);
            Thread secondThread = new Thread(new ThreadStart(letter2.GenerateRandomCharacters));
            secondThread.Name = "Thread 2";
            secondThread.Start();

            letter3 = new Class1(label3);
            Thread thirdThread = new Thread(new ThreadStart(letter3.GenerateRandomCharacters));
            thirdThread.Name = "Thread 3";
            thirdThread.Start();

        }

        private void Form1_FormClosed(object sender, FormClosedEventArgs e)
        {
            System.Environment.Exit(System.Environment.ExitCode);
        }

        private void threadCheckBox_CheckedChanged(object sender, EventArgs e)
        {
            if (sender == checkBox1)
                letter1.Toggle();
            else if (sender == checkBox2)
                letter2.Toggle();
            else if (sender == checkBox3)
                letter3.Toggle();
        }

    }
}

3，Class1.cs 代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Windows.Forms;
using System.Drawing;

namespace WindowsFormsApplication1
{
    class Class1
    {
        private static Random generator = new Random();
        private bool suspended = false;
        private Label output;
        private string threadName;

        public Class1(Label label)
        {
            output = label;
        }

        private delegate void DisplayDelegate(char displayChar);

        private void DisplayCharacter(char displayChar)
        {
            output.Text = threadName + ":" + displayChar;
        }

        public void GenerateRandomCharacters()
        {
            threadName = Thread.CurrentThread.Name;
            while (true)
            {
                Thread.Sleep(generator.Next(1001));
                lock (this)
                {
                    while (suspended)
                    {
                        Monitor.Wait(this);
                    }
                }
                char displayChar = (char)(generator.Next(26) + 65);
                output.Invoke(new DisplayDelegate(DisplayCharacter), new object[] { displayChar });
            }
        }
        public void Toggle()
        {
            suspended = !suspended;
            output.BackColor = suspended ? Color.Red : Color.LightGreen;
            lock (this)
            {
                if (!suspended)
                {
                    Monitor.Pulse(this);
                }
            }
        }
    }
}

4，运行结果：可以看到3个线程分别更新Label的随机字母，点ComboBox随时暂停。

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