using System;
  using System.ComponentModel;
  using System.Threading;
  using System.Windows.Forms;

namespace CrossThreadDemo
{
    public partial class Form1 : Form
    {
        //设置这个委托支持异步调用文本框控件的文本属性。
        delegate void SetTextCallback(string text);
        //这个线程用于演示和线程安全的和不安全的方法来调用一个Windows窗体控件。
        private Thread demoThread = null;

        //这个BackgroundWorker用于演示执行异步操作, 推荐使用该方法。
        private BackgroundWorker backgroundWorker1;

        private TextBox textBox1;
        private Button setTextUnsafeBtn;
        private Button setTextSafeBtn;
        private Button setTextBackgroundWorkerBtn;
         
        public Form1()
        {
            InitializeComponent();
        }

        //这个事件处理程序创建一个线程,该线程演示用不安全的方式调用 Windows窗体, 在.net framework2.0后被禁用
        private void setTextUnsafeBtn_Click(object sender,EventArgs e)
        {
            this.demoThread = new Thread(new ThreadStart(this.ThreadProcUnsafe));
            this.demoThread.Start();
        }

   　　//这个方法执行工作线程, 文本框控件不安全的调用, 一执行就会报错.
        private void ThreadProcUnsafe()
        {
            //线程间操作无效: 从不是创建控件“textBox1”的线程访问它。
            this.textBox1.Text = "This text was set unsafely.";
        }
　　　　//这个事件处理程序创建一个线程,该线程使用安全的方式调用 Windows窗体.
        private void setTextSafeBtn_Click(object sender,EventArgs e)
        {
            this.demoThread = new Thread(new ThreadStart(this.ThreadProcSafe));
            this.demoThread.Start();
        }

        //这个方法执行工作线程,使 文本框控件的线程安全的调用.
        private void ThreadProcSafe()
        {
            this.SetText("This text was set safely.");
        }

        //这个方法演示了线程通过安全的模式, 调用一个Windows窗体控件。如果调用线程和当前创建了文本框控件的线程不用,该方法创建一个SetTextCallback,并使用了异步调用自身调用方法,
　　　　//如果调用线程创建的线程是一样的文本框控件,直接设置文本属性。
        private void SetText(string text)
        {
            if (this.textBox1.InvokeRequired)
            {
                SetTextCallback d = new SetTextCallback(SetText);
                this.Invoke(d, new object[] { text });
            }
            else
            {
                //在此设置textBox1的文本
                this.textBox1.Text = text;
            }
        }

        //这个事件处理程序通过调用RunWorkerAsync BackgroundWorker。设置文本框控件的文本属性, 用BackgroundWorker提高RunWorkerCompleted事件。
        private void setTextBackgroundWorkerBtn_Click(object sender,EventArgs e)
        {
            this.backgroundWorker1.RunWorkerAsync();
        }


        //这个事件处理程序设置文本框的文本属性控制。它调用创建的线程文本框控件,所以调用是线程安全的,异步执行BackgroundWorker是首选方法操作.
        private void backgroundWorker1_RunWorkerCompleted(object sender,RunWorkerCompletedEventArgs e)
        {
            this.textBox1.Text ="This text was set safely by BackgroundWorker.";
        } 
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    static class Program
    {
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new CrossThreadDemo.Form1());
        }
    }
}

namespace CrossThreadDemo
{
    partial class Form1
    {
        /// <summary>
        /// 必需的设计器变量。
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// 清理所有正在使用的资源。
        /// </summary>
        /// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows 窗体设计器生成的代码

        /// <summary>
        /// 设计器支持所需的方法 - 不要
        /// 使用代码编辑器修改此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {
            this.textBox1 = new System.Windows.Forms.TextBox();
            this.setTextUnsafeBtn = new System.Windows.Forms.Button();
            this.setTextSafeBtn = new System.Windows.Forms.Button();
            this.setTextBackgroundWorkerBtn = new System.Windows.Forms.Button();
            this.backgroundWorker1 = new System.ComponentModel.BackgroundWorker();
            this.SuspendLayout();
            // 
            // textBox1
            // 
            this.textBox1.Location = new System.Drawing.Point(12, 12);
            this.textBox1.Name = "textBox1";
            this.textBox1.Size = new System.Drawing.Size(240, 21);
            this.textBox1.TabIndex = 0;
            // 
            // setTextUnsafeBtn
            // 
            this.setTextUnsafeBtn.Location = new System.Drawing.Point(15, 55);
            this.setTextUnsafeBtn.Name = "setTextUnsafeBtn";
            this.setTextUnsafeBtn.Size = new System.Drawing.Size(75, 23);
            this.setTextUnsafeBtn.TabIndex = 1;
            this.setTextUnsafeBtn.Text = "Unsafe Call";
            this.setTextUnsafeBtn.Click += new System.EventHandler(this.setTextUnsafeBtn_Click);
            // 
            // setTextSafeBtn
            // 
            this.setTextSafeBtn.Location = new System.Drawing.Point(96, 55);
            this.setTextSafeBtn.Name = "setTextSafeBtn";
            this.setTextSafeBtn.Size = new System.Drawing.Size(75, 23);
            this.setTextSafeBtn.TabIndex = 2;
            this.setTextSafeBtn.Text = "Safe Call";
            this.setTextSafeBtn.Click += new System.EventHandler(this.setTextSafeBtn_Click);
            // 
            // setTextBackgroundWorkerBtn
            // 
            this.setTextBackgroundWorkerBtn.Location = new System.Drawing.Point(177, 55);
            this.setTextBackgroundWorkerBtn.Name = "setTextBackgroundWorkerBtn";
            this.setTextBackgroundWorkerBtn.Size = new System.Drawing.Size(75, 23);
            this.setTextBackgroundWorkerBtn.TabIndex = 3;
            this.setTextBackgroundWorkerBtn.Text = "Safe BW Call";
            this.setTextBackgroundWorkerBtn.Click += new System.EventHandler(this.setTextBackgroundWorkerBtn_Click);
            // 
            // backgroundWorker1
            // 
            this.backgroundWorker1.RunWorkerCompleted += new System.ComponentModel.RunWorkerCompletedEventHandler(this.backgroundWorker1_RunWorkerCompleted);
            // 
            // Form1
            // 
            this.ClientSize = new System.Drawing.Size(268, 96);
            this.Controls.Add(this.setTextBackgroundWorkerBtn);
            this.Controls.Add(this.setTextSafeBtn);
            this.Controls.Add(this.setTextUnsafeBtn);
            this.Controls.Add(this.textBox1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.Load += new System.EventHandler(this.Form1_Load);
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion
    }
}