如何：对 Windows 窗体控件进行线程安全调用

// This event handler creates a thread that calls a // Windows Forms control in a thread-safe way.privatevoid setTextSafeBtn_Click(			object sender, 			EventArgs e)		{			this.demoThread = 				new Thread(new ThreadStart(this.ThreadProcSafe));			this.demoThread.Start();		}		// This method is executed on the worker thread and makes// a thread-safe call on the TextBox control.privatevoid ThreadProcSafe()		{			this.SetText("This text was set safely.");		}

// This method demonstrates a pattern for making thread-safe// calls on a Windows Forms control. //// If the calling thread is different from the thread that// created the TextBox control, this method creates a// SetTextCallback and calls itself asynchronously using the// Invoke method.//// If the calling thread is the same as the thread that created// the TextBox control, the Text property is set directly. privatevoid SetText(string text)		{			// InvokeRequired required compares the thread ID of the// calling thread to the thread ID of the creating thread.// If these threads are different, it returns true.if (this.textBox1.InvokeRequired)			{					SetTextCallback d = new SetTextCallback(SetText);				this.Invoke(d, newobject[] { text });			}			else			{				this.textBox1.Text = text;			}		}

// This BackgroundWorker is used to demonstrate the // preferred way of performing asynchronous operations.private BackgroundWorker backgroundWorker1;

// This event handler starts the form's // BackgroundWorker by calling RunWorkerAsync.//// The Text property of the TextBox control is set// when the BackgroundWorker raises the RunWorkerCompleted// event.privatevoid setTextBackgroundWorkerBtn_Click(			object sender, 			EventArgs e)		{			this.backgroundWorker1.RunWorkerAsync();		}				// This event handler sets the Text property of the TextBox// control. It is called on the thread that created the // TextBox control, so the call is thread-safe.//// BackgroundWorker is the preferred way to perform asynchronous// operations.privatevoid backgroundWorker1_RunWorkerCompleted(			object sender, 			RunWorkerCompletedEventArgs e)		{			this.textBox1.Text = 				"This text was set safely by BackgroundWorker.";		}

using System;using System.ComponentModel;using System.Threading;using System.Windows.Forms;namespace CrossThreadDemo{	public class Form1 : Form	{		// This delegate enables asynchronous calls for setting		// the text property on a TextBox control.		delegate void SetTextCallback(string text);		// This thread is used to demonstrate both thread-safe and		// unsafe ways to call a Windows Forms control.		private Thread demoThread = null;		// This BackgroundWorker is used to demonstrate the 		// preferred way of performing asynchronous operations.		private BackgroundWorker backgroundWorker1;		private TextBox textBox1;		private Button setTextUnsafeBtn;		private Button setTextSafeBtn;		private Button setTextBackgroundWorkerBtn;		private System.ComponentModel.IContainer components = null;		public Form1()		{			InitializeComponent();		}		protected override void Dispose(bool disposing)		{			if (disposing && (components != null))			{				components.Dispose();			}			base.Dispose(disposing);		}		// This event handler creates a thread that calls a 		// Windows Forms control in an unsafe way.		private void setTextUnsafeBtn_Click(			object sender, 			EventArgs e)		{			this.demoThread = 				new Thread(new ThreadStart(this.ThreadProcUnsafe));			this.demoThread.Start();		}		// This method is executed on the worker thread and makes		// an unsafe call on the TextBox control.		private void ThreadProcUnsafe()		{			this.textBox1.Text = "This text was set unsafely.";		}		// This event handler creates a thread that calls a 		// Windows Forms control in a thread-safe way.		private void setTextSafeBtn_Click(			object sender, 			EventArgs e)		{			this.demoThread = 				new Thread(new ThreadStart(this.ThreadProcSafe));			this.demoThread.Start();		}		// This method is executed on the worker thread and makes		// a thread-safe call on the TextBox control.		private void ThreadProcSafe()		{			this.SetText("This text was set safely.");		}		// This method demonstrates a pattern for making thread-safe		// calls on a Windows Forms control. 		//		// If the calling thread is different from the thread that		// created the TextBox control, this method creates a		// SetTextCallback and calls itself asynchronously using the		// Invoke method.		//		// If the calling thread is the same as the thread that created		// the TextBox control, the Text property is set directly. 		private void SetText(string text)		{			// InvokeRequired required compares the thread ID of the			// calling thread to the thread ID of the creating thread.			// If these threads are different, it returns true.			if (this.textBox1.InvokeRequired)			{					SetTextCallback d = new SetTextCallback(SetText);				this.Invoke(d, new object[] { text });			}			else			{				this.textBox1.Text = text;			}		}		// This event handler starts the form's 		// BackgroundWorker by calling RunWorkerAsync.		//		// The Text property of the TextBox control is set		// when the BackgroundWorker raises the RunWorkerCompleted		// event.		private void setTextBackgroundWorkerBtn_Click(			object sender, 			EventArgs e)		{			this.backgroundWorker1.RunWorkerAsync();		}				// This event handler sets the Text property of the TextBox		// control. It is called on the thread that created the 		// TextBox control, so the call is thread-safe.		//		// BackgroundWorker is the preferred way to perform asynchronous		// operations.		private void backgroundWorker1_RunWorkerCompleted(			object sender, 			RunWorkerCompletedEventArgs e)		{			this.textBox1.Text = 				"This text was set safely by BackgroundWorker.";		}		#region Windows Form Designer generated code		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, 20);			this.textBox1.TabIndex = 0;			// 			// setTextUnsafeBtn			// 			this.setTextUnsafeBtn.Location = new System.Drawing.Point(15, 55);			this.setTextUnsafeBtn.Name = "setTextUnsafeBtn";			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.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.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.ResumeLayout(false);			this.PerformLayout();		}		#endregion		[STAThread]		static void Main()		{			Application.EnableVisualStyles();			Application.Run(new Form1());		}	}}