MSDN上安全调用线程的例子

 这是一个在MSDN中关于安全调用控件线程的例子

  1using System;
  2using System.ComponentModel;
  3using System.Threading;
  4using System.Windows.Forms;
  5
  6namespace CrossThreadDemo
  7{
  8    public partial class Form1 : Form
  9    {
 10        // This delegate enables asynchronous calls for setting
 11        // the text property on a TextBox control.
 12        delegate void SetTextCallback(string text);
 13
 14        // This thread is used to demonstrate both thread-safe and
 15        // unsafe ways to call a Windows Forms control.
 16        private Thread demoThread = null;
 17
 18        // This BackgroundWorker is used to demonstrate the 
 19        // preferred way of performing asynchronous operations.
 20        private BackgroundWorker backgroundWorker1;
 21
 22        private TextBox textBox1;
 23        private Button setTextUnsafeBtn;
 24        private Button setTextSafeBtn;
 25        private Button setTextBackgroundWorkerBtn;
 26
 27        private System.ComponentModel.IContainer components = null;
 28
 29        public Form1()
 30        {
 31            InitializeComponent();
 32        }
 33
 34        protected override void Dispose(bool disposing)
 35        {
 36            if (disposing && (components != null))
 37            {
 38                components.Dispose();
 39            }
 40            base.Dispose(disposing);
 41        }
 42
 43        // This event handler creates a thread that calls a 
 44        // Windows Forms control in an unsafe way.
 45        private void setTextUnsafeBtn_Click(object sender,EventArgs e)
 46        {
 47            this.demoThread = new Thread(new ThreadStart(this.ThreadProcUnsafe));
 48            this.demoThread.Start();
 49        }
 50
 51        // This method is executed on the worker thread and makes
 52        // an unsafe call on the TextBox control.
 53        private void ThreadProcUnsafe()
 54        {
 55            this.textBox1.Text = "This text was set unsafely.";
 56        }
 57
 58        // This event handler creates a thread that calls a 
 59        // Windows Forms control in a thread-safe way.
 60        private void setTextSafeBtn_Click(object sender,EventArgs e)
 61        {
 62            this.demoThread =new Thread(new ThreadStart(this.ThreadProcSafe));
 63            this.demoThread.Start();
 64        }
 65
 66        // This method is executed on the worker thread and makes
 67        // a thread-safe call on the TextBox control.
 68        private void ThreadProcSafe()
 69        {
 70            this.SetText("This text was set safely.");
 71        }
 72
 73        // This method demonstrates a pattern for making thread-safe
 74        // calls on a Windows Forms control. 
 75        //
 76        // If the calling thread is different from the thread that
 77        // created the TextBox control, this method creates a
 78        // SetTextCallback and calls itself asynchronously using the
 79        // Invoke method.
 80        //
 81        // If the calling thread is the same as the thread that created
 82        // the TextBox control, the Text property is set directly. 
 83
 84        private void SetText(string text)
 85        {
 86            // InvokeRequired required compares the thread ID of the
 87            // calling thread to the thread ID of the creating thread.
 88            // If these threads are different, it returns true.
 89            if (this.textBox1.InvokeRequired)
 90            {
 91                SetTextCallback d = new SetTextCallback(SetText);
 92                this.Invoke(d, new object[] { text });
 93            }
 94            else
 95            {
 96                this.textBox1.Text = text;
 97            }
 98        }
 99
        // 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.";
        }

        Windows Form Designer generated code#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());
        }

    }
}