跨线程调用窗体控件

此特别在调节和测量试验时期和平运动转时的少数情状下可信地发生。 在调治以 .NET Framework 2.0 版在此以前的 .NET Framework 编写的应用程序时,大概会并发此丰硕。 大家生硬提议您在发掘此难点时进行修补,但你能够经过将 CheckForIllegalCrossThreadCalls.aspx) 属性设置为 false 来禁止使用它。(不推荐)

.NET Framework 可支持您检验以非线程安全形式访谈控件这一难题。 在调节和测量试验器中运维应用程序时,即使叁个不是创办有些控件的线程的其他线程调用该控件,则调试器会吸引一个 InvalidOperationException.aspx),并出示以下消息:“从不是开创控件控件名称 的线程访谈它。”

对 Windows 窗体控件进行线程安全调用

  1. 询问控件的 InvokeRequired.aspx) 属性。

  2. 如果 InvokeRequired.aspx) 再次来到 true,则动用实际调用控件的嘱托来调用 Invoke.aspx)。

  3. 如果 InvokeRequired.aspx) 重回 false,则一贯调用控件。

  在底下的代码示例中,就要由后台线程奉行的 ThreadProcSafe 方法中贯彻线程安全调用。 若是 TextBox.aspx) 控件的 InvokeRequired.aspx) 再次回到 true,则 ThreadProcSafe 方法会创造 SetTextCallback 的多个实例,并将该实例传递给窗体的 Invoke.aspx) 方法。 这使得 SetText 方法被创制 TextBox.aspx) 控件的线程调用,而且在这里线程上下文少校直接设置 Text.aspx) 属性。

       // 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.");
        }

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());
        }

    }
}

 

 

在未利用 Invoke.aspx) 方法的景观下,从不是创造有些控件的线程的别的线程调用该控件是不安全的。 以下非线程安全的调用的亲自去做。

做客 Windows 窗体控件本质上不是线程安全的。 要是有八个或多个线程操作某一控件的意况,则也许会迫使该控件步向一种不等同的事态。 还恐怕会面世其余与线程相关的 Bug,举例争用状态和死锁。 确定保障以线程安全模式采访控件极其首要。

        // 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.";
        }

什么样:对 Windows 窗体控件举办线程安全调用


本文由金沙电玩城捕鱼发布于手机版下载,转载请注明出处:跨线程调用窗体控件

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