C#中后台线程和UI线程的交互

在C#中，从Main()方法开始一个默认的线程，一般称之为主线程，如果在这个进行一些非常耗CPU的计算，那么UI界面就会被挂起而处于假死状态，也就是说无法和用户进行交互了，特别是要用类似进度条来实时显示一些提示信息的时候，这种情况就显得很糟糕。如果多开一些线程来完成一些耗时的计算，那么工作线程也是无法如此更新UI界面中的元素的，比如直接显示一个提示信息：label1.Text=outstring，原因很简单UI属于默认的主线程，而线程间是不能这样直接访问彼此的成员的。
如果要解决以上的两个问题，那么可以借助C#中的Delegate和控件类中的Invoke()方法来搞定。
这里给出的例子比较简单，主要思路是：在Main()中启动其它的线程作为后台进程，其中一个线程是实时显示当前的时间，一个线程是显示一些随机数，这样一来三个线程同时运行，彼此通过代理来联系。

using System;

using System.Drawing;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

using System.Threading;

namespace MutliThreadedWinFormsApp

{

public class Form1 : System.Windows.Forms.Form

{

private Thread currentTimeThread = null;

private Thread randomNumbersThread = null;

private System.Windows.Forms.Label label1;

private System.Windows.Forms.TextBox currentTime;

private System.Windows.Forms.Label label2;

private System.Windows.Forms.TextBox randomNumbers;

private System.Windows.Forms.GroupBox threadManager;

private System.Windows.Forms.Button pause;

private System.Windows.Forms.Button stop;

private System.Windows.Forms.Button start;

private System.Windows.Forms.RadioButton manageTime;

private System.Windows.Forms.RadioButton manageNumbers;

private System.Windows.Forms.RadioButton manageBoth;

private System.ComponentModel.Container components = null;

public Form1()

{

InitializeComponent();

//创建新的工作线程

currentTimeThread = new Thread(new ThreadStart(CountTime));

currentTimeThread.IsBackground = true;

randomNumbersThread = new Thread(new ThreadStart(GenerateRandomNumbers));

randomNumbersThread.IsBackground = true;

}

protected override void Dispose( bool disposing )

{

if( disposing )

{

if (components != null)

{

components.Dispose();

}

base.Dispose( disposing );

}

#region UI设计

private void InitializeComponent()

{

this.label1 = new System.Windows.Forms.Label();

this.currentTime = new System.Windows.Forms.TextBox();

this.label2 = new System.Windows.Forms.Label();

this.randomNumbers = new System.Windows.Forms.TextBox();

this.threadManager = new System.Windows.Forms.GroupBox();

this.manageBoth = new System.Windows.Forms.RadioButton();

this.manageNumbers = new System.Windows.Forms.RadioButton();

this.manageTime = new System.Windows.Forms.RadioButton();

this.pause = new System.Windows.Forms.Button();

this.stop = new System.Windows.Forms.Button();

this.start = new System.Windows.Forms.Button();

this.threadManager.SuspendLayout();

this.SuspendLayout();

// label1

this.label1.AutoSize = true;

this.label1.Location = new System.Drawing.Point(8, 24);

this.label1.Name = "label1";

this.label1.Size = new System.Drawing.Size(79, 13);

this.label1.TabIndex = 0;

this.label1.Text = "现在的时间：";

// currentTime

this.currentTime.Location = new System.Drawing.Point(88, 23);

this.currentTime.Name = "currentTime";

this.currentTime.ReadOnly = true;

this.currentTime.Size = new System.Drawing.Size(157, 20);

this.currentTime.TabIndex = 1;

// label2

this.label2.AutoSize = true;

this.label2.Location = new System.Drawing.Point(14, 56);

this.label2.Name = "label2";

this.label2.Size = new System.Drawing.Size(43, 13);

this.label2.TabIndex = 2;

this.label2.Text = "随机数";

// randomNumbers

this.randomNumbers.Location = new System.Drawing.Point(16, 72);

this.randomNumbers.Name = "randomNumbers";

this.randomNumbers.ReadOnly = true;

this.randomNumbers.Size = new System.Drawing.Size(229, 20);

this.randomNumbers.TabIndex = 3;

// threadManager

this.threadManager.Controls.Add(this.manageBoth);

this.threadManager.Controls.Add(this.manageNumbers);

this.threadManager.Controls.Add(this.manageTime);

this.threadManager.Controls.Add(this.pause);

this.threadManager.Controls.Add(this.stop);

this.threadManager.Controls.Add(this.start);

this.threadManager.Location = new System.Drawing.Point(16, 104);

this.threadManager.Name = "threadManager";

this.threadManager.Size = new System.Drawing.Size(229, 154);

this.threadManager.TabIndex = 7;

this.threadManager.TabStop = false;

this.threadManager.Text = "工作线程控制";

// manageBoth

this.manageBoth.Location = new System.Drawing.Point(34, 74);

this.manageBoth.Name = "manageBoth";

this.manageBoth.Size = new System.Drawing.Size(104, 16);

this.manageBoth.TabIndex = 12;

this.manageBoth.Text = "同时运行";

this.manageBoth.CheckedChanged += new System.EventHandler(this.manageBoth_CheckedChanged);

// manageNumbers

this.manageNumbers.Location = new System.Drawing.Point(34, 50);

this.manageNumbers.Name = "manageNumbers";

this.manageNumbers.Size = new System.Drawing.Size(104, 16);

this.manageNumbers.TabIndex = 11;

this.manageNumbers.Text = "更新随机数线程";

this.manageNumbers.CheckedChanged += new System.EventHandler(this.manageNumbers_CheckedChanged);

// manageTime

this.manageTime.Location = new System.Drawing.Point(34, 26);

this.manageTime.Name = "manageTime";

this.manageTime.Size = new System.Drawing.Size(104, 16);

this.manageTime.TabIndex = 10;

this.manageTime.Text = "更新时间线程";

this.manageTime.CheckedChanged += new System.EventHandler(this.manageTime_CheckedChanged);

// pause

this.pause.Location = new System.Drawing.Point(84, 115);

this.pause.Name = "pause";

this.pause.Size = new System.Drawing.Size(54, 23);

this.pause.TabIndex = 9;

this.pause.Text = "暂停";

this.pause.Click += new System.EventHandler(this.pause_Click);

// stop

this.stop.Location = new System.Drawing.Point(158, 115);

this.stop.Name = "stop";

this.stop.Size = new System.Drawing.Size(51, 23);

this.stop.TabIndex = 8;

this.stop.Text = "停止";

this.stop.Click += new System.EventHandler(this.stop_Click);

// start

this.start.Location = new System.Drawing.Point(6, 115);

this.start.Name = "start";

this.start.Size = new System.Drawing.Size(50, 23);

this.start.TabIndex = 7;

this.start.Text = "开始";

this.start.Click += new System.EventHandler(this.start_Click);

// Form1

this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);

this.ClientSize = new System.Drawing.Size(253, 271);

this.Controls.Add(this.threadManager);

this.Controls.Add(this.randomNumbers);

this.Controls.Add(this.label2);

this.Controls.Add(this.currentTime);

this.Controls.Add(this.label1);

this.Name = "Form1";

this.Text = "工作线程和UI的交互";

this.Closing += new System.ComponentModel.CancelEventHandler(this.Form1_Closing);

this.threadManager.ResumeLayout(false);

this.ResumeLayout(false);

this.PerformLayout();

}

#endregion

[STAThread]

static void Main()

{

Application.Run(new Form1());

}

private void start_Click(object sender, System.EventArgs e)

private void stop_Click(object sender, System.EventArgs e)

private void pause_Click(object sender, System.EventArgs e)

private void manageTime_CheckedChanged(object sender, System.EventArgs e)

{

}

private void manageNumbers_CheckedChanged(object sender, System.EventArgs e)

{

}

private void manageBoth_CheckedChanged(object sender, System.EventArgs e)

{

}

/// <summary>

/// 注意其Invoke的使用,其有两种使用形式

/// public void Invoke(System.Delegate delegate);

/// public void Invoke(System.Delegate delegate, object [] args);

/// </summary>

public void CountTime()

{

while(true)

{

Invoke(new UpdateTimeDelegate(updateCurrentTime));

Thread.Sleep(1000);

}

public void GenerateRandomNumbers()

{

int [] randomNumbers = new int[10];

Random r = new Random();

while(true)

{

for(int i = 0; i < randomNumbers.Length; i++)

randomNumbers[i] = r.Next(1, 100);

Invoke(new UpdateRandomNumbers(updateRandomNumbers), new object[] { randomNumbers });

Thread.Sleep(500);

}

/// <summary>

/// 负责更新UI界面中时间显示的函数

/// </summary>

private void updateCurrentTime()

{

currentTime.Text = DateTime.Now.ToLongTimeString();

}

/// <summary>

/// 负责更新UI界面中随机数显示的函数

/// </summary>

/// <param name="numbers"></param>

private void updateRandomNumbers(int [] numbers)

{

System.Text.StringBuilder sb = new System.Text.StringBuilder();

foreach(int i in numbers)

sb.Append(i.ToString()).Append(", ");

randomNumbers.Text = sb.ToString();

}

private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)

{

if( (randomNumbersThread.ThreadState & ThreadState.Running) == ThreadState.Running )

randomNumbersThread.Abort();

randomNumbersThread = null;

if( (currentTimeThread.ThreadState & ThreadState.Running) == ThreadState.Running )

currentTimeThread.Abort();

currentTimeThread = null;

}

public delegate void UpdateTimeDelegate();

public delegate void UpdateRandomNumbers(int [] numbers);

}

其实在C# 2.0 中所有的Control类都有Invoke()方法，如果负责更新UI元素的函数不是定义在Main()中，那么必须首先检测Control类中的InvokeRequired属性。举个例子吧，注意setProgressBarValue()函数中调用自己的方式.
        //在工作线程中更新主窗口进度条
        public void setProgressBarValue(ProgressBar progressBar1,int value)
        {
            if (progressBar1.InvokeRequired)
            {
                object[] parameters = new object[] { value };
                progressBar1.Invoke(new setProgressBarValueDelegate(setProgressBarValue), parameters);
            }
            else
                progressBar1.Value = value;
        }
这里的一些代码参考了http://www.codeproject.com 的例子.

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C#中后台线程和UI线程的交互

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