《WPF编程宝典》一个多线程示例，记录下。

一、介绍：通过多线程特性可使WPF应用程序执行后台工作，同时保持用户界面能够进行响应。1 了解多线程模型 WPF元素具有线程关联性：创建WPF元素的线程拥有所有所创建的元素，其他线程不能直接与这些WPF元素进行交互 dispatcher（调度程序）拥有应用程序线程，并管理工作项队列。当新线程第一次实例化DispatcherObject类的派生类时，会创建调度程序dispatch（WPF坚持一个用户界面线程和一个调度线程）。 ps： a、在传递给BeginInvoke（）的方法中执行耗时的代码是不合理的，如下第2个按钮 sleep（5s）。 b、如果需要暂停异步操作指导用户提供一些反馈信息，可使用Invoke（）方法。 c、BackgroundWorker组件为在单独线程中执行耗时的任务提供一种简单方法，适合单个异步任务后台运行，如算法。.net2.0提供。 d、若在整个应用程序生命周期中运行异步任务，或需与应用程序进行通信时，需要使用.net的线程支持来自定义解决方案。2 代码 主界面xaml

      
         
      
       Text in a text box.
          
      Break the Rules    
      Follow the Rules (with BeginInvoke)        
      Use the BackgroundWorker  
     
    

一种在本调度程序建立异步执行委托：

private void cmdBreakRules_Click(object sender, RoutedEventArgs e)        {            this.Dispatcher.BeginInvoke(new UpdateTextExcute(UpdateTextWrong));            //Thread thread = new Thread(UpdateTextWrong);//报异常            //thread.Start();        }        private void UpdateTextWrong()        {             this.txt.Text = "Here is some new text.";        }

另一种通过在新建的线程上，调用本调度程序dispatch执行委托：

private void cmdFollowRules_Click(object sender, RoutedEventArgs e)        {            Thread thread = new Thread(UpdateTextRight);            thread.Start();        }        private void UpdateTextRight()        {            Thread.Sleep(TimeSpan.FromSeconds(5));                        this.Dispatcher.BeginInvoke(DispatcherPriority.Normal,                (ThreadStart) delegate()                {                    txt.Text = "(5s):Here is some  new text.";                }                );        }

最后一个有关BackgroundWork专用长时间算法的多线程

private void cmdBackgroundWorker_Click(object sender, RoutedEventArgs e)        {            BackgroundWorkerTest test = new BackgroundWorkerTest();            test.ShowDialog();        }

显示另一个窗口

        
           
          
         
           
              
               
               
               
               
             
            
              
               
             
                        
      
       From:
            
      
       1
            
      
       To:
            
      
       500000
            
                  
       Find Primes      
       Cancel      
                  
      
       Results:
            
                  
          
     
    

后台代码：

using System;using System.Windows;using System.ComponentModel;namespace Multithreading{    /// 
    /// Interaction logic for BackgroundWorkerTest.xaml    /// 
    public partial class BackgroundWorkerTest : System.Windows.Window    {        public BackgroundWorkerTest()        {            InitializeComponent();            backgroundWorker = ((BackgroundWorker)this.FindResource("backgroundWorker"));        }        private BackgroundWorker backgroundWorker;        private void cmdFind_Click(object sender, RoutedEventArgs e)        {            // Disable the button and clear previous results.            cmdFind.IsEnabled = false;            cmdCancel.IsEnabled = true;            lstPrimes.Items.Clear();                        // Get the search range.            int from, to;            if (!Int32.TryParse(txtFrom.Text, out from))            {                MessageBox.Show("Invalid From value.");                return;            }            if (!Int32.TryParse(txtTo.Text, out to))            {                MessageBox.Show("Invalid To value.");                return;            }            // Start the search for primes on another thread.            FindPrimesInput input = new FindPrimesInput(from, to);            backgroundWorker.RunWorkerAsync(input);        }        private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)        {            // Get the input values.            FindPrimesInput input = (FindPrimesInput)e.Argument;            // Start the search for primes and wait.            int[] primes = Worker.FindPrimes(input.From, input.To, backgroundWorker);            if (backgroundWorker.CancellationPending)            {                e.Cancel = true;                return;            }            // Return the result.            e.Result = primes;        }        private void backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)        {            if (e.Cancelled)            {                MessageBox.Show("Search cancelled.");            }            else if (e.Error != null)            {                // An error was thrown by the DoWork event handler.                MessageBox.Show(e.Error.Message, "An Error Occurred");            }            else            {                int[] primes = (int[])e.Result;                foreach (int prime in primes)                {                    lstPrimes.Items.Add(prime);                }                            }            cmdFind.IsEnabled = true;            cmdCancel.IsEnabled = false;            progressBar.Value = 0;        }        private void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)        {            progressBar.Value = e.ProgressPercentage;        }        private void cmdCancel_Click(object sender, RoutedEventArgs e)        {            backgroundWorker.CancelAsync();        }    }}

数据类：

public class FindPrimesInput    {                public int To        { get; set; }        public int From        { get; set; }        public FindPrimesInput(int from, int to)        {            To = to;            From = from;        }    }

有关进度条代码：

#region Using directivesusing System;#endregionnamespace Multithreading{    public class Worker    {        public static int[] FindPrimes(int fromNumber, int toNumber)        {            return FindPrimes(fromNumber, toNumber, null);        }        public static int[] FindPrimes(int fromNumber, int toNumber, System.ComponentModel.BackgroundWorker backgroundWorker)        {            int[] list = new int[toNumber - fromNumber];            // Create an array containing all integers between the two specified numbers.            for (int i = 0; i < list.Length; i++)            {                list[i] = fromNumber;                fromNumber += 1;            }            //find out the module for each item in list, divided by each d, where            //d is < or == to sqrt(to)            //if the remainder is 0, the nubmer is a composite, and thus            //we mark its position with 0 in the marks array,            //otherwise the number is a prime, and thus mark it with 1            int maxDiv = (int)Math.Floor(Math.Sqrt(toNumber));            int[] mark = new int[list.Length];            for (int i = 0; i < list.Length; i++)            {                for (int j = 2; j <= maxDiv; j++)                {                    if ((list[i] != j) && (list[i] % j == 0))                    {                        mark[i] = 1;                    }                }                                int iteration = list.Length / 100;                if ((i % iteration == 0) && (backgroundWorker != null))                {                                    if (backgroundWorker.CancellationPending)                    {                        // Return without doing any more work.                        return null;                                          }                    if (backgroundWorker.WorkerReportsProgress)                    {                        //float progress = ((float)(i + 1)) / list.Length * 100;                        backgroundWorker.ReportProgress(i / iteration);                        //(int)Math.Round(progress));                    }                }            }            //create new array that contains only the primes, and return that array            int primes = 0;            for (int i = 0; i < mark.Length; i++)            {                if (mark[i] == 0) primes += 1;            }            int[] ret = new int[primes];            int curs = 0;            for (int i = 0; i < mark.Length; i++)            {                if (mark[i] == 0)                {                    ret[curs] = list[i];                    curs += 1;                }            }            if (backgroundWorker != null && backgroundWorker.WorkerReportsProgress)            {                backgroundWorker.ReportProgress(100);            }            return ret;        }            }}

执行结果：

以上。