WPF -- 从其他线程中修改更新控件

大家都知道，多线程可以大大提高WPF的反应效率，但是不幸的是，UI控件不能被多个线程同时更改。

比如：

 

public partial class Window1 : Window
{
  public Window1()
  {
    InitializeComponent();

    CheckBox myCheckBox = new CheckBox();
    myCheckBox.Content = "A Checkbox";

    System.Threading.Thread thread = new System.Threading.Thread(
      new System.Threading.ThreadStart(
        delegate()
        {
         txtUpdateDownloadInfo.Text += "update KB  download begin...." + Environment.NewLine；
        }
    ));

    thread.Start();
  }
}

 

则会抛出： The calling thread cannot access this object because a different thread owns it.的异常。

 

在Winform中我们可以是设置： Control.CheckForIllegalCrossThreadCalls = false; 在加上lock可以解决此问题，但是WPF中是没有这个属性的。

而幸运的是WPF同样提供了一个功能更大---Dispatcher。在WPF中大多数控件都是继承于DispacterObject，所以他们都具有Dispatcher属性。

所以，解决方案：

WPF：

 

  private void btnDownload_Click(object sender, RoutedEventArgs e)
        {
            if (string.IsNullOrEmpty(txtUpdates.Text))
            {
                MessageBox.Show("Error, Please input the update KBNumber");
                return;
            }
            try
            {
                string[] updates = txtUpdates.Text.Split(new char[] { ' ', '\t', '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries);
                foreach (var item in updates)
                {
                    ParameterizedThreadStart st = new ParameterizedThreadStart(Download);
                    Thread t = new Thread(st);
                    t.Start(item);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error with :" + ex.Message);
            }
        }
        public void Download(object Kbnumber)
        {
            CopyUpdates(Kbnumber as string);
        }
        private void CopyUpdates(string p_updates)
        {
           Application.Current.Dispatcher.BeginInvoke(
  DispatcherPriority.Background,
  new Action(() => txtUpdateDownloadInfo.Text += "update KB" + p_updates + " download begin...." + Environment.NewLine));
                        
                      
                        IEnumerable<KeyValuePair<string, string>> updateLocations = new Dictionary<string, string>();

                        updateLocations = updateLocations.Union(UpdatesSupport.GetUpdateSource(p_updates));

                        foreach (KeyValuePair<string, string> kvp in updateLocations)
                        {
                            try
                            {
                                if (!IO.Directory.Exists(IO.Path.GetDirectoryName(kvp.Value)))
                                    IO.Directory.CreateDirectory(IO.Path.GetDirectoryName(kvp.Value));

                                if (!IO.File.Exists(kvp.Value) || IO.File.GetLastWriteTimeUtc(kvp.Value) < IO.File.GetLastWriteTimeUtc(kvp.Key))
                                    IO.File.Copy(kvp.Key, kvp.Value);
                            }
                            catch
                            { }
                        }

                        Application.Current.Dispatcher.BeginInvoke(
             DispatcherPriority.Background,
             new Action(() => txtUpdateDownloadInfo.Text += "update KB" + p_updates + " download completed...." + Environment.NewLine));

            
        }       

 

Winform：

 

 

 public UpdateInfos()
        {
            InitializeComponent();

            DownloadPanel dp = new DownloadPanel();
            dp.Location = new Point(9, 19);
            gbxUIODT.Controls.Add(dp);
            
            Control.CheckForIllegalCrossThreadCalls = false;
        }

        private void btnUIDownload_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(txtUIUpdates.Text))
            {
                MessageBox.Show("Error, Please input the update KBNumber");
                return;
            }
            try
            {
                string[] updates = txtUIUpdates.Text.Split(new char[] { ' ', '\t', '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries);
                foreach (var item in updates)
                {
                    ParameterizedThreadStart st = new ParameterizedThreadStart(Download);
                    Thread t = new Thread(st);
                    t.Start(item);
                }
            }
            catch(Exception ex)
            {
                MessageBox.Show("Error with :" + ex.Message);
            }

        }

        public void Download(object Kbnumber)
        {    
            CopyUpdates(Kbnumber as string);  
        }
  public  void CopyUpdates(string p_updates)
        {
            lock (this)
            {
                txtUIDonwloadInfo.Text += "update KB" + p_updates + " download begin...." + Environment.NewLine;
            }
            IEnumerable<KeyValuePair<string, string>> updateLocations = new Dictionary<string, string>();
           
            updateLocations = updateLocations.Union(GetUpdateSource(p_updates));

            foreach (KeyValuePair<string, string> kvp in updateLocations)
            {
                try
                {
                    if (!Directory.Exists(Path.GetDirectoryName(kvp.Value)))
                        Directory.CreateDirectory(Path.GetDirectoryName(kvp.Value));

                    if (!File.Exists(kvp.Value) || File.GetLastWriteTimeUtc(kvp.Value) < File.GetLastWriteTimeUtc(kvp.Key))
                        File.Copy(kvp.Key, kvp.Value);
                }
                catch
                { }
            }
            lock (this)
            {
                txtUIDonwloadInfo.Text += "update KB" + p_updates + " download completed...." + Environment.NewLine;
            }
        }