如何直接从WPF BackgroundWorker的线程访问UI线程？ [英] How to directly access the UI thread from the BackgroundWorker thread in WPF?

问题描述

我要创建WPF中的备份实用程序，并有关于线程 一般性的问题：

在该方法的 BackgroundWorker的。 DoWork的（），语句Message2.Text =...给出了错误，因为不同的线程拥有它的调用线程不能访问该对象。

有没有办法让我直接访问内backgroundWorker.DoWork（），即改变文本的UI线程在XAML文本框在这一点？或者，我需要所有的显示信息存储在一个内部变量，然后在 backgroundWorker.ProgressChanged显示它（），因为我曾与例如做？percentageFinished

XAML：

  <窗​​口x：类=TestCopyFiles111.Window1
的xmlns =htt​​p://schemas.microsoft.com/winfx/2006/xaml/presentation
的xmlns：X =HTTP：// schemas.microsoft.com/winfx/2006/xaml
标题=窗口1HEIGHT =350WIDTH =525> 
< D​​ockPanel中LastChildFill =真的Horizo​​ntalAlignment =左VerticalAlignment =评出的
保证金=10> 
 
< StackPanel的方向=横向DockPanel.Dock =评出的> 
<按钮X：NAME =Button_Start
的Horizo​​ntalAlignment =左
 DockPanel.Dock =评出的
含量=开始复制
点击= Button_Start_Click
高度=25
保证金=0 0 5 0
 WIDTH =200/> 
<按钮X：NAME =Button_Cancel
的Horizo​​ntalAlignment =左
 DockPanel.Dock =评出的
含量=取消
 =单击 Button_Cancel_Click
高度=25
 WIDTH =200/> 
< / StackPanel的> 
 
<进度X：NAME =进度
 DockPanel.Dock =评出的
的Horizo​​ntalAlignment =左
保证金=0 10 0 0 
高度=23
 WIDTH =405
最短=0
最大=100
 /> 
 
< TextBlock的DockPanel.Dock =评出的X：名称=消息保证金=10 0 0 0/> 
< TextBlock的DockPanel.Dock =评出的X：NAME =CurrentFileCopying保证金=0 10 0 0/> 
< TextBlock的DockPanel.Dock =评出的X：名称=消息2保证金=0 10 0 0/> 
< / DockPanel中> 
< /窗GT; 
  

后台代码：

 使用System.Windows; 
使用System.ComponentModel; 
使用的System.Threading; 
：使用System.IO; 
使用System.Collections.Generic; 
使用系统; 
 
命名空间TestCopyFiles111 
 {
公共部分类窗口1：窗口
 {
私人的BackgroundWorker BackgroundWorker的; 
 
浮动percentageFinished = 0; 
私人INT totalFilesToCopy = 0; 
 INT filesCopied = 0; 
 
串currentPathAndFileName; 
 
私人列表< CopyFileTask> copyFileTasks =新的List< CopyFileTask>（）; 
私有列表<串GT; foldersToCreate =新的List<串GT;（）; 
 
公共窗口1（）
 {
的InitializeComponent（）; 
 Button_Cancel.IsEnabled = FALSE; 
 Button_Start.IsEnabled = TRUE; 
 ProgressBar.Visibility = Visibility.Collapsed; 
 
} 
 
私人无效Button_Start_Click（对象发件人，RoutedEventArgs E）
 {
 Button_Cancel.IsEnabled = TRUE; 
 BackgroundWorker的=新的BackgroundWorker（）; 
 backgroundWorker.WorkerReportsProgress = TRUE; 
 backgroundWorker.WorkerSupportsCancellation = TRUE; 
 ProgressBar.Visibility = Visibility.Visible; 
 
 AddFilesFromFolder（@C：\test，@C：\test2）; 
 
 Message.Text =正在准备拷贝...; 
 
 MakeSureAllDirectoriesExist（）; 
 
 CopyAllFiles（）; 
 
} 
 
 
无效AddFilesFromFolder（字符串sourceFolder，串destFolder）
 {
如果（！Directory.Exists（destFolder））
 Directory.CreateDirectory（destFolder）; 
的String []文件= Directory.GetFiles（sourceFolder）; 
的foreach（在文件中字符串的文件）
 {
字符串名称= Path.GetFileName（文件）; 
串DEST = Path.Combine（destFolder，名）; 
 copyFileTasks.Add（新CopyFileTask（文件，DEST））; 
 totalFilesToCopy ++; 
} 
的String []文件夹= Directory.GetDirectories（sourceFolder）; 
的foreach（在文件夹中的文件夹弦）
 {
字符串名称= Path.GetFileName（文件夹）; 
串DEST = Path.Combine（destFolder，名）; 
 foldersToCreate.Add（DEST）; 
 AddFilesFromFolder（文件夹，DEST）; 
} 
} 
 
无效MakeSureAllDirectoriesExist（）
 {
的foreach（在foldersToCreate VAR folderToCreate）
 {
如果（！ Directory.Exists（folderToCreate））
 Directory.CreateDirectory（folderToCreate）; 
} 
} 
 
无效CopyAllFiles（）
 {
 BackgroundWorker的=新的BackgroundWorker（）; 
 backgroundWorker.WorkerReportsProgress = TRUE; 
 backgroundWorker.WorkerSupportsCancellation = TRUE; 
 
 backgroundWorker.DoWork + =（S，参数）=> 
 {
 filesCopied = 0; 
的foreach（在copyFileTasks VAR copyFileTask）
 {
如果（backgroundWorker.CancellationPending）
 {
 args.Cancel = TRUE; 
的回报; 
} 
 
的DateTime sourceFileLastWriteTime = File.GetLastWriteTime（copyFileTask.SourceFile）; 
的DateTime targetFileLastWriteTime = File.GetLastWriteTime（copyFileTask.TargetFile）; 
 
如果（sourceFileLastWriteTime = targetFileLastWriteTime！）
 {
 Message2.Text =日期是不一样的; 
} 
，否则
 {
 Message2.Text =日期是相同的; 
} 
 
如果
 File.Copy（copyFileTask.SourceFile，copyFileTask.TargetFile）（File.Exists（copyFileTask.TargetFile）！）; 
 
 currentPathAndFileName = copyFileTask.SourceFile; 
 
 UpdatePercentageFinished（）; 
 backgroundWorker.ReportProgress（（INT）percentageFinished）; 
 
 filesCopied ++; 
} 
 
}; 
 
 backgroundWorker.ProgressChanged + =（S，参数）=> 
 {
 percentageFinished = args.ProgressPercentage; 
 ProgressBar.Value = percentageFinished; 
 Message.Text = percentageFinished +说完％; 
 CurrentFileCopying.Text = currentPathAndFileName; 
}; 
 
 backgroundWorker.RunWorkerCompleted + =（S，参数）=> 
 {
 Button_Start.IsEnabled = TRUE; 
 Button_Cancel.IsEnabled = FALSE; 
 ProgressBar.Value = 0; 
 UpdatePercentageFinished（）; 
 CurrentFileCopying.Text =; 
 
如果（percentageFinished< 100）
 {
 Message.Text =的String.Format（取消了在{0：0}％完成，percentageFinished）; 
} 
，否则
 {
 Message.Text =所有文件复制。 
} 
}; 
 
 backgroundWorker.RunWorkerAsync（）; 
} 
 
无效UpdatePercentageFinished（）
 {
 percentageFinished =（filesCopied /（浮点）totalFilesToCopy）* 100F; 
} 
 
 
类CopyFileTask 
 {
公共字符串的SourceFile {搞定;组; } 
公共字符串的TargetFile {搞定;组; } 
公共CopyFileTask（字符串的资源文件，字符串的TargetFile）
 {
的SourceFile =的资源文件; 
的TargetFile =的TargetFile; 
} 
} 
 
私人无效Button_Cancel_Click（对象发件人，RoutedEventArgs E）
 {
 backgroundWorker.CancelAsync（）; 
} 
 
} 
} 
  

解决方案

你有没有看使用Dispatcher.Invoke？

  Dispatcher.Invoke（新动作（（） => {Button_Start.Content = i.ToString（）;}））; 
  

或者，如果你想要的东西异步发生使用的BeginInvoke。

I'm creating a backup utility in WPF and have a general question about threading:

In the method backgroundWorker.DoWork(), the statement Message2.Text = "..." gives the error "The calling thread cannot access this object because a different thread owns it.".

Is there no way for me to directly access the UI thread within backgroundWorker.DoWork(), i.e. change text in a XAML TextBox at that point? Or do I need to store all display information in an internal variable, and then display it in backgroundWorker.ProgressChanged(), as I had to do with e.g. percentageFinished?

XAML:

<Window x:Class="TestCopyFiles111.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1"  Height="350" Width="525">
    <DockPanel LastChildFill="True" HorizontalAlignment="Left" VerticalAlignment="Top"
                Margin="10">

        <StackPanel Orientation="Horizontal" DockPanel.Dock="Top">
            <Button x:Name="Button_Start" 
                    HorizontalAlignment="Left"  
                    DockPanel.Dock="Top" 
                    Content="Start Copying" 
                    Click="Button_Start_Click" 
                    Height="25" 
                    Margin="0 0 5 0"
                    Width="200"/>
            <Button x:Name="Button_Cancel" 
                    HorizontalAlignment="Left"  
                    DockPanel.Dock="Top" 
                    Content="Cancel" 
                    Click="Button_Cancel_Click" 
                    Height="25" 
                    Width="200"/>
        </StackPanel>

        <ProgressBar x:Name="ProgressBar"
                     DockPanel.Dock="Top" 
                     HorizontalAlignment="Left"
                    Margin="0 10 0 0"
                    Height="23"
                     Width="405"
                     Minimum="0"
                     Maximum="100"
                     />

        <TextBlock DockPanel.Dock="Top" x:Name="Message" Margin="0 10 0 0"/>
        <TextBlock DockPanel.Dock="Top" x:Name="CurrentFileCopying" Margin="0 10 0 0"/>
        <TextBlock DockPanel.Dock="Top" x:Name="Message2" Margin="0 10 0 0"/>
    </DockPanel>
</Window>

code-behind:

using System.Windows;
using System.ComponentModel;
using System.Threading;
using System.IO;
using System.Collections.Generic;
using System;

namespace TestCopyFiles111
{
    public partial class Window1 : Window
    {
        private BackgroundWorker backgroundWorker;

        float percentageFinished = 0;
        private int totalFilesToCopy = 0;
        int filesCopied = 0;

        string currentPathAndFileName;

        private List<CopyFileTask> copyFileTasks = new List<CopyFileTask>();
        private List<string> foldersToCreate = new List<string>();

        public Window1()
        {
            InitializeComponent();
            Button_Cancel.IsEnabled = false;
            Button_Start.IsEnabled = true;
            ProgressBar.Visibility = Visibility.Collapsed;

        }

        private void Button_Start_Click(object sender, RoutedEventArgs e)
        {
            Button_Cancel.IsEnabled = true;
            backgroundWorker = new BackgroundWorker();
            backgroundWorker.WorkerReportsProgress = true;
            backgroundWorker.WorkerSupportsCancellation = true;
            ProgressBar.Visibility = Visibility.Visible;

            AddFilesFromFolder(@"c:\test", @"C:\test2");

            Message.Text = "Preparing to copy...";

            MakeSureAllDirectoriesExist();

            CopyAllFiles();

        }


        void AddFilesFromFolder(string sourceFolder, string destFolder)
        {
            if (!Directory.Exists(destFolder))
                Directory.CreateDirectory(destFolder);
            string[] files = Directory.GetFiles(sourceFolder);
            foreach (string file in files)
            {
                string name = Path.GetFileName(file);
                string dest = Path.Combine(destFolder, name);
                copyFileTasks.Add(new CopyFileTask(file, dest));
                totalFilesToCopy++;
            }
            string[] folders = Directory.GetDirectories(sourceFolder);
            foreach (string folder in folders)
            {
                string name = Path.GetFileName(folder);
                string dest = Path.Combine(destFolder, name);
                foldersToCreate.Add(dest);
                AddFilesFromFolder(folder, dest);
            }
        }

        void MakeSureAllDirectoriesExist()
        {
            foreach (var folderToCreate in foldersToCreate)
            {
                if (!Directory.Exists(folderToCreate))
                    Directory.CreateDirectory(folderToCreate);
            }
        }

        void CopyAllFiles()
        {
            backgroundWorker = new BackgroundWorker();
            backgroundWorker.WorkerReportsProgress = true;
            backgroundWorker.WorkerSupportsCancellation = true;

            backgroundWorker.DoWork += (s, args) =>
            {
                filesCopied = 0;
                foreach (var copyFileTask in copyFileTasks)
                {
                    if (backgroundWorker.CancellationPending)
                    {
                        args.Cancel = true;
                        return;
                    }

                    DateTime sourceFileLastWriteTime = File.GetLastWriteTime(copyFileTask.SourceFile);
                    DateTime targetFileLastWriteTime = File.GetLastWriteTime(copyFileTask.TargetFile);

                    if (sourceFileLastWriteTime != targetFileLastWriteTime)
                    {
                        Message2.Text = "dates are not the same";
                    }
                    else
                    {
                        Message2.Text = "dates are the same";
                    }

                    if (!File.Exists(copyFileTask.TargetFile))
                        File.Copy(copyFileTask.SourceFile, copyFileTask.TargetFile);

                    currentPathAndFileName = copyFileTask.SourceFile;

                    UpdatePercentageFinished();
                    backgroundWorker.ReportProgress((int)percentageFinished);

                    filesCopied++;
                }

            };

            backgroundWorker.ProgressChanged += (s, args) =>
            {
                percentageFinished = args.ProgressPercentage;
                ProgressBar.Value = percentageFinished;
                Message.Text = percentageFinished + "% finished";
                CurrentFileCopying.Text = currentPathAndFileName;
            };

            backgroundWorker.RunWorkerCompleted += (s, args) =>
            {
                Button_Start.IsEnabled = true;
                Button_Cancel.IsEnabled = false;
                ProgressBar.Value = 0;
                UpdatePercentageFinished();
                CurrentFileCopying.Text = "";

                if (percentageFinished < 100)
                {
                    Message.Text = String.Format("cancelled at {0:0}% finished", percentageFinished);
                }
                else
                {
                    Message.Text = "All files copied.";
                }
            };

            backgroundWorker.RunWorkerAsync();
        }

        void UpdatePercentageFinished()
        {
            percentageFinished = (filesCopied / (float)totalFilesToCopy) * 100f;
        }


        class CopyFileTask
        {
            public string SourceFile { get; set; }
            public string TargetFile { get; set; }
            public CopyFileTask(string sourceFile, string targetFile)
            {
                SourceFile = sourceFile;
                TargetFile = targetFile;
            }
        }

        private void Button_Cancel_Click(object sender, RoutedEventArgs e)
        {
            backgroundWorker.CancelAsync();
        }

    }
}

解决方案

Have you looked at using Dispatcher.Invoke?

Dispatcher.Invoke(new Action(() => { Button_Start.Content = i.ToString(); }));

Or use BeginInvoke if you want something to happen asynchronously.

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