ProgressBar值正在更改，但是gui在WPF上未更改

在后台线程上进行IO或文件传输是非常糟糕的，因为在文件传输或IO操作期间，CPU没有被使用，因此您的后台线程没有做任何事情，而是在等待IO竞争，并且您浪费了一个线程，这反过来又导致浪费另一个缺点是，即使您在后台线程上进行操作，UI也将无法响应文件传输，而这需要花费大量时间。

我可以继续编写在后台线程上进行IO工作的缺点，但是您应该索取一份有关在.Net中异步进行IO的文档。后台线程用于CPU密集型工作，例如涉及CPU的大量计算。

您应该使用异步IO。使用异步并等待。请阅读有关异步IO的信息。我有一个示例示例，说明您如何使用带有进度栏和响应式UI的纯异步IO进行操作。我明天再写。

**下面是异步io文件传输代码，假定所有文件的大小都相同，以进行进度更新上面提到的代码将起作用，即使在传输文件时移动窗口，应用程序也不会挂起。**

MainWindow.xaml

<Window x:Class="asyncawait.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="514" Width="674">
    <Grid Margin="0,0,0,4">
        <ScrollViewer Name="scrv_Log" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto"  HorizontalAlignment="Left" Width="397" Margin="33,61,0,67">
            <ListBox VirtualizingPanel.VirtualizationMode="Recycling" ItemsSource="{Binding Datas,Mode=OneWay}" Background="White" Foreground="Red"/>
        </ScrollViewer>
        <TextBlock Height="40" Width="70" FontSize="10" Foreground="Green" Text="{Binding FileCounter,Mode=OneWay}" Margin="540,281,56,158"></TextBlock>
        <Button Foreground="Black" IsEnabled="{Binding IsButtonEnabled}" Click="Button_Click"  Height="40" Width="40" RenderTransformOrigin="4.65,0.425" Margin="540,210,86,229"></Button>
        <ProgressBar Value="{Binding Progressvalue,Mode=OneWay}"  Name="prg" Foreground="Green"  Height="20" Width="600" Margin="23,453,44.2,7"></ProgressBar>
        <Label Content="{Binding ElementName=prg,Path=Value}" ContentStringFormat="{}{0}%" Height="25" Margin="253,0,295.2,22"  VerticalContentAlignment="Center" VerticalAlignment="Bottom"/>
        <TextBox Background='AliceBlue' HorizontalAlignment="Left" Height="23" Margin="525,109,0,0" TextWrapping="Wrap"  VerticalAlignment="Top" Width="97"/>
    </Grid>
</Window>

****以下是执行异步IO的代码**

public partial class MainWindow: Window,INotifyPropertyChanged
    {

        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = this;
        }
        public double Progressvalue
        {
            get
            {
                return _Progressvalue;

            } 
            set
            {
                if(value!=_Progressvalue)
                {
                    _Progressvalue=value;
                    OnPropertyChanged();
                }
            }
         }
        private Double _Progressvalue=0;
        private bool _IsEnabled=true;

        public Boolean IsButtonEnabled { 
            get
            {
                return _IsEnabled;
             }

            set
            {
                if(value!=_IsEnabled)
                {
                    _IsEnabled = value;
                    OnPropertyChanged();
                }
            }
        }
        private async  void Button_Click(object sender, RoutedEventArgs e)
        {
            IsButtonEnabled = false;
            await AsyncTransferFiles();
            IsButtonEnabled = true;
            scrv_Log.ScrollToBottom();

        }

        private String fileCounter;
         public String FileCounter
        {
            get
            { return fileCounter; }
            set
            {
                if (value != fileCounter)
                {
                    fileCounter = value;
                    OnPropertyChanged();
                }
            }
        }







        private ObservableCollection<String> _Datas = new ObservableCollection<string>();
        public ObservableCollection<String> Datas
        {
            get
            {
                return _Datas;
            }
        }
         private async Task AsyncTransferFiles()
        {

            var fileNames = Directory.GetFiles("C:\\Data1").ToList();
            int totalCount = fileNames.Count;
            pr = (double)1 / totalCount;
            int counter = 0;
            var progress = new Progress<double>();
            progress.ProgressChanged += (sender, e) =>
                {

                   Progressvalue = Double.Parse(e.ToString());

                };
            foreach (var fileName in fileNames)
            {
                await (CopyFileAsync(fileName, "C:\\GradebookTemp1\\" + fileName.Split('\\')[2], progress, ++counter));
            }
        }



         double pr = 0.0;
         public async Task CopyFileAsync(string sourcePath, string destinationPath,IProgress<double> progress ,int fileCounter)
         {
             using (Stream source = File.Open(sourcePath,FileMode.Open))
             {
                 using (Stream destination = File.Create(destinationPath))
                 {
                     await source.CopyToAsync(destination);
                     progress.Report((int)(pr*fileCounter*100));
                     FileCounter = fileCounter.ToString();
                     Datas.Add("Copied File: " + sourcePath);
                     scrv_Log.ScrollToBottom();

                 }
             }

         }

        private void EnableButton()
        {
            IsButtonEnabled = true;
        }

        private void OnPropertyChanged([CallerMemberName] String propertyName=null)
        {
            var handler = PropertyChanged;
            if(null!=handler)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));

            }
        }

        public event PropertyChangedEventHandler PropertyChanged;
    }