C＃从.txt文件读取更改更新WPF应用程序

Question

我是C＃的新手，我有一个写入文本文件的程序。 我正在尝试编写一些东西，当它发生更改时可以读取该文本文件，并在我应该打开的WPF应用程序中显示该文本文件conext。

我对文件更改侦听器有所了解，我知道如何读取文件文本。 我不知道如何用文本更新WPF表单上的文本块。

这是XAML

    <Window x:Class="ShowProgressBox.MainWindow"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            Title="MainWindow" 
            Height="75" 
            Width="225" 
            ResizeMode="NoResize" 
            MouseLeftButtonDown="Window_MouseLeftButtonDown"
            WindowStyle="None"
            BorderBrush="Black"
            BorderThickness="5"
            AllowsTransparency="True"

            ToolTip="Activate window and press [ESC] key to close."
            >
        <Grid Margin="0,0,-10,0" IsManipulationEnabled="True" Focusable="True" >
            <TextBlock HorizontalAlignment="Center" FontSize="15" Margin="54,0,50,43" Width="121" FontFamily="Lucida Sans" ><Run FontWeight="Bold" Text="Macro Progress"/></TextBlock>
            <Image Source="C:\Users\Desktop\code-512.png" HorizontalAlignment="Left" Height="44" VerticalAlignment="Top" Width="54" RenderTransformOrigin="0.494,0.484"/>
            <TextBlock HorizontalAlignment="Center" Margin="46,22,20,0" TextWrapping="Wrap" Text="{Binding FileText}" VerticalAlignment="Top" Height="33" Width="159"/>
        </Grid>
    </Window>

后面的代码如下所示：

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    using System.Windows;
    using System.Windows.Controls;
    using System.Windows.Data;
    using System.Windows.Documents;
    using System.Windows.Input;
    using System.Windows.Media;
    using System.Windows.Media.Imaging;
    using System.Windows.Navigation;
    using System.Windows.Shapes;
    using System.Security.Permissions;
    using System.IO;
    using System.Security.Permissions;


    namespace ShowProgressBox
    {
        /// <summary>
        /// Interaction logic for MainWindow.xaml
        /// </summary>
        public partial class MainWindow : Window
        {
            public string FileText { get; set; }

            public MainWindow()
            {
                InitializeComponent();
                this.Topmost = true;
                this.ShowInTaskbar = false;
                this.Top = 10;
                this.Left = 10;
                this.PreviewKeyDown += new KeyEventHandler(HandleEsc);
                RunWatch();
            }

            private void Window_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
            {
                this.DragMove();
            }

            private void HandleEsc(object sender, KeyEventArgs e)
            {
                if (e.Key == Key.Escape)
                {
                    Close();
                }
            }

            [PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
            public static void RunWatch()
            {
                FileSystemWatcher watcher = new FileSystemWatcher();

                // Watch for changes in LastAccess and LastWrite times, and the renaming of files or directories. 
                watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName;
                // FILE TO WATCH PATH AND NAME. 
                watcher.Path = @"C:\Users\Desktop\";
                watcher.Filter = "test.ini";
                // Add event handlers.
                watcher.Changed += new FileSystemEventHandler(OnChanged);
                watcher.Created += new FileSystemEventHandler(OnChanged);
                watcher.Deleted += new FileSystemEventHandler(OnChanged);
                watcher.Renamed += new RenamedEventHandler(OnRenamed);
                // Begin watching.
                watcher.EnableRaisingEvents = true;
            }

            // Define the event handlers. 
            private static void OnChanged(object source, FileSystemEventArgs e)
            {
                //THE FILE CHANGED NOW LET'S UPDATE THE TEXT.

                string Text;

                try
                {
                    //Read file update the Graphical User Interface 
                   FileText = File.ReadAllText("ShowProgress.ini");

                }
                catch (System.IO.FileNotFoundException)
                {
                    FileText = "File not found.";
                }
                catch (System.IO.FileLoadException)
                {
                    FileText = "File Failed to load";
                }
                catch (System.IO.IOException)
                {
                    FileText = "File I/O Error";
                }
                catch (Exception err)
                {
                    FileText = err.Message;
                }
            }

            private static void OnRenamed(object source, RenamedEventArgs e)
            {
                // There will be code here to re-create file if it is renamed
            }
        }
    }

Answer 1

简而言之，您所缺少的只是引发PropertyChanged事件。 这就是绑定目标如何确认GUI到了该更新屏幕的时候了。

但是，更多的是您使用FileSystemWatcher时遇到的错误（即，您正在看test.ini，但是您正在ShowProgress.ini中读取文件文本，并且文件路径丢失了），以及您应该尝试学习WPF的事实以MVVM方式。 因此，请尝试为您执行的代码。

public class MainViewModel : ViewModelBase
{
    private readonly string pathToWatch;
    private const string FileToWatch = "test.ini";

    private string fileText;
    public string FileText
    {
        get { return fileText; }
        set
        {
            if (fileText == value) return;
            fileText = value;
            OnPropertyChanged();
        }
    }

    public MainViewModel()
    {
        pathToWatch = Environment.GetEnvironmentVariable("UserProfile") + @"\DeskTop\";

        RunWatch();
    }

    public void RunWatch()
    {
        var watcher = new FileSystemWatcher();

        // Watch for changes in LastAccess and LastWrite times, and the renaming of files or directories. 
        watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName;
        // FILE TO WATCH PATH AND NAME. 
        watcher.Path = pathToWatch;
        watcher.Filter = FileToWatch;
        // Add event handlers.
        watcher.Changed += OnChanged;
        watcher.Created += OnChanged;
        watcher.Deleted += OnChanged;
        watcher.Renamed += OnRenamed;
        // Begin watching.
        watcher.EnableRaisingEvents = true;
    }

    // Define the event handlers. 
    private void OnChanged(object source, FileSystemEventArgs e)
    {
        //THE FILE CHANGED NOW LET'S UPDATE THE TEXT.

        try
        {
            //Read file update the Graphical User Interface 
            FileText = File.ReadAllText(pathToWatch + FileToWatch);
        }
        catch (FileNotFoundException)
        {
            FileText = "File not found.";
        }
        catch (FileLoadException)
        {
            FileText = "File Failed to load";
        }
        catch (IOException)
        {
            FileText = "File I/O Error";
        }
        catch (Exception err)
        {
            FileText = err.Message;
        }
    }

    private static void OnRenamed(object source, RenamedEventArgs e)
    {
        // There will be code here to re-create file if it is renamed
    }

public abstract class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    [NotifyPropertyChangedInvocator]
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        var handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
}

public partial class MainWindow
{
    public MainWindow()
    {
        InitializeComponent();
        DataContext = new MainViewModel();
    }
}