C# 从 .txt 文件中读取更改更新 WPF 应用程序

Question

我对 C# 很陌生，我有一个写入文本文件的程序。我正在尝试编写一些可以在文本文件发生更改时读取该文本文件并在我将打开的 WPF 应用程序中显示文本文件上下文的内容。

我有文件更改侦听器的位，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。

这里是 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向 GUI 确认是时候更新屏幕了。

但是，比这更多的是您使用 FileSystemWatcher 时遇到的错误（即您正在观看 test.ini 但您正在阅读 ShowProgress.ini 中的文件文本并且文件路径丢失）以及您应该尝试的事实以 MVVM 方式学习 WPF。所以，试试我为你做的代码。

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();
    }
}