在 UWP 应用程序关闭时使用来自 TextBox 的数据写入 .txt 文件 [英] Write to a .txt file using data from TextBox when UWP app is closed

问题描述

当用户关闭应用程序时，我相信 App.xaml.cs 中的 OnSuspending 方法在终止之前首先被调用.因此，我将代码放在那里，以便自动将用户在 TextBox 中写入的内容保存到名为 TextFile1.txt 的 .txt 文件中.程序运行时没有错误，但当应用程序关闭时，它不会将用户的数据保存到 .txt 文件中.

When user closes the app, I believe the OnSuspending method in App.xaml.cs is called first before termination. So, I put my code in there in order to automatically save what the user wrote in the TextBox to a .txt file called TextFile1.txt. The program runs without errors but it doesn't save the user's data to the .txt file when app is closed.

App.xaml.cs 中的代码:

Code in App.xaml.cs:

private MainPage mainFrame;

    private async void OnSuspending(object sender, SuspendingEventArgs e)
    {
        var deferral = e.SuspendingOperation.GetDeferral();
        await WriteTextToFile();
        deferral.Complete();
    }

    private async Task WriteTextToFile()
    {
        try
        {
            string text = mainFrame.mainTextBox.Text;
            StorageFile textFile = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///TextFile1.txt"));
            await FileIO.WriteTextAsync(textFile, text);
        }
        catch
        {

        }
    }

MainPage.xaml.cs 中的代码:

Code in MainPage.xaml.cs:

public sealed partial class MainPage : Page
{
        public TextBox mainTextBox => textBox;
        public static MainPage rootPage;
        public MainPage()
        {
            InitializeComponent();
            if (rootPage != null)
            {
                rootPage = this;
            }
        }
}

推荐答案

您的代码失败，因为它尝试写入应用程序的安装文件夹.此文件夹受到保护以确保安装的完整性.

Your code fails because it attempts to write to the app's installation folder. This folder is protected to ensure the integrity of the installation.

要使您的方案发挥作用，请将文本文件写入您的 AppData 位置.https://docs.microsoft.com/en-us/windows/uwp/design/app-settings/store-and-retrieve-app-data

To make your scenario work, write the text file to your AppData location instead. https://docs.microsoft.com/en-us/windows/uwp/design/app-settings/store-and-retrieve-app-data

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