Question

我是WP8上的新手并尝试构建一个应用程序，该应用程序从XML文件中读取常量变量并将用户更改写入另一个xml文件。

但是，我无法使用以下代码创建文件夹或文件。

    public MainPage()
    {
        this.InitializeComponent();

        this.NavigationCacheMode = NavigationCacheMode.Required;

        this.writeFile();

    }

    public async void writeFile()
    {
        XDocument xDoc = XDocument.Load("Values.xml");
        lblSafakCount.Text = xDoc.Descendants("isFirstUse").FirstOrDefault().Value.ToString();

        string input = @"<isFirstUse>NO</isFirstUse>";
        var replacement = XElement.Parse(input);;

        byte[] bytes = System.Text.Encoding.UTF8.GetBytes(input);
        StorageFolder local = ApplicationData.Current.LocalFolder;
        if (local != null)
        {
            StorageFolder sf = await local.CreateFolderAsync("Res", CreationCollisionOption.ReplaceExisting);
            StorageFile file = await sf.CreateFileAsync("val.xml", CreationCollisionOption.OpenIfExists);
            using (var stream = await file.OpenStreamForWriteAsync())
            {
                stream.Seek(0, SeekOrigin.End);
                stream.Write(bytes, 0, bytes.Length);
            }
        }

    }

我已成功读取Values.xml中的isFirstUse参数，因此从文件读取时没有问题。当我尝试逐步检查代码时，app在测试期间不会抛出任何错误，但不会创建文件夹或文件。

你能帮帮忙吗？感谢。

Answer 1

以下是根据您的功能进行的读写操作

如果您想写入SD卡，可以在此处找到更多信息 Access the SD card in Windows Phone

public async void MyWriteFile()
{
    string input = @"<isFirstUse>NO</isFirstUse>";

    byte[] bytes = System.Text.Encoding.UTF8.GetBytes(input);

    StorageFolder local = ApplicationData.Current.LocalFolder;
    if (local != null)
    {
        StorageFolder sf = await local.CreateFolderAsync("Res", CreationCollisionOption.ReplaceExisting);
        StorageFile file = await sf.CreateFileAsync("val.xml", CreationCollisionOption.OpenIfExists);
        using (var stream = await file.OpenStreamForWriteAsync())
        {
            stream.Seek(0, SeekOrigin.End);
            stream.Write(bytes, 0, bytes.Length);
        }
    }

}

private async void MyReadFile()
{
    byte[] bytes = new byte[256];
    StorageFolder local = ApplicationData.Current.LocalFolder;
    if (local != null)
    {
        StorageFolder sf = await local.CreateFolderAsync("Res", CreationCollisionOption.OpenIfExists);
        StorageFile file = await sf.CreateFileAsync("val.xml", CreationCollisionOption.OpenIfExists);
        using (var stream = await file.OpenStreamForReadAsync())
        {
            stream.Read(bytes, 0, 256);
        }
    }
}

在WP8中创建文件和文件夹

1 个答案: