覆盖 wp8 中的现有文件 [英] Overwriting the existing file in wp8

问题描述

我正在制作一个应用程序，我想在其中覆盖我的文件，就像我在文件中写入一个数字并读取但下次我想将新数字添加到现有文件然后读取它

i am making an app in which i want to overwrite my file , like i am writing a number in the file and reading but the next time i want to add the new number to the existing file then read it

为了写入文件，我正在使用代码

for writing into the file i am using the code

private async void cross_Click(object sender, RoutedEventArgs e)
{


    byte[] fileBytes = System.Text.Encoding.UTF8.GetBytes(this.ScoreTB.Text.ToCharArray());

    StorageFolder local = Windows.Storage.ApplicationData.Current.LocalFolder;

    var dataFolder = await local.CreateFolderAsync("MyFolder", CreationCollisionOption.OpenIfExists);

    var file = await dataFolder.CreateFileAsync("MyFile.txt", CreationCollisionOption.ReplaceExisting);

    using (var s = await file.OpenStreamForWriteAsync())
    {
        s.Write(fileBytes, 0, fileBytes.Length);
    }
}

和读取文件

private async void aboutus_Click(object sender, RoutedEventArgs e)
{
    StorageFolder local = Windows.Storage.ApplicationData.Current.LocalFolder;

    if (local != null)
    {
        // Get the DataFolder folder.
        var dataFolder = await local.GetFolderAsync("MyFolder");

        // Get the file.
        var file = await dataFolder.OpenStreamForReadAsync("MyFile.txt");

        // Read the data.
        using (StreamReader streamReader = new StreamReader(file))
        {
            this.Score.Text = streamReader.ReadToEnd();
        }
    }
    else
    {
        MessageBox.Show("No File Created");
    }
}

请帮助我如何在 Windows 手机应用程序开发中覆盖现有文件.

just help me how to overwrite a existing file in windows phone app development.

提前致谢

推荐答案

据我所知，您不需要覆盖，而是需要追加.

As I understand, you don't need an overwrite, but append.

1) 将 ReplaceExisting 改为 OpenIfExists:

  var file = await dataFolder.CreateFileAsync("MyFile.txt", CreationCollisionOption.OpenIfExists );

2) 在写入前寻找流的末尾:

2) seek to the end of the stream before write:

  using (var s = await file.OpenStreamForWriteAsync())
  {
    s.Seek(0, SeekOrigin.End );
    s.Write(fileBytes, 0, fileBytes.Length);
  }

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