c# - append 到文本文件(不覆盖!)

Question

我提出的另一个 Universal Platform App 问题，仍在学习中!

快速提问 - 我需要使用哪种方法将数据写入文本文件以将字符串追加(而不是覆盖)到文本文件？目前我正在使用 async void using streams 但它正在覆盖我的文件。以下是创建和写入文本文件的不同方式:https://msdn.microsoft.com/en-us/library/windows/apps/mt185401.aspx

目前这是我的代码。是否需要修改以将数据 append 到文本文件而不是覆盖它，或者我是否需要使用其他方法之一来 append 数据？

//WRITE
        //Create the text file to hold the data
        Windows.Storage.StorageFolder storageFolder = Windows.Storage.ApplicationData.Current.LocalFolder;
        Windows.Storage.StorageFile ticketsFile = await storageFolder.CreateFileAsync("tickets.txt", Windows.Storage.CreationCollisionOption.OpenIfExists);

        //Use stream to write to the file
        var stream = await ticketsFile.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);

        using (var outputStream = stream.GetOutputStreamAt(0))
        {
            using (var dataWriter = new Windows.Storage.Streams.DataWriter(outputStream))
            {
                dataWriter.WriteString("Submitted: " + submitDate + "\n" + "Problem: " + problem + "\n" + "Room: " + location + "\n" + "Description: " + descriptionText.Text + "\n" + "Priority: " + priority + "\n");
                await dataWriter.StoreAsync();
                await outputStream.FlushAsync();
            }
        }
        stream.Dispose(); // Or use the stream variable (see previous code snippet) with a using statement as well.

如果有任何不同，我阅读的代码:

//READ
        //Open the text file
        stream = await ticketsFile.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);
        ulong size = stream.Size;

        using (var inputStream = stream.GetInputStreamAt(0))
        {
            using (var dataReader = new Windows.Storage.Streams.DataReader(inputStream))
            {
                uint numBytesLoaded = await dataReader.LoadAsync((uint)size);
                string savedTickets = dataReader.ReadString(numBytesLoaded);

                textBox.Text = savedTickets;
            }
        }

谢谢。

Answer 1

我面前没有我现在可以测试的平台，但这应该可以获取现有文件的长度并将编写器放在最后(新文件应返回 0):

使用(var outputStream = stream.GetOutputStreamAt(stream.Size))