附加到文本文件（不覆蓋！）

Question

另一個Universal Platform App問我，還在學習！

快速問題 - 我需要使用哪種方法將數據寫入文本文件，以便將字符串附加（而不是覆蓋）到文本文件中？ 目前我正在使用一個使用流的異步void，但它覆蓋了我的文件。 以下是創建和寫入文本文件的不同方法： https ： //msdn.microsoft.com/en-us/library/windows/apps/mt185401.aspx

現在這是我的代碼。 是否需要修改以將數據附加到文本文件而不是覆蓋它，或者我是否需要使用其他方法之一來附加數據？

//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.

如果它有任何區別，我的閱讀代碼：

//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;
            }
        }

謝謝。

Answer 1

我沒有在我面前的平台我現在可以測試，但是這應該可以獲得現有文件的長度並將編寫器放在最后（新文件應該返回0）：

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

Answer 2

除了獲取流之外，您還可以使用FileIO類。 例如方法AppendTextAsync ：

await FileIO.AppendTextAsync(ticketsFile, "Submitted: " + submitDate + "\n" + "Problem: " + problem + "\n" + "Room: " + location + "\n" + "Description: " + descriptionText.Text + "\n" + "Priority: " + priority + "\n");