如何正确地使用Windows读写文件.Windows Phone 8的存储空间

本文关键字：Windows Phone 存储空间 文件 读写 正确地 | 更新日期: 2023-09-27 18:05:40

我需要的只是简单地写入文件，并从Windows Phone 8中使用Windows读取文件。存储api。使用旧的IsolatedStorage方法这相对容易，但使用新的WinRT API则要困难得多。

我一直在试着写它，但似乎有所有这些奇怪的东西，如IBuffer。等。使用完整版的WinRT，使用Windows.Storage.FileIO非常容易，它的存在似乎是为了防止像我这样的开发人员发疯。然而，它没有在Phone版本中实现。另外，我观看了Channel9的一个视频，其中展示了一些代码示例，但是他们有一个错误，他们使用标记为Security Critical的方法来获取常规流。显然，获得常规流是不允许的。

所以，有人能给我提供一个简洁而正确的片段，关于如何将文件读取为字符串，以及如何将字符串写入文件，并完成正确的使用和处理技术?

如何正确地使用Windows读写文件.Windows Phone 8的存储空间

下面是一个简单的例子:

public async Task WriteDataToFileAsync(string fileName, string content)
{
    byte[] data = Encoding.Unicode.GetBytes(content);
    var folder = ApplicationData.Current.LocalFolder;
    var file = await folder.CreateFileAsync(fileName, CreationCollisionOption.ReplaceExisting);
    using (var s = await file.OpenStreamForWriteAsync())
    {
        await s.WriteAsync(data, 0, data.Length);
    }
}
public async Task<string> ReadFileContentsAsync(string fileName)
{
    var folder = ApplicationData.Current.LocalFolder;
    try
    {
        var file = await folder.OpenStreamForReadAsync(fileName);
        using (var streamReader = new StreamReader(file))
        {
            return streamReader.ReadToEnd();
        }
    }
    catch (Exception)
    {
        return string.Empty;
    }
}

像这样使用它们:

await this.WriteDataToFileAsync("afile.txt", "some text to save in a file");
var contents = await this.ReadFileContentsAsync("afile.txt");

我还没有在Windows Phone 8上尝试过，但这里是WinRT XAML工具包在Windows 8上可以工作的。



using System;
using System.Threading.Tasks;
using Windows.Storage;
using Windows.Storage.Streams;
namespace WinRTXamlToolkit.IO.Extensions
{
    /// <summary>
    /// Extensions for simple writing and reading of strings to/from files.
    /// </summary>
    /// <remarks>
    /// Note that these were created before FileIO class existed in WinRT, but they still serve a purpose.
    /// </remarks>
    public static class StringIOExtensions
    {
        /// <summary>
        /// Reads a string from a text file.
        /// </summary>
        /// <param name="fileName">Name of the file.</param>
        /// <param name="folder">The folder.</param>
        /// <returns></returns>
        public static async Task<string> ReadFromFile(
            string fileName,
            StorageFolder folder = null)
        {
            folder = folder ?? ApplicationData.Current.LocalFolder;
            var file = await folder.GetFileAsync(fileName);
            using (var fs = await file.OpenAsync(FileAccessMode.Read))
            {
                using (var inStream = fs.GetInputStreamAt(0))
                {
                    using (var reader = new DataReader(inStream))
                    {
                        await reader.LoadAsync((uint)fs.Size);
                        string data = reader.ReadString((uint)fs.Size);
                        reader.DetachStream();
                        return data;
                    }
                }
            }
        }
        /// <summary>
        /// Writes a string to a text file.
        /// </summary>
        /// <param name="text">The text to write.</param>
        /// <param name="fileName">Name of the file.</param>
        /// <param name="folder">The folder.</param>
        /// <param name="options">
        /// The enum value that determines how responds if the fileName is the same
        /// as the name of an existing file in the current folder. Defaults to ReplaceExisting.
        /// </param>
        /// <returns></returns>
        public static async Task WriteToFile(
            this string text,
            string fileName,
            StorageFolder folder = null,
            CreationCollisionOption options = CreationCollisionOption.ReplaceExisting)
        {
            folder = folder ?? ApplicationData.Current.LocalFolder;
            var file = await folder.CreateFileAsync(
                fileName,
                options);
            using (var fs = await file.OpenAsync(FileAccessMode.ReadWrite))
            {
                using (var outStream = fs.GetOutputStreamAt(0))
                {
                    using (var dataWriter = new DataWriter(outStream))
                    {
                        if (text != null)
                            dataWriter.WriteString(text);
                        await dataWriter.StoreAsync();
                        dataWriter.DetachStream();
                    }
                    await outStream.FlushAsync();
                }
            }
        }
    }
}

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