在任何应用程序中，最重要的是数据之一.如果您是 .net 开发人员，您可能知道隔离存储，并且通过通用Windows平台(UWP)应用程序遵循相同的概念.
这些是您的应用程序可以访问数据的区域.该应用程序包含一些区域，该区域是该特定应用程序专用的，其他区域无法访问，但还有许多其他区域，您可以在其中存储和保存数据.
以下是每个文件夹的简要说明.
| S.No. | Folder&说明 |
|---|---|
| 1 | App package folder 包管理器将所有应用程序的相关文件安装到App包文件夹中，app只能读取该文件夹中的数据. |
| 2 | Local folder 应用程序将本地数据存储到本地文件夹中.它可以存储数据达到存储设备的限制. |
| 3 | Roaming folder 与应用程序相关的设置和属性存储在漫游文件夹中.其他设备也可以访问此文件夹中的数据.每个应用程序的大小限制为100KB. |
| 4 | Temp Folder 临时存储的使用，并且无法保证在您的应用程序再次运行时它仍然可用. |
| 5 | Publisher Share 来自同一发布商的所有应用的共享存储空间.它在app manifest中声明. |
| 6 | Credential Locker 用于密码凭证对象的安全存储. |
| 7 | OneDrive OneDrive是免费在线存储您的Microsoft帐户附带. |
| 8 | Cloud 在云上存储数据. |
| 9 | Known folders 这些文件夹已知的文件夹，例如My图片，视频和音乐. |
| 10 | 可移动存储 USB存储设备或外置硬盘等. |
在Windows 8中，引入了新的API用于文件处理.这些API位于 Windows.Storage 和 Windows.Storage.Streams 命名空间中.您可以使用这些API而不是 System.IO.IsolatedStorage 命名空间.通过使用这些API，可以更轻松地将Windows Phone应用程序移植到Windows应用商店，并且可以轻松地将应用程序升级到Windows的未来版本.
访问本地漫游或临时文件夹，你需要调用这些API :
StorageFolder localFolder = ApplicationData.Current.LocalFolder; StorageFolder roamingFolder = ApplicationData.Current.RoamingFolder; StorageFolder tempFolder = ApplicationData.Current.TemporaryFolder;
要在本地文件夹中创建新文件，请使用以下代码 :
StorageFolder localFolder = ApplicationData.Current.LocalFolder; StorageFile textFile = await localFolder.CreateFileAsync(filename, CreationCollisionOption.ReplaceExisting);
这是打开新创建的文件并在该文件中写入一些内容的代码.
using (IRandomAccessStream textStream = await textFile.OpenAsync(FileAccessMode.ReadWrite)) {
using (DataWriter textWriter = new DataWriter(textStream)){
textWriter.WriteString(contents);
await textWriter.StoreAsync();
}
}您可以从本地文件夹再次打开相同的文件，如给出的代码所示下面.
using (IRandomAccessStream textStream = await textFile.OpenReadAsync()) {
using (DataReader textReader = new DataReader(textStream)){
uint textLength = (uint)textStream.Size;
await textReader.LoadAsync(textLength);
contents = textReader.ReadString(textLength);
}
}要了解数据的读写是如何工作的，让我们一起来看看一个简单的例子.下面给出了添加了不同控件的XAML代码.
<Page
x:Class = "UWPFileHandling.MainPage"
xmlns = "http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x = "http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local = "using:UWPFileHandling"
xmlns:d = "http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc = "http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable = "d">
<Grid Background = "{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Button x:Name = "readFile" Content = "Read Data From File"
HorizontalAlignment = "Left" Margin = "62,518,0,0"
VerticalAlignment = "Top" Height = "37" Width = "174"
Click = "readFile_Click"/>
<TextBox x:FieldModifier = "public" x:Name = "textBox"
HorizontalAlignment = "Left" Margin = "58,145,0,0" TextWrapping = "Wrap"
VerticalAlignment = "Top" Height = "276" Width = "245"/>.
<Button x:Name = "writeFile" Content = "Write Data to File"
HorizontalAlignment = "Left" Margin = "64,459,0,0"
VerticalAlignment = "Top" Click = "writeFile_Click"/>
<TextBlock x:Name = "textBlock" HorizontalAlignment = "Left"
Margin = "386,149,0,0" TextWrapping = "Wrap"
VerticalAlignment = "Top" Height = "266" Width = "250"
Foreground = "#FF6231CD"/>
</Grid>
</Page>下面给出了不同事件的C＃实现，以及用于读取和写入文本数据的 FileHelper 类的实现file.
using System;
using System.IO;
using System.Threading.Tasks;
using Windows.Storage;
using Windows.Storage.Streams;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
// The Blank Page item template is documented at
http://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409
namespace UWPFileHandling {
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public partial class MainPage : Page {
const string TEXT_FILE_NAME = "SampleTextFile.txt";
public MainPage(){
this.InitializeComponent();
}
private async void readFile_Click(object sender, RoutedEventArgs e) {
string str = await FileHelper.ReadTextFile(TEXT_FILE_NAME);
textBlock.Text = str;
}
private async void writeFile_Click(object sender, RoutedEventArgs e) {
string textFilePath = await FileHelper.WriteTextFile(TEXT_FILE_NAME, textBox.Text);
}
}
public static class FileHelper {
// Write a text file to the app's local folder.
public static async Task<string>
WriteTextFile(string filename, string contents) {
StorageFolder localFolder = ApplicationData.Current.LocalFolder;
StorageFile textFile = await localFolder.CreateFileAsync(filename,
CreationCollisionOption.ReplaceExisting);
using (IRandomAccessStream textStream = await
textFile.OpenAsync(FileAccessMode.ReadWrite)){
using (DataWriter textWriter = new DataWriter(textStream)){
textWriter.WriteString(contents);
await textWriter.StoreAsync();
}
}
return textFile.Path;
}
// Read the contents of a text file from the app's local folder.
public static async Task<string> ReadTextFile(string filename) {
string contents;
StorageFolder localFolder = ApplicationData.Current.LocalFolder;
StorageFile textFile = await localFolder.GetFileAsync(filename);
using (IRandomAccessStream textStream = await textFile.OpenReadAsync()){
using (DataReader textReader = new DataReader(textStream)){
uint textLength = (uint)textStream.Size;
await textReader.LoadAsync(textLength);
contents = textReader.ReadString(textLength);
}
}
return contents;
}
}
}编译并执行上述代码时，您将看到以下窗口.
现在，你在文本框中写了一些东西然后点击"将数据写入文件"按钮.程序会将数据写入本地文件夹中的文本文件中.如果单击"从文件读取数据"按钮，程序将从同一文本文件中读取数据，该文件位于本地文件夹中，并将显示在文本块中.
