WindowsRuntimeStorageExtensions.OpenStreamForWriteAsync 方法

参考

定义

命名空间:: System.IO

程序集:: System.Runtime.WindowsRuntime.dll

重要

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重载

OpenStreamForWriteAsync(IStorageFile)	检索流以写入指定的文件。
OpenStreamForWriteAsync(IStorageFolder, String, CreationCollisionOption)	检索流以在指定的父文件夹中写入文件。

OpenStreamForWriteAsync(IStorageFile)

重要

此 API 不符合 CLS。

检索流以写入指定的文件。

public:
[System::Runtime::CompilerServices::Extension]
 static System::Threading::Tasks::Task<System::IO::Stream ^> ^ OpenStreamForWriteAsync(Windows::Storage::IStorageFile ^ windowsRuntimeFile);

[System.CLSCompliant(false)]
public static System.Threading.Tasks.Task<System.IO.Stream> OpenStreamForWriteAsync (this Windows.Storage.IStorageFile windowsRuntimeFile);

[<System.CLSCompliant(false)>]
static member OpenStreamForWriteAsync : Windows.Storage.IStorageFile -> System.Threading.Tasks.Task<System.IO.Stream>

<Extension()>
Public Function OpenStreamForWriteAsync (windowsRuntimeFile As IStorageFile) As Task(Of Stream)

参数

windowsRuntimeFile: IStorageFile

要写入的 Windows 运行时 IStorageFile 对象。

Task<Stream>

表示异步写入操作的任务。

属性: CLSCompliantAttribute

例外

ArgumentNullException

windowsRuntimeFile 为 null。

IOException

无法以流的形式打开或检索文件。

示例

以下示例演示如何在 Windows 应用商店应用中以打开文件， Stream 并使用类的 StreamReader 实例写入文件。

using System;
using System.IO;
using Windows.Storage;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace ExampleApplication
{
    public sealed partial class BlankPage : Page
    {
        public BlankPage()
        {
            this.InitializeComponent();
        }

        private async void CreateButton_Click(object sender, RoutedEventArgs e)
        {
            StorageFile newFile = await ApplicationData.Current.LocalFolder.CreateFileAsync("testfile3.txt");

            using (StreamWriter writer = new StreamWriter(await newFile.OpenStreamForWriteAsync()))
            {
                await writer.WriteLineAsync("new entry");
                await writer.WriteLineAsync(UserText.Text);
            }
        }

        private async void VerifyButton_Click(object sender, RoutedEventArgs e)
        {
            StorageFile openedFile = await ApplicationData.Current.LocalFolder.GetFileAsync("testfile3.txt");
            using (StreamReader reader = new StreamReader(await openedFile.OpenStreamForReadAsync()))
            {
                Results.Text = await reader.ReadToEndAsync();
            }
        }
    }
}

Imports System.IO
Imports Windows.Storage

NotInheritable Public Class BlankPage
    Inherits Page

    Private Async Sub CreateButton_Click(sender As Object, e As RoutedEventArgs)
        Dim newFile As StorageFile = Await ApplicationData.Current.LocalFolder.CreateFileAsync("testfile4.txt")

        Using writer As StreamWriter = New StreamWriter(Await newFile.OpenStreamForWriteAsync())
            Await writer.WriteLineAsync("new entry")
            Await writer.WriteLineAsync(UserText.Text)
        End Using
    End Sub

    Private Async Sub VerifyButton_Click(sender As Object, e As RoutedEventArgs)
        Dim openedFile As StorageFile = Await ApplicationData.Current.LocalFolder.GetFileAsync("testfile4.txt")
        Using reader As StreamReader = New StreamReader(Await openedFile.OpenStreamForReadAsync())
            Results.Text = Await reader.ReadToEndAsync()
        End Using
    End Sub
End Class

下一个示例演示与上一个示例关联的 XAML 代码。

<Page
    x:Class="ExampleApplication.BlankPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:ExampleApplication"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <StackPanel Background="{StaticResource ApplicationPageBackgroundBrush}" VerticalAlignment="Center" HorizontalAlignment="Center">
        <TextBlock Text="Provide text to write to file:"></TextBlock>
        <TextBox Name="UserText" Width="400"></TextBox>
        <Button Name="CreateButton" Content="Create File" Click="CreateButton_Click"></Button>
        <Button Name="VerifyButton" Content="Verify Contents" Click="VerifyButton_Click"></Button>
        <TextBlock Name="Results"></TextBlock>
    </StackPanel>
</Page>

注解

注意

在 Visual Basic 和 C# 中，可以在类型 IStorageFile为的任何对象上调用此方法作为实例方法。当使用实例方法语法调用此方法时，请省略第一个参数。有关详细信息，请参阅扩展方法 (Visual Basic) 或扩展方法 (C# 编程指南) 。

适用于

OpenStreamForWriteAsync(IStorageFolder, String, CreationCollisionOption)

重要

此 API 不符合 CLS。

检索流以在指定的父文件夹中写入文件。

public:
[System::Runtime::CompilerServices::Extension]
 static System::Threading::Tasks::Task<System::IO::Stream ^> ^ OpenStreamForWriteAsync(Windows::Storage::IStorageFolder ^ rootDirectory, System::String ^ relativePath, Windows::Storage::CreationCollisionOption creationCollisionOption);

[System.CLSCompliant(false)]
public static System.Threading.Tasks.Task<System.IO.Stream> OpenStreamForWriteAsync (this Windows.Storage.IStorageFolder rootDirectory, string relativePath, Windows.Storage.CreationCollisionOption creationCollisionOption);

[<System.CLSCompliant(false)>]
static member OpenStreamForWriteAsync : Windows.Storage.IStorageFolder * string * Windows.Storage.CreationCollisionOption -> System.Threading.Tasks.Task<System.IO.Stream>

<Extension()>
Public Function OpenStreamForWriteAsync (rootDirectory As IStorageFolder, relativePath As String, creationCollisionOption As CreationCollisionOption) As Task(Of Stream)

参数

rootDirectory: IStorageFolder

包含要写入文件的 Windows 运行时 IStorageFile 对象。

relativePath: String

相对于根文件夹，到要写入的文件的路径。

creationCollisionOption: CreationCollisionOption

指定要生成的文件名与现有文件名称相同时要使用的行为的 Windows 运行时 CreationCollisionOption 枚举值。

Task<Stream>

表示异步写入操作的任务。

属性: CLSCompliantAttribute

例外

ArgumentNullException

rootDirectory 或 relativePath 为 null。

ArgumentException

relativePath 为空，或者只包含空白字符。