WindowsRuntimeStreamExtensions.AsStreamForWrite Méthode

public:
[System::Runtime::CompilerServices::Extension]
 static System::IO::Stream ^ AsStreamForWrite(Windows::Storage::Streams::IOutputStream ^ windowsRuntimeStream);

[System.CLSCompliant(false)]
public static System.IO.Stream AsStreamForWrite(this Windows.Storage.Streams.IOutputStream windowsRuntimeStream);

[<System.CLSCompliant(false)>]
static member AsStreamForWrite : Windows.Storage.Streams.IOutputStream -> System.IO.Stream

<Extension()>
Public Function AsStreamForWrite (windowsRuntimeStream As IOutputStream) As Stream

Paramètres

Retours

Flux converti.

Attributs

CLSCompliantAttribute

Exceptions

Exemples

L’exemple suivant montre comment utiliser les méthodes AsStreamForWrite et AsStreamForRead pour convertir un flux managé vers et à partir d’un flux dans le Windows Runtime.

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("testfile.txt");
            var streamNewFile = await newFile.OpenAsync(FileAccessMode.ReadWrite);

            using (var outputNewFile = streamNewFile.GetOutputStreamAt(0))
            {
                using (StreamWriter writer = new StreamWriter(outputNewFile.AsStreamForWrite()))
                {
                    await writer.WriteLineAsync("content for new file");
                    await writer.WriteLineAsync(UserText.Text);
                }
            }
        }

        private async void VerifyButton_Click(object sender, RoutedEventArgs e)
        {
            StorageFile openedFile = await ApplicationData.Current.LocalFolder.GetFileAsync("testfile.txt");
            var streamOpenedFile = await openedFile.OpenAsync(FileAccessMode.Read);

            using (var inputOpenedFile = streamOpenedFile.GetInputStreamAt(0))
            {
                using (StreamReader reader = new StreamReader(inputOpenedFile.AsStreamForRead()))
                {
                    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("testfile.txt")
        Dim streamNewFile = Await newFile.OpenAsync(FileAccessMode.ReadWrite)

        Using outputNewFile = streamNewFile.GetOutputStreamAt(0)
            Using writer As StreamWriter = New StreamWriter(outputNewFile.AsStreamForWrite())
                Await writer.WriteLineAsync("content for new file")
                Await writer.WriteLineAsync(UserText.Text)
            End Using
        End Using
    End Sub

    Private Async Sub VerifyButton_Click(sender As Object, e As RoutedEventArgs)
        Dim openedFile As StorageFile = Await ApplicationData.Current.LocalFolder.GetFileAsync("testfile.txt")
        Dim streamOpenedFile = Await openedFile.OpenAsync(FileAccessMode.Read)

        Using inputOpenedFile = streamOpenedFile.GetInputStreamAt(0)

            Using reader As StreamReader = New StreamReader(inputOpenedFile.AsStreamForRead())
                Results.Text = Await reader.ReadToEndAsync()
            End Using
        End Using
    End Sub
End Class

Voici le code XAML associé à l’exemple précédent.

<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>

Remarques

Une taille de mémoire tampon par défaut de 16 384 octets est utilisée lors de la conversion du flux. Pour spécifier une taille de mémoire tampon différente, utilisez la AsStreamForWrite(IOutputStream, Int32) surcharge.

public:
[System::Runtime::CompilerServices::Extension]
 static System::IO::Stream ^ AsStreamForWrite(Windows::Storage::Streams::IOutputStream ^ windowsRuntimeStream, int bufferSize);

[System.CLSCompliant(false)]
public static System.IO.Stream AsStreamForWrite(this Windows.Storage.Streams.IOutputStream windowsRuntimeStream, int bufferSize);

[<System.CLSCompliant(false)>]
static member AsStreamForWrite : Windows.Storage.Streams.IOutputStream * int -> System.IO.Stream

<Extension()>
Public Function AsStreamForWrite (windowsRuntimeStream As IOutputStream, bufferSize As Integer) As Stream

Paramètres

Retours

Flux converti.

Attributs

CLSCompliantAttribute

Exceptions

Remarques

Vous utilisez cette méthode pour spécifier une taille de mémoire tampon lors de la conversion du flux. Pour utiliser la taille de mémoire tampon par défaut de 16 384 octets, utilisez la AsStreamForWrite(IOutputStream) surcharge.

Dans la plupart des cas, la mise en mémoire tampon améliore les performances des opérations de flux. Vous pouvez désactiver la mise en mémoire tampon en définissant bufferSize sur zéro, mais vous devez le faire uniquement lorsque vous êtes sûr que la désactivation de la mise en mémoire tampon est appropriée pour votre situation.