WindowsRuntimeStreamExtensions.AsStreamForWrite 方法

定义

重载

AsStreamForWrite(IOutputStream)

将 Windows 运行时中的输出流转换为适用于 Windows 8.x 应用商店应用的 .NET 中的托管流。Converts an output stream in the Windows Runtime to a managed stream in the .NET for Windows 8.x Store apps.

AsStreamForWrite(IOutputStream, Int32)

将 Windows 运行时中的输出流转换为适用于 Windows 应用商店应用的 .NET 中使用指定缓冲区大小的托管流。Converts an output stream in the Windows Runtime to a managed stream in the .NET for Windows Store apps using the specified buffer size.

AsStreamForWrite(IOutputStream)

重要

此 API 不符合 CLS。

将 Windows 运行时中的输出流转换为适用于 Windows 8.x 应用商店应用的 .NET 中的托管流。Converts an output stream in the Windows Runtime to a managed stream in the .NET for Windows 8.x Store apps.

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);
static member AsStreamForWrite : Windows.Storage.Streams.IOutputStream -> System.IO.Stream
<Extension()>
Public Function AsStreamForWrite (windowsRuntimeStream As IOutputStream) As Stream

参数

windowsRuntimeStream
IOutputStream

要转换的 Windows 运行时 对象。The Windows Runtime object to convert.

返回

已转换的流。The converted stream.

属性

异常

windowsRuntimeStreamnullwindowsRuntimeStream is null.

示例

下面的示例演示如何使用AsStreamForWriteAsStreamForRead方法将托管流与 Windows 运行时中的流相互转换。The following example shows how to use the AsStreamForWrite and AsStreamForRead methods to convert a managed stream to and from a stream in the 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

下面是与上一个示例关联的 XAML 代码。Here's the XAML code that is associated with the previous example.

<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

备注

在 Visual Basic 和C#中, 你可以在类型Stream为的任何对象上将此方法作为实例方法来调用。In Visual Basic and C#, you can call this method as an instance method on any object of type Stream. 当使用实例方法语法调用此方法时,请省略第一个参数。When you use instance method syntax to call this method, omit the first parameter. 有关详细信息, 请参阅扩展方法 (Visual Basic)扩展方法C# (编程指南)For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

转换流时, 将使用默认缓冲区大小16384字节。A default buffer size of 16,384 bytes is used when converting the stream. 若要指定不同的缓冲区大小, 请AsStreamForWrite(IOutputStream, Int32)使用重载。To specify a different buffer size, use the AsStreamForWrite(IOutputStream, Int32) overload.

AsStreamForWrite(IOutputStream, Int32)

重要

此 API 不符合 CLS。

将 Windows 运行时中的输出流转换为适用于 Windows 应用商店应用的 .NET 中使用指定缓冲区大小的托管流。Converts an output stream in the Windows Runtime to a managed stream in the .NET for Windows Store apps using the specified buffer size.

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);
static member AsStreamForWrite : Windows.Storage.Streams.IOutputStream * int -> System.IO.Stream
<Extension()>
Public Function AsStreamForWrite (windowsRuntimeStream As IOutputStream, bufferSize As Integer) As Stream

参数

windowsRuntimeStream
IOutputStream

要转换的 Windows 运行时 IOutputStream 对象。The Windows Runtime IOutputStream object to convert.

bufferSize
Int32

缓冲区的大小(以字节为单位)。The size, in bytes, of the buffer. 此值不能为负,但是,它可以是(0)禁用缓冲的 0。This value cannot be negative, but it can be 0 (zero) to disable buffering.

返回

已转换的流。The converted stream.

属性

异常

windowsRuntimeStreamnullwindowsRuntimeStream is null.

bufferSize 为负数。bufferSize is negative.

注解

备注

在 Visual Basic 和C#中, 你可以在类型Stream为的任何对象上将此方法作为实例方法来调用。In Visual Basic and C#, you can call this method as an instance method on any object of type Stream. 当使用实例方法语法调用此方法时,请省略第一个参数。When you use instance method syntax to call this method, omit the first parameter. 有关详细信息, 请参阅扩展方法 (Visual Basic)扩展方法C# (编程指南)For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

在转换流时, 可以使用此方法指定缓冲区大小。You use this method to specify a buffer size when converting the stream. 若要使用默认缓冲区大小16384字节, 请使用AsStreamForWrite(IOutputStream)重载。To use the default buffer size of 16,384 bytes, use the AsStreamForWrite(IOutputStream) overload.

在大多数情况下, 缓冲会提高流操作的性能。In most situations, buffering improves the performance of stream operations. 你可以通过将设置bufferSize为零来禁用缓冲, 但只有在确定禁用缓冲适用于你的情况下, 才应执行此操作。You can disable buffering by setting bufferSize to zero, but you should do this only when you are sure that disabling buffering is appropriate for your situation.

适用于