MemoryMappedFile.OpenExisting 方法

参考

定义

命名空间:: System.IO.MemoryMappedFiles

程序集:: System.IO.MemoryMappedFiles.dll

程序集:: System.Core.dll

程序集:: netstandard.dll

重要

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在系统内存中打开现有的已命名内存映射文件。

重载

OpenExisting(String)	在系统内存中打开一个具有指定名称的现有内存映射文件。
OpenExisting(String, MemoryMappedFileRights)	在系统内存中打开一个具有指定名称和访问权限的现有内存映射文件。
OpenExisting(String, MemoryMappedFileRights, HandleInheritability)	在系统内存中打开一个具有指定名称、访问权限和继承性的现有内存映射文件。

OpenExisting(String)

Source:: MemoryMappedFile.cs

Source:: MemoryMappedFile.cs

Source:: MemoryMappedFile.cs

在系统内存中打开一个具有指定名称的现有内存映射文件。

public:
 static System::IO::MemoryMappedFiles::MemoryMappedFile ^ OpenExisting(System::String ^ mapName);

[System.Runtime.Versioning.SupportedOSPlatform("windows")]
public static System.IO.MemoryMappedFiles.MemoryMappedFile OpenExisting (string mapName);

public static System.IO.MemoryMappedFiles.MemoryMappedFile OpenExisting (string mapName);

[<System.Runtime.Versioning.SupportedOSPlatform("windows")>]
static member OpenExisting : string -> System.IO.MemoryMappedFiles.MemoryMappedFile

static member OpenExisting : string -> System.IO.MemoryMappedFiles.MemoryMappedFile

Public Shared Function OpenExisting (mapName As String) As MemoryMappedFile

参数

mapName: String

内存映射文件的名称。

MemoryMappedFile

具有指定名称的内存映射文件。

属性: SupportedOSPlatformAttribute

例外

ArgumentNullException

mapName 为 null。

ArgumentException

mapName 是一个空字符串。

FileNotFoundException

为 mapName 指定的文件不存在。

示例

打开持久化 Memory-Mapped 文件

以下示例打开一个名为的 ImgA 内存映射文件，该文件已从磁盘上的文件 (创建，如方法) 的示例 CreateFromFile(String) 所示。

using System;
using System.IO.MemoryMappedFiles;
using System.Runtime.InteropServices;

class Program
{
    static void Main(string[] args)
    {
        // Assumes another process has created the memory-mapped file.
        using (var mmf = MemoryMappedFile.OpenExisting("ImgA"))
        {
            using (var accessor = mmf.CreateViewAccessor(4000000, 2000000))
            {
                int colorSize = Marshal.SizeOf(typeof(MyColor));
                MyColor color;

                // Make changes to the view.
                for (long i = 0; i < 1500000; i += colorSize)
                {
                    accessor.Read(i, out color);
                    color.Brighten(20);
                    accessor.Write(i, ref color);
                }
            }
        }
    }
}

public struct MyColor
{
    public short Red;
    public short Green;
    public short Blue;
    public short Alpha;

    // Make the view brigher.
    public void Brighten(short value)
    {
        Red = (short)Math.Min(short.MaxValue, (int)Red + value);
        Green = (short)Math.Min(short.MaxValue, (int)Green + value);
        Blue = (short)Math.Min(short.MaxValue, (int)Blue + value);
        Alpha = (short)Math.Min(short.MaxValue, (int)Alpha + value);
    }
}

Imports System.IO.MemoryMappedFiles
Imports System.Runtime.InteropServices

Class Program
    Public Shared Sub Main(ByVal args As String())
        ' Assumes another process has created the memory-mapped file.
        Using mmf = MemoryMappedFile.OpenExisting("ImgA")
            Using accessor = mmf.CreateViewAccessor(4000000, 2000000)
                Dim colorSize As Integer = Marshal.SizeOf(GetType(MyColor))
                Dim color As MyColor

                ' Make changes to the view.
                Dim i As Long = 0
                While i < 1500000
                    accessor.Read(i, color)
                    color.Brighten(30)
                    accessor.Write(i, color)
                    i += colorSize
                End While
            End Using
        End Using
    End Sub
End Class

Public Structure MyColor
    Public Red As Short
    Public Green As Short
    Public Blue As Short
    Public Alpha As Short

    ' Make the view brigher.
    Public Sub Brighten(ByVal value As Short)
        Red = CShort(Math.Min(Short.MaxValue, CInt(Red) + value))
        Green = CShort(Math.Min(Short.MaxValue, CInt(Green) + value))
        Blue = CShort(Math.Min(Short.MaxValue, CInt(Blue) + value))
        Alpha = CShort(Math.Min(Short.MaxValue, CInt(Alpha) + value))
    End Sub
End Structure

打开非持久化 Memory-Mapped 文件

以下示例打开用于进程间通信的内存映射文件。此代码示例是为方法提供的更大示例的 CreateNew(String, Int64) 一部分。

注解

内存映射文件可以是与磁盘上的文件关联的持久内存映射文件 () ，也可以是非持久化文件。

另请参阅

内存映射文件

适用于

OpenExisting(String, MemoryMappedFileRights)

Source:: MemoryMappedFile.cs

Source:: MemoryMappedFile.cs

Source:: MemoryMappedFile.cs

在系统内存中打开一个具有指定名称和访问权限的现有内存映射文件。

public:
 static System::IO::MemoryMappedFiles::MemoryMappedFile ^ OpenExisting(System::String ^ mapName, System::IO::MemoryMappedFiles::MemoryMappedFileRights desiredAccessRights);

[System.Runtime.Versioning.SupportedOSPlatform("windows")]
public static System.IO.MemoryMappedFiles.MemoryMappedFile OpenExisting (string mapName, System.IO.MemoryMappedFiles.MemoryMappedFileRights desiredAccessRights);

public static System.IO.MemoryMappedFiles.MemoryMappedFile OpenExisting (string mapName, System.IO.MemoryMappedFiles.MemoryMappedFileRights desiredAccessRights);

[<System.Runtime.Versioning.SupportedOSPlatform("windows")>]
static member OpenExisting : string * System.IO.MemoryMappedFiles.MemoryMappedFileRights -> System.IO.MemoryMappedFiles.MemoryMappedFile

static member OpenExisting : string * System.IO.MemoryMappedFiles.MemoryMappedFileRights -> System.IO.MemoryMappedFiles.MemoryMappedFile

Public Shared Function OpenExisting (mapName As String, desiredAccessRights As MemoryMappedFileRights) As MemoryMappedFile

参数

mapName: String

要打开的内存映射文件的名称。

desiredAccessRights: MemoryMappedFileRights

指定要应用于内存映射文件的访问权限的枚举值之一。

MemoryMappedFile

具有指定特征的内存映射文件。

属性: SupportedOSPlatformAttribute

例外

ArgumentNullException

mapName 为 null。

ArgumentException

mapName 是一个空字符串。

ArgumentOutOfRangeException

desiredAccessRights 不是有效的 MemoryMappedFileRights 枚举值。

FileNotFoundException

为 mapName 指定的文件不存在。

另请参阅

内存映射文件

适用于

OpenExisting(String, MemoryMappedFileRights, HandleInheritability)

Source:: MemoryMappedFile.cs

Source:: MemoryMappedFile.cs

Source:: MemoryMappedFile.cs

在系统内存中打开一个具有指定名称、访问权限和继承性的现有内存映射文件。

public:
 static System::IO::MemoryMappedFiles::MemoryMappedFile ^ OpenExisting(System::String ^ mapName, System::IO::MemoryMappedFiles::MemoryMappedFileRights desiredAccessRights, System::IO::HandleInheritability inheritability);

[System.Runtime.Versioning.SupportedOSPlatform("windows")]
public static System.IO.MemoryMappedFiles.MemoryMappedFile OpenExisting (string mapName, System.IO.MemoryMappedFiles.MemoryMappedFileRights desiredAccessRights, System.IO.HandleInheritability inheritability);

public static System.IO.MemoryMappedFiles.MemoryMappedFile OpenExisting (string mapName, System.IO.MemoryMappedFiles.MemoryMappedFileRights desiredAccessRights, System.IO.HandleInheritability inheritability);

[System.Security.SecurityCritical]
public static System.IO.MemoryMappedFiles.MemoryMappedFile OpenExisting (string mapName, System.IO.MemoryMappedFiles.MemoryMappedFileRights desiredAccessRights, System.IO.HandleInheritability inheritability);

[<System.Runtime.Versioning.SupportedOSPlatform("windows")>]
static member OpenExisting : string * System.IO.MemoryMappedFiles.MemoryMappedFileRights * System.IO.HandleInheritability -> System.IO.MemoryMappedFiles.MemoryMappedFile

static member OpenExisting : string * System.IO.MemoryMappedFiles.MemoryMappedFileRights * System.IO.HandleInheritability -> System.IO.MemoryMappedFiles.MemoryMappedFile

[<System.Security.SecurityCritical>]
static member OpenExisting : string * System.IO.MemoryMappedFiles.MemoryMappedFileRights * System.IO.HandleInheritability -> System.IO.MemoryMappedFiles.MemoryMappedFile

Public Shared Function OpenExisting (mapName As String, desiredAccessRights As MemoryMappedFileRights, inheritability As HandleInheritability) As MemoryMappedFile