Marshal 类
定义
重要
一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。 对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。
提供了一个方法集合，这些方法用于分配非托管内存、复制非托管内存块、将托管类型转换为非托管类型，此外还提供了在与非托管代码交互时使用的其他杂项方法。
public ref class Marshal abstract sealedpublic ref class Marshal sealedpublic static class Marshalpublic sealed class Marshaltype Marshal = classPublic Class MarshalPublic NotInheritable Class Marshal- 继承
-
Marshal
示例
以下示例演示如何使用 由 Marshal 类定义的各种方法。
using namespace System;
using namespace System::Runtime::InteropServices;
public value struct Point
{
public:
property int X;
property int Y;
};
extern bool CloseHandle(IntPtr h);
int main()
{
// Demonstrate the use of public static fields of the Marshal
// class.
Console::WriteLine(
"SystemDefaultCharSize={0},SystemMaxDBCSCharSize={1}",
Marshal::SystemDefaultCharSize,
Marshal::SystemMaxDBCSCharSize);
// Demonstrate the use of the SizeOf method of the Marshal
// class.
Console::WriteLine("Number of bytes needed by a Point object: {0}",
Marshal::SizeOf(Point::typeid));
Point point;
Console::WriteLine("Number of bytes needed by a Point object: {0}",
Marshal::SizeOf(point));
// Demonstrate how to call GlobalAlloc and
// GlobalFree using the Marshal class.
IntPtr hglobal = Marshal::AllocHGlobal(100);
Marshal::FreeHGlobal(hglobal);
// Demonstrate how to use the Marshal class to get the Win32
// error code when a Win32 method fails.
bool isCloseHandleSuccess = CloseHandle(IntPtr(-1));
if (!isCloseHandleSuccess)
{
Console::WriteLine(
"CloseHandle call failed with an error code of: {0}",
Marshal::GetLastWin32Error());
}
};
// This is a platform invoke prototype. SetLastError is true,
// which allows the GetLastWin32Error method of the Marshal class
// to work correctly.
[DllImport("Kernel32", ExactSpelling = true, SetLastError = true)]
extern bool CloseHandle(IntPtr h);
// This code produces the following output.
//
// SystemDefaultCharSize=2, SystemMaxDBCSCharSize=1
// Number of bytes needed by a Point object: 8
// Number of bytes needed by a Point object: 8
// CloseHandle call failed with an error code of: 6
using System;
using System.Text;
using System.Runtime.InteropServices;
public struct Point
{
public Int32 x, y;
}
public sealed class App
{
static void Main()
{
// Demonstrate the use of public static fields of the Marshal class.
Console.WriteLine("SystemDefaultCharSize={0}, SystemMaxDBCSCharSize={1}",
Marshal.SystemDefaultCharSize, Marshal.SystemMaxDBCSCharSize);
// Demonstrate the use of the SizeOf method of the Marshal class.
Console.WriteLine("Number of bytes needed by a Point object: {0}",
Marshal.SizeOf(typeof(Point)));
Point p = new Point();
Console.WriteLine("Number of bytes needed by a Point object: {0}",
Marshal.SizeOf(p));
// Demonstrate how to call GlobalAlloc and
// GlobalFree using the Marshal class.
IntPtr hglobal = Marshal.AllocHGlobal(100);
Marshal.FreeHGlobal(hglobal);
// Demonstrate how to use the Marshal class to get the Win32 error
// code when a Win32 method fails.
Boolean f = CloseHandle(new IntPtr(-1));
if (!f)
{
Console.WriteLine("CloseHandle call failed with an error code of: {0}",
Marshal.GetLastWin32Error());
}
}
// This is a platform invoke prototype. SetLastError is true, which allows
// the GetLastWin32Error method of the Marshal class to work correctly.
[DllImport("Kernel32", ExactSpelling = true, SetLastError = true)]
static extern Boolean CloseHandle(IntPtr h);
}
// This code produces the following output.
//
// SystemDefaultCharSize=2, SystemMaxDBCSCharSize=1
// Number of bytes needed by a Point object: 8
// Number of bytes needed by a Point object: 8
// CloseHandle call failed with an error code of: 6
Imports System.Text
Imports System.Runtime.InteropServices
Imports System.Security.Permissions
Public Structure Point
Public x, y As Int32
End Structure
Public NotInheritable Class App
<SecurityPermission(SecurityAction.LinkDemand, Unrestricted:=True)> _
Shared Sub Main()
' Demonstrate the use of public static fields of the Marshal class.
Console.WriteLine("SystemDefaultCharSize={0}, SystemMaxDBCSCharSize={1}", Marshal.SystemDefaultCharSize, Marshal.SystemMaxDBCSCharSize)
' Demonstrate the use of the SizeOf method of the Marshal class.
Console.WriteLine("Number of bytes needed by a Point object: {0}", Marshal.SizeOf(GetType(Point)))
Dim p As New Point()
Console.WriteLine("Number of bytes needed by a Point object: {0}", Marshal.SizeOf(p))
' Demonstrate how to call GlobalAlloc and
' GlobalFree using the Marshal class.
Dim hglobal As IntPtr = Marshal.AllocHGlobal(100)
Marshal.FreeHGlobal(hglobal)
' Demonstrate how to use the Marshal class to get the Win32 error
' code when a Win32 method fails.
Dim f As [Boolean] = CloseHandle(New IntPtr(-1))
If Not f Then
Console.WriteLine("CloseHandle call failed with an error code of: {0}", Marshal.GetLastWin32Error())
End If
End Sub
' This is a platform invoke prototype. SetLastError is true, which allows
' the GetLastWin32Error method of the Marshal class to work correctly.
<DllImport("Kernel32", ExactSpelling:=True, SetLastError:=True)> _
Shared Function CloseHandle(ByVal h As IntPtr) As [Boolean]
End Function
End Class
' This code produces the following output.
'
' SystemDefaultCharSize=2, SystemMaxDBCSCharSize=1
' Number of bytes needed by a Point object: 8
' Number of bytes needed by a Point object: 8
' CloseHandle call failed with an error code of: 6
注解
类 static 上 Marshal 定义的方法对于使用非托管代码至关重要。 此类中定义的大多数方法通常由想要在托管和非托管编程模型之间提供桥梁的开发人员使用。 例如， StringToHGlobalAnsi 方法将托管堆) 的指定字符串 (的 ANSI 字符复制到非托管堆中的缓冲区。 它还分配大小正确的目标堆。
公共语言运行时提供特定的封送处理功能。 有关封送处理行为的详细信息，请参阅 互操作封送处理。
Read类中的 Marshal 和 Write 方法支持对齐和未对齐的访问。
字段
| SystemDefaultCharSize |
表示系统上的默认字符大小；Unicode 系统上默认值为 2，ANSI 系统上默认值为 1。 此字段为只读。 |
| SystemMaxDBCSCharSize |
表示用于当前操作系统的双字节字符集 (DBCS) 的最大大小（以字节为单位）。 此字段为只读。 |
