Marshal 类

.NET Framework 类库 

  Marshal 类

提供了一个方法集，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。

命名空间:System.Runtime.InteropServices
程序集:mscorlib（在 mscorlib.dll 中）

Visual Basic（声明）

Class Marshal

Visual Basic（用法）

可对静态类的成员直接进行访问，无需类的实例。

C#

class Marshal

C++

class Marshal abstract sealed

J#

class Marshal

JScript

class Marshal

Marshal 类中定义的 static 方法对于处理非托管代码至关重要。此类中定义的大多数方法通常由需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 ANSI 字符从指定的字符串（在托管堆中）复制到非托管堆中的缓冲区。该方法还分配大小正确的目标堆。

公共语言运行库提供了特定的封送处理功能。有关封送处理行为的详细信息，请参见 互操作封送处理。

下面的代码示例演示如何使用 Marshal 类所定义的各个方法。

C#

复制代码

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

C++

复制代码

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