UnmanagedMarshal 类

注意：此类现在已过时。

表示说明如何将字段从托管代码封送为非托管代码的类。无法继承此类。

**命名空间:**System.Reflection.Emit
**程序集:**mscorlib（在 mscorlib.dll 中）

语法

声明
<SerializableAttribute> _
<ObsoleteAttribute("An alternate API is available: Emit the MarshalAs custom attribute instead. https://go.microsoft.com/fwlink/?linkid=14202")> _
<ComVisibleAttribute(True)> _
Public NotInheritable Class UnmanagedMarshal
用法
Dim instance As UnmanagedMarshal

[SerializableAttribute] 
[ObsoleteAttribute("An alternate API is available: Emit the MarshalAs custom attribute instead. https://go.microsoft.com/fwlink/?linkid=14202")] 
[ComVisibleAttribute(true)] 
public sealed class UnmanagedMarshal

[SerializableAttribute] 
[ObsoleteAttribute(L"An alternate API is available: Emit the MarshalAs custom attribute instead. https://go.microsoft.com/fwlink/?linkid=14202")] 
[ComVisibleAttribute(true)] 
public ref class UnmanagedMarshal sealed

/** @attribute SerializableAttribute() */ 
/** @attribute ObsoleteAttribute("An alternate API is available: Emit the MarshalAs custom attribute instead. https://go.microsoft.com/fwlink/?linkid=14202") */ 
/** @attribute ComVisibleAttribute(true) */ 
public final class UnmanagedMarshal

SerializableAttribute 
ObsoleteAttribute("An alternate API is available: Emit the MarshalAs custom attribute instead. https://go.microsoft.com/fwlink/?linkid=14202") 
ComVisibleAttribute(true) 
public final class UnmanagedMarshal

备注

提示

应用于此类的 HostProtectionAttribute 属性 (Attribute) 具有以下 Resources 属性 (Property) 值：MayLeakOnAbort。HostProtectionAttribute 不影响桌面应用程序（桌面应用程序一般通过双击图标，键入命令或在浏览器中输入 URL 启动）。有关更多信息，请参见 HostProtectionAttribute 类或 SQL Server 编程和宿主保护属性。

该代码示例演示了解决此过时类型的方法。

封送处理是对参数进行打包和解包以便可以发生远程过程调用的过程。封送处理期间，当托管类型的格式不同于相应的非托管类型的格式时，字段可能要经历格式转换。例如，可能要将 String 类型作为非托管 BSTR 进行封送。运行库自动处理某些格式转换。若要重写默认行为，必须使用 UnmanagedMarshal 类定义格式转换。

示例

下面的代码示例演示了过时 UnmanagedMarshal 类型的替代代码。该示例发出一个名为 EmitMarshalAs.dll 的单模块程序集，其中包含一个名为 Sample 的类型。该类型具有名为 Test 的方法，具有一个类型为 String 的参数。该代码示例将具有 UnmanagedType.BStr 的 MarshalAsAttribute 应用于参数。

可以使用 MSIL 反汇编程序 (Ildasm.exe) 来检查发出的程序集，并观察该参数是否标记为 marshal(bstr)。

Imports System
Imports System.Reflection
Imports System.Reflection.Emit
Imports System.Runtime.InteropServices

Public Class Example

    Public Shared Sub Main()

        Dim myDomain As AppDomain = AppDomain.CurrentDomain
        Dim myAsmName As New AssemblyName("EmitMarshalAs")

        Dim myAssembly As AssemblyBuilder = _
            myDomain.DefineDynamicAssembly(myAsmName, _
                AssemblyBuilderAccess.RunAndSave)

        Dim myModule As ModuleBuilder = _
            myAssembly.DefineDynamicModule(myAsmName.Name, _
                myAsmName.Name & ".dll")

        Dim myType As TypeBuilder = _
            myModule.DefineType("Sample", TypeAttributes.Public)
        
        Dim myMethod As MethodBuilder = _
            myType.DefineMethod("Test", MethodAttributes.Public, _
                Nothing, new Type() { GetType(String) })


        ' Get a parameter builder for the parameter that needs the 
        ' attribute, using the HasFieldMarshal attribute. In this
        ' example, the parameter is at position 0 and has the name
        ' "arg".
        Dim pb As ParameterBuilder = _
            myMethod.DefineParameter(0, _
               ParameterAttributes.HasFieldMarshal, "arg")

        ' Get the MarshalAsAttribute constructor that takes an
        ' argument of type UnmanagedType.
        '
        Dim ciParameters() As Type = { GetType(UnmanagedType) }
        Dim ci As ConstructorInfo = _
            GetType(MarshalAsAttribute).GetConstructor(ciParameters)

        ' Create a CustomAttributeBuilder representing the attribute,
        ' specifying the necessary unmanaged type. In this case, 
        ' UnmanagedType.BStr is specified.
        '
        Dim ciArguments() As Object = { UnmanagedType.BStr }
        Dim cabuilder As New CustomAttributeBuilder(ci, ciArguments)

        ' Apply the attribute to the parameter.
        '
        pb.SetCustomAttribute(cabuilder)


        ' Emit a dummy method body.
        Dim il As ILGenerator = myMethod.GetILGenerator()
        il.Emit(OpCodes.Ret)

        myType.CreateType()
        myAssembly.Save(myAsmName.Name & ".dll")

    End Sub

End Class

using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.InteropServices;

public class Example
{
    public static void Main()
    {
        AppDomain myDomain = AppDomain.CurrentDomain;
        AssemblyName myAsmName = new AssemblyName("EmitMarshalAs");

        AssemblyBuilder myAssembly = 
            myDomain.DefineDynamicAssembly(myAsmName, 
                AssemblyBuilderAccess.RunAndSave);

        ModuleBuilder myModule = 
            myAssembly.DefineDynamicModule(myAsmName.Name, 
               myAsmName.Name + ".dll");

        TypeBuilder myType = 
            myModule.DefineType("Sample", TypeAttributes.Public);

        MethodBuilder myMethod = 
            myType.DefineMethod("Test", MethodAttributes.Public,
                null, new Type[] { typeof(string) });


        // Get a parameter builder for the parameter that needs the 
        // attribute, using the HasFieldMarshal attribute. In this
        // example, the parameter is at position 0 and has the name
        // "arg".
        ParameterBuilder pb = 
            myMethod.DefineParameter(0, 
               ParameterAttributes.HasFieldMarshal, "arg");

        // Get the MarshalAsAttribute constructor that takes an
        // argument of type UnmanagedType.
        //
        ConstructorInfo ci = 
            typeof(MarshalAsAttribute).GetConstructor(
                new Type[] { typeof(UnmanagedType) });

        // Create a CustomAttributeBuilder representing the attribute,
        // specifying the necessary unmanaged type. In this case, 
        // UnmanagedType.BStr is specified.
        //
        CustomAttributeBuilder cabuilder = 
            new CustomAttributeBuilder(
                ci, new object[] { UnmanagedType.BStr });

        // Apply the attribute to the parameter.
        //
        pb.SetCustomAttribute(cabuilder);


        // Emit a dummy method body.
        ILGenerator il = myMethod.GetILGenerator();
        il.Emit(OpCodes.Ret);

        Type finished = myType.CreateType();
        myAssembly.Save(myAsmName.Name + ".dll");
    }
}

using namespace System;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
using namespace System::Runtime::InteropServices;

void main()
{
    AppDomain^ myDomain = AppDomain::CurrentDomain;
    AssemblyName^ myAsmName = gcnew AssemblyName("EmitMarshalAs");

    AssemblyBuilder^ myAssembly = 
        myDomain->DefineDynamicAssembly(myAsmName, 
            AssemblyBuilderAccess::RunAndSave);

    ModuleBuilder^ myModule = 
        myAssembly->DefineDynamicModule(myAsmName->Name, 
            myAsmName->Name + ".dll");
 
    TypeBuilder^ myType = 
        myModule->DefineType("Sample", TypeAttributes::Public);

    MethodBuilder^ myMethod = 
        myType->DefineMethod("Test", MethodAttributes::Public,
            nullptr, gcnew array<Type^> { String::typeid });


    // Get a parameter builder for the parameter that needs the 
    // attribute, using the HasFieldMarshal attribute. In this
    // example, the parameter is at position 0 and has the name
    // "arg".
    ParameterBuilder^ pb = 
        myMethod->DefineParameter(0, 
            ParameterAttributes::HasFieldMarshal, "arg");

    // Get the MarshalAsAttribute constructor that takes an
    // argument of type UnmanagedType.
    //
    //Type^ maattrType = MarshalAsAttribute::typeid;
    ConstructorInfo^ ci = 
        (MarshalAsAttribute::typeid)->GetConstructor(
            gcnew array<Type^> { UnmanagedType::typeid });

    // Create a CustomAttributeBuilder representing the attribute,
    // specifying the necessary unmanaged type. In this case, 
    // UnmanagedType.BStr is specified.
    //
    CustomAttributeBuilder^ cabuilder = 
        gcnew CustomAttributeBuilder(
            ci, gcnew array<Object^> { UnmanagedType::BStr });

    // Apply the attribute to the parameter.
    //
    pb->SetCustomAttribute(cabuilder);


    ILGenerator^ il = myMethod->GetILGenerator();
    il->Emit(OpCodes::Ret);

    Type^ finished = myType->CreateType();
    myAssembly->Save(myAsmName->Name + ".dll");
}

继承层次结构

System.Object
  System.Reflection.Emit.UnmanagedMarshal

线程安全

此类型的任何公共静态（Visual Basic 中的 Shared）成员都是线程安全的，但不保证所有实例成员都是线程安全的。

平台

Windows 98、Windows 2000 SP4、Windows Millennium Edition、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition

.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。

版本信息

.NET Framework

受以下版本支持：1.0、1.1
在 2.0 中过时（编译器警告）

请参见

参考

UnmanagedMarshal 成员
System.Reflection.Emit 命名空间
Type
UnmanagedType
Guid