ConstructorBuilder 类
定义并表示动态类的构造函数。
**命名空间:**System.Reflection.Emit
**程序集:**mscorlib（在 mscorlib.dll 中）
语法
声明
<ClassInterfaceAttribute(ClassInterfaceType.None)> _
<ComVisibleAttribute(True)> _
Public NotInheritable Class ConstructorBuilder
Inherits ConstructorInfo
Implements _ConstructorBuilder
用法
Dim instance As ConstructorBuilder
[ClassInterfaceAttribute(ClassInterfaceType.None)]
[ComVisibleAttribute(true)]
public sealed class ConstructorBuilder : ConstructorInfo, _ConstructorBuilder
[ClassInterfaceAttribute(ClassInterfaceType::None)]
[ComVisibleAttribute(true)]
public ref class ConstructorBuilder sealed : public ConstructorInfo, _ConstructorBuilder
/** @attribute ClassInterfaceAttribute(ClassInterfaceType.None) */
/** @attribute ComVisibleAttribute(true) */
public final class ConstructorBuilder extends ConstructorInfo implements _ConstructorBuilder
ClassInterfaceAttribute(ClassInterfaceType.None)
ComVisibleAttribute(true)
public final class ConstructorBuilder extends ConstructorInfo implements _ConstructorBuilder
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（此类应用程序通常通过双击图标、键入命令或者在浏览器中输入 URL 来启动）。有关更多信息，请参见 HostProtectionAttribute 类或 SQL Server 编程和宿主保护属性。
ConstructorBuilder 用于充分描述 Microsoft 中间语言 (MSIL) 中的构造函数，包括名称、属性、签名和构造函数体。它与 TypeBuilder 类一起使用以在运行时创建类。调用 DefineConstructor 以获取 ConstructorBuilder 的实例。
下面的代码示例阐释了 ConstructorBuilder 的上下文用法。
Imports System
Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit
_
Class TestCtorBuilder
Public Shared Function DynamicPointTypeGen() As Type
Dim pointType As Type = Nothing
Dim ctorParams() As Type = {GetType(Integer), GetType(Integer), GetType(Integer)}
Dim myDomain As AppDomain = Thread.GetDomain()
Dim myAsmName As New AssemblyName()
myAsmName.Name = "MyDynamicAssembly"
Dim myAsmBuilder As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, AssemblyBuilderAccess.RunAndSave)
Dim pointModule As ModuleBuilder = myAsmBuilder.DefineDynamicModule("PointModule", "Point.dll")
Dim pointTypeBld As TypeBuilder = pointModule.DefineType("Point", TypeAttributes.Public)
Dim xField As FieldBuilder = pointTypeBld.DefineField("x", GetType(Integer), FieldAttributes.Public)
Dim yField As FieldBuilder = pointTypeBld.DefineField("y", GetType(Integer), FieldAttributes.Public)
Dim zField As FieldBuilder = pointTypeBld.DefineField("z", GetType(Integer), FieldAttributes.Public)
Dim objType As Type = Type.GetType("System.Object")
Dim objCtor As ConstructorInfo = objType.GetConstructor(New Type() {})
Dim pointCtor As ConstructorBuilder = pointTypeBld.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, ctorParams)
Dim ctorIL As ILGenerator = pointCtor.GetILGenerator()
' NOTE: ldarg.0 holds the "this" reference - ldarg.1, ldarg.2, and ldarg.3
' hold the actual passed parameters. ldarg.0 is used by instance methods
' to hold a reference to the current calling object instance. Static methods
' do not use arg.0, since they are not instantiated and hence no reference
' is needed to distinguish them.
ctorIL.Emit(OpCodes.Ldarg_0)
' Here, we wish to create an instance of System.Object by invoking its
' constructor, as specified above.
ctorIL.Emit(OpCodes.Call, objCtor)
' Now, we'll load the current instance ref in arg 0, along
' with the value of parameter "x" stored in arg 1, into stfld.
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_1)
ctorIL.Emit(OpCodes.Stfld, xField)
' Now, we store arg 2 "y" in the current instance with stfld.
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_2)
ctorIL.Emit(OpCodes.Stfld, yField)
' Last of all, arg 3 "z" gets stored in the current instance.
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_3)
ctorIL.Emit(OpCodes.Stfld, zField)
' Our work complete, we return.
ctorIL.Emit(OpCodes.Ret)
' Now, let's create three very simple methods so we can see our fields.
Dim mthdNames() As String = {"GetX", "GetY", "GetZ"}
Dim mthdName As String
For Each mthdName In mthdNames
Dim getFieldMthd As MethodBuilder = pointTypeBld.DefineMethod(mthdName, MethodAttributes.Public, GetType(Integer), Nothing)
Dim mthdIL As ILGenerator = getFieldMthd.GetILGenerator()
mthdIL.Emit(OpCodes.Ldarg_0)
Select Case mthdName
Case "GetX"
mthdIL.Emit(OpCodes.Ldfld, xField)
Case "GetY"
mthdIL.Emit(OpCodes.Ldfld, yField)
Case "GetZ"
mthdIL.Emit(OpCodes.Ldfld, zField)
End Select
mthdIL.Emit(OpCodes.Ret)
Next mthdName
' Finally, we create the type.
pointType = pointTypeBld.CreateType()
' Let's save it, just for posterity.
myAsmBuilder.Save("Point.dll")
Return pointType
End Function 'DynamicPointTypeGen
Public Shared Sub Main()
Dim myDynamicType As Type = Nothing
Dim aPoint As Object = Nothing
Dim aPtypes() As Type = {GetType(Integer), GetType(Integer), GetType(Integer)}
Dim aPargs() As Object = {4, 5, 6}
' Call the method to build our dynamic class.
myDynamicType = DynamicPointTypeGen()
Console.WriteLine("Some information about my new Type '{0}':", myDynamicType.FullName)
Console.WriteLine("Assembly: '{0}'", myDynamicType.Assembly)
Console.WriteLine("Attributes: '{0}'", myDynamicType.Attributes)
Console.WriteLine("Module: '{0}'", myDynamicType.Module)
Console.WriteLine("Members: ")
Dim member As MemberInfo
For Each member In myDynamicType.GetMembers()
Console.WriteLine("-- {0} {1};", member.MemberType, member.Name)
Next member
Console.WriteLine("---")
' Let's take a look at the constructor we created.
Dim myDTctor As ConstructorInfo = myDynamicType.GetConstructor(aPtypes)
Console.WriteLine("Constructor: {0};", myDTctor.ToString())
Console.WriteLine("---")
' Now, we get to use our dynamically-created class by invoking the constructor.
aPoint = myDTctor.Invoke(aPargs)
Console.WriteLine("aPoint is type {0}.", aPoint.GetType())
' Finally, let's reflect on the instance of our new type - aPoint - and
' make sure everything proceeded according to plan.
Console.WriteLine("aPoint.x = {0}", myDynamicType.InvokeMember("GetX", BindingFlags.InvokeMethod, Nothing, aPoint, New Object() {}))
Console.WriteLine("aPoint.y = {0}", myDynamicType.InvokeMember("GetY", BindingFlags.InvokeMethod, Nothing, aPoint, New Object() {}))
Console.WriteLine("aPoint.z = {0}", myDynamicType.InvokeMember("GetZ", BindingFlags.InvokeMethod, Nothing, aPoint, New Object() {}))
End Sub 'Main
End Class 'TestCtorBuilder
' +++ OUTPUT +++
' Some information about my new Type 'Point':
' Assembly: 'MyDynamicAssembly, Version=0.0.0.0'
' Attributes: 'AutoLayout, AnsiClass, NotPublic, Public'
' Module: 'PointModule'
' Members:
' -- Field x;
' -- Field y;
' -- Field z;
' -- Method GetHashCode;
' -- Method Equals;
' -- Method ToString;
' -- Method GetType;
' -- Constructor .ctor;
' ---
' Constructor: Void .ctor(Int32, Int32, Int32);
' ---
' aPoint is type Point.
' aPoint.x = 4
' aPoint.y = 5
' aPoint.z = 6
using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;
class TestCtorBuilder {
public static Type DynamicPointTypeGen() {
Type pointType = null;
Type[] ctorParams = new Type[] {typeof(int),
typeof(int),
typeof(int)};
AppDomain myDomain = Thread.GetDomain();
AssemblyName myAsmName = new AssemblyName();
myAsmName.Name = "MyDynamicAssembly";
AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
myAsmName,
AssemblyBuilderAccess.RunAndSave);
ModuleBuilder pointModule = myAsmBuilder.DefineDynamicModule("PointModule",
"Point.dll");
TypeBuilder pointTypeBld = pointModule.DefineType("Point",
TypeAttributes.Public);
FieldBuilder xField = pointTypeBld.DefineField("x", typeof(int),
FieldAttributes.Public);
FieldBuilder yField = pointTypeBld.DefineField("y", typeof(int),
FieldAttributes.Public);
FieldBuilder zField = pointTypeBld.DefineField("z", typeof(int),
FieldAttributes.Public);
Type objType = Type.GetType("System.Object");
ConstructorInfo objCtor = objType.GetConstructor(new Type[0]);
ConstructorBuilder pointCtor = pointTypeBld.DefineConstructor(
MethodAttributes.Public,
CallingConventions.Standard,
ctorParams);
ILGenerator ctorIL = pointCtor.GetILGenerator();
// NOTE: ldarg.0 holds the "this" reference - ldarg.1, ldarg.2, and ldarg.3
// hold the actual passed parameters. ldarg.0 is used by instance methods
// to hold a reference to the current calling object instance. Static methods
// do not use arg.0, since they are not instantiated and hence no reference
// is needed to distinguish them.
ctorIL.Emit(OpCodes.Ldarg_0);
// Here, we wish to create an instance of System.Object by invoking its
// constructor, as specified above.
ctorIL.Emit(OpCodes.Call, objCtor);
// Now, we'll load the current instance ref in arg 0, along
// with the value of parameter "x" stored in arg 1, into stfld.
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Ldarg_1);
ctorIL.Emit(OpCodes.Stfld, xField);
// Now, we store arg 2 "y" in the current instance with stfld.
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Ldarg_2);
ctorIL.Emit(OpCodes.Stfld, yField);
// Last of all, arg 3 "z" gets stored in the current instance.
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Ldarg_3);
ctorIL.Emit(OpCodes.Stfld, zField);
// Our work complete, we return.
ctorIL.Emit(OpCodes.Ret);
// Now, let's create three very simple methods so we can see our fields.
string[] mthdNames = new string[] {"GetX", "GetY", "GetZ"};
foreach (string mthdName in mthdNames) {
MethodBuilder getFieldMthd = pointTypeBld.DefineMethod(
mthdName,
MethodAttributes.Public,
typeof(int),
null);
ILGenerator mthdIL = getFieldMthd.GetILGenerator();
mthdIL.Emit(OpCodes.Ldarg_0);
switch (mthdName) {
case "GetX": mthdIL.Emit(OpCodes.Ldfld, xField);
break;
case "GetY": mthdIL.Emit(OpCodes.Ldfld, yField);
break;
case "GetZ": mthdIL.Emit(OpCodes.Ldfld, zField);
break;
}
mthdIL.Emit(OpCodes.Ret);
}
// Finally, we create the type.
pointType = pointTypeBld.CreateType();
// Let's save it, just for posterity.
myAsmBuilder.Save("Point.dll");
return pointType;
}
public static void Main() {
Type myDynamicType = null;
object aPoint = null;
Type[] aPtypes = new Type[] {typeof(int), typeof(int), typeof(int)};
object[] aPargs = new object[] {4, 5, 6};
// Call the method to build our dynamic class.
myDynamicType = DynamicPointTypeGen();
Console.WriteLine("Some information about my new Type '{0}':",
myDynamicType.FullName);
Console.WriteLine("Assembly: '{0}'", myDynamicType.Assembly);
Console.WriteLine("Attributes: '{0}'", myDynamicType.Attributes);
Console.WriteLine("Module: '{0}'", myDynamicType.Module);
Console.WriteLine("Members: ");
foreach (MemberInfo member in myDynamicType.GetMembers()) {
Console.WriteLine("-- {0} {1};", member.MemberType, member.Name);
}
Console.WriteLine("---");
// Let's take a look at the constructor we created.
ConstructorInfo myDTctor = myDynamicType.GetConstructor(aPtypes);
Console.WriteLine("Constructor: {0};", myDTctor.ToString());
Console.WriteLine("---");
// Now, we get to use our dynamically-created class by invoking the constructor.
aPoint = myDTctor.Invoke(aPargs);
Console.WriteLine("aPoint is type {0}.", aPoint.GetType());
// Finally, let's reflect on the instance of our new type - aPoint - and
// make sure everything proceeded according to plan.
Console.WriteLine("aPoint.x = {0}",
myDynamicType.InvokeMember("GetX",
BindingFlags.InvokeMethod,
null,
aPoint,
new object[0]));
Console.WriteLine("aPoint.y = {0}",
myDynamicType.InvokeMember("GetY",
BindingFlags.InvokeMethod,
null,
aPoint,
new object[0]));
Console.WriteLine("aPoint.z = {0}",
myDynamicType.InvokeMember("GetZ",
BindingFlags.InvokeMethod,
null,
aPoint,
new object[0]));
// +++ OUTPUT +++
// Some information about my new Type 'Point':
// Assembly: 'MyDynamicAssembly, Version=0.0.0.0'
// Attributes: 'AutoLayout, AnsiClass, NotPublic, Public'
// Module: 'PointModule'
// Members:
// -- Field x;
// -- Field y;
// -- Field z;
// -- Method GetHashCode;
// -- Method Equals;
// -- Method ToString;
// -- Method GetType;
// -- Constructor .ctor;
// ---
// Constructor: Void .ctor(Int32, Int32, Int32);
// ---
// aPoint is type Point.
// aPoint.x = 4
// aPoint.y = 5
// aPoint.z = 6
}
}
using namespace System;
using namespace System::Threading;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
Type^ DynamicPointTypeGen()
{
Type^ pointType = nullptr;
array<Type^>^temp0 = {int::typeid,int::typeid,int::typeid};
array<Type^>^ctorParams = temp0;
AppDomain^ myDomain = Thread::GetDomain();
AssemblyName^ myAsmName = gcnew AssemblyName;
myAsmName->Name = "MyDynamicAssembly";
AssemblyBuilder^ myAsmBuilder = myDomain->DefineDynamicAssembly( myAsmName, AssemblyBuilderAccess::RunAndSave );
ModuleBuilder^ pointModule = myAsmBuilder->DefineDynamicModule( "PointModule", "Point.dll" );
TypeBuilder^ pointTypeBld = pointModule->DefineType( "Point", TypeAttributes::Public );
FieldBuilder^ xField = pointTypeBld->DefineField( "x", int::typeid, FieldAttributes::Public );
FieldBuilder^ yField = pointTypeBld->DefineField( "y", int::typeid, FieldAttributes::Public );
FieldBuilder^ zField = pointTypeBld->DefineField( "z", int::typeid, FieldAttributes::Public );
Type^ objType = Type::GetType( "System.Object" );
ConstructorInfo^ objCtor = objType->GetConstructor( gcnew array<Type^>(0) );
ConstructorBuilder^ pointCtor = pointTypeBld->DefineConstructor( MethodAttributes::Public, CallingConventions::Standard, ctorParams );
ILGenerator^ ctorIL = pointCtor->GetILGenerator();
// NOTE: ldarg.0 holds the "this" reference - ldarg.1, ldarg.2, and ldarg.3
// hold the actual passed parameters. ldarg.0 is used by instance methods
// to hold a reference to the current calling bject instance. Static methods
// do not use arg.0, since they are not instantiated and hence no reference
// is needed to distinguish them.
ctorIL->Emit( OpCodes::Ldarg_0 );
// Here, we wish to create an instance of System::Object by invoking its
// constructor, as specified above.
ctorIL->Emit( OpCodes::Call, objCtor );
// Now, we'll load the current instance in arg 0, along
// with the value of parameter "x" stored in arg 1, into stfld.
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Ldarg_1 );
ctorIL->Emit( OpCodes::Stfld, xField );
// Now, we store arg 2 "y" in the current instance with stfld.
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Ldarg_2 );
ctorIL->Emit( OpCodes::Stfld, yField );
// Last of all, arg 3 "z" gets stored in the current instance.
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Ldarg_3 );
ctorIL->Emit( OpCodes::Stfld, zField );
// Our work complete, we return.
ctorIL->Emit( OpCodes::Ret );
// Now, let's create three very simple methods so we can see our fields.
array<String^>^temp1 = {"GetX","GetY","GetZ"};
array<String^>^mthdNames = temp1;
System::Collections::IEnumerator^ myEnum = mthdNames->GetEnumerator();
while ( myEnum->MoveNext() )
{
String^ mthdName = safe_cast<String^>(myEnum->Current);
MethodBuilder^ getFieldMthd = pointTypeBld->DefineMethod( mthdName, MethodAttributes::Public, int::typeid, nullptr );
ILGenerator^ mthdIL = getFieldMthd->GetILGenerator();
mthdIL->Emit( OpCodes::Ldarg_0 );
if ( mthdName->Equals( "GetX" ) )
mthdIL->Emit( OpCodes::Ldfld, xField );
else
if ( mthdName->Equals( "GetY" ) )
mthdIL->Emit( OpCodes::Ldfld, yField );
else
if ( mthdName->Equals( "GetZ" ) )
mthdIL->Emit( OpCodes::Ldfld, zField );
mthdIL->Emit( OpCodes::Ret );
}
pointType = pointTypeBld->CreateType();
// Let's save it, just for posterity.
myAsmBuilder->Save( "Point.dll" );
return pointType;
}
int main()
{
Type^ myDynamicType = nullptr;
Object^ aPoint = nullptr;
array<Type^>^temp2 = {int::typeid,int::typeid,int::typeid};
array<Type^>^aPtypes = temp2;
array<Object^>^temp3 = {4,5,6};
array<Object^>^aPargs = temp3;
// Call the method to build our dynamic class.
myDynamicType = DynamicPointTypeGen();
Console::WriteLine( "Some information about my new Type '{0}':", myDynamicType->FullName );
Console::WriteLine( "Assembly: '{0}'", myDynamicType->Assembly );
Console::WriteLine( "Attributes: '{0}'", myDynamicType->Attributes );
Console::WriteLine( "Module: '{0}'", myDynamicType->Module );
Console::WriteLine( "Members: " );
System::Collections::IEnumerator^ myEnum = myDynamicType->GetMembers()->GetEnumerator();
while ( myEnum->MoveNext() )
{
MemberInfo^ member = safe_cast<MemberInfo^>(myEnum->Current);
Console::WriteLine( "-- {0} {1};", member->MemberType, member->Name );
}
Console::WriteLine( "---" );
// Let's take a look at the constructor we created.
ConstructorInfo^ myDTctor = myDynamicType->GetConstructor( aPtypes );
Console::WriteLine( "Constructor: {0};", myDTctor );
Console::WriteLine( "---" );
// Now, we get to use our dynamically-created class by invoking the constructor.
aPoint = myDTctor->Invoke( aPargs );
Console::WriteLine( "aPoint is type {0}.", aPoint->GetType() );
// Finally, let's reflect on the instance of our new type - aPoint - and
// make sure everything proceeded according to plan.
Console::WriteLine( "aPoint.x = {0}", myDynamicType->InvokeMember( "GetX", BindingFlags::InvokeMethod, nullptr, aPoint, gcnew array<Object^>(0) ) );
Console::WriteLine( "aPoint.y = {0}", myDynamicType->InvokeMember( "GetY", BindingFlags::InvokeMethod, nullptr, aPoint, gcnew array<Object^>(0) ) );
Console::WriteLine( "aPoint.z = {0}", myDynamicType->InvokeMember( "GetZ", BindingFlags::InvokeMethod, nullptr, aPoint, gcnew array<Object^>(0) ) );
// +++ OUTPUT +++
// Some information about my new Type 'Point':
// Assembly: 'MyDynamicAssembly, Version=0.0.0.0'
// Attributes: 'AutoLayout, AnsiClass, NotPublic, Public'
// Module: 'PointModule'
// Members:
// -- Field x;
// -- Field y;
// -- Field z;
// -- Method GetHashCode;
// -- Method Equals;
// -- Method ToString;
// -- Method GetType;
// -- Constructor .ctor;
// ---
// Constructor: Void .ctor(Int32, Int32, Int32);
// ---
// aPoint is type Point.
// aPoint.x = 4
// aPoint.y = 5
// aPoint.z = 6
}
继承层次结构
System.Object
System.Reflection.MemberInfo
System.Reflection.MethodBase
System.Reflection.ConstructorInfo
System.Reflection.Emit.ConstructorBuilder
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：2.0、1.1、1.0