ILGenerator.Emit 方法

参考

定义

命名空间:: System.Reflection.Emit

程序集:: System.Reflection.Emit.ILGeneration.dll

程序集:: mscorlib.dll

程序集:: netstandard.dll

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。

将指令放到实时 (JIT) 编译器的 Microsoft 中间语言 (MSIL) 流上。

重载

Emit(OpCode, Type)	将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，后跟给定类型的元数据令牌。
Emit(OpCode, String)	将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，后跟给定字符串的元数据令牌。
Emit(OpCode, Single)	将指定的指令和数值参数放到 Microsoft 中间语言 (MSIL) 指令流上。
Emit(OpCode, SByte)	将指定的指令和字符参数放到 Microsoft 中间语言 (MSIL) 指令流上。
Emit(OpCode, FieldInfo)	将指定字段的指定指令和元数据令牌放到 Microsoft 中间语言 (MSIL) 指令流上。
Emit(OpCode, SignatureHelper)	将指定的指令和签名令牌放到 Microsoft 中间语言 (MSIL) 指令流上。
Emit(OpCode, LocalBuilder)	将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，后跟给定局部变量的索引。
Emit(OpCode, Label[])	将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，并留出在完成修正时加上标签所需的空白。
Emit(OpCode, MethodInfo)	将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，后跟给定方法的元数据令牌。
Emit(OpCode, ConstructorInfo)	将指定构造函数的指定指令和元数据令牌放到 Microsoft 中间语言 (MSIL) 指令流上。
Emit(OpCode, Int64)	将指定的指令和数值参数放到 Microsoft 中间语言 (MSIL) 指令流上。
Emit(OpCode, Int32)	将指定的指令和数值参数放到 Microsoft 中间语言 (MSIL) 指令流上。
Emit(OpCode, Int16)	将指定的指令和数值参数放到 Microsoft 中间语言 (MSIL) 指令流上。
Emit(OpCode, Double)	将指定的指令和数值参数放到 Microsoft 中间语言 (MSIL) 指令流上。
Emit(OpCode, Byte)	将指定的指令和字符参数放到 Microsoft 中间语言 (MSIL) 指令流上。
Emit(OpCode)	将指定的指令放到指令流上。
Emit(OpCode, Label)	将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，并留出在完成修正时加上标签所需的空白。

Emit(OpCode, Type)

将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，后跟给定类型的元数据令牌。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, Type ^ cls);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, Type cls);

abstract member Emit : System.Reflection.Emit.OpCode * Type -> unit
override this.Emit : System.Reflection.Emit.OpCode * Type -> unit

Public Overridable Sub Emit (opcode As OpCode, cls As Type)

参数

opcode: OpCode

要放到流上的 MSIL 指令。

cls: Type

Type。

例外

ArgumentNullException

cls 为 null。

注解

指令值在枚举中 OpCodes 定义。将模块保存到可移植可执行文件 (PE) 文件时，可以在必要时修补令牌的位置 cls 。

适用于

Emit(OpCode, String)

将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，后跟给定字符串的元数据令牌。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, System::String ^ str);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, string str);

abstract member Emit : System.Reflection.Emit.OpCode * string -> unit
override this.Emit : System.Reflection.Emit.OpCode * string -> unit

Public Overridable Sub Emit (opcode As OpCode, str As String)

参数

opcode: OpCode

要发出到流的 MSIL 指令。

str: String

要发出的 String。

注解

指令值在枚举中 OpCodes 定义。如果模块保存到可移植可执行文件 (PE) 文件中，则会记录该位置 str 以供将来修复。

适用于

Emit(OpCode, Single)

将指定的指令和数值参数放到 Microsoft 中间语言 (MSIL) 指令流上。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, float arg);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, float arg);

abstract member Emit : System.Reflection.Emit.OpCode * single -> unit
override this.Emit : System.Reflection.Emit.OpCode * single -> unit

Public Overridable Sub Emit (opcode As OpCode, arg As Single)

参数

opcode: OpCode

要放到流上的 MSIL 指令。

arg: Single

紧接着该指令推到流中的 Single 参数。

注解

指令值在枚举中 OpCodes 定义。

适用于

Emit(OpCode, SByte)

重要

此 API 不符合 CLS。

将指定的指令和字符参数放到 Microsoft 中间语言 (MSIL) 指令流上。

public:
 void Emit(System::Reflection::Emit::OpCode opcode, System::SByte arg);

[System.CLSCompliant(false)]
public void Emit (System.Reflection.Emit.OpCode opcode, sbyte arg);

[<System.CLSCompliant(false)>]
member this.Emit : System.Reflection.Emit.OpCode * sbyte -> unit

Public Sub Emit (opcode As OpCode, arg As SByte)

参数

opcode: OpCode

要放到流上的 MSIL 指令。

arg: SByte

紧接着该指令推到流中的字符参数。

属性: CLSCompliantAttribute

注解

指令值在枚举中 OpCodes 定义。

适用于

Emit(OpCode, FieldInfo)

将指定字段的指定指令和元数据令牌放到 Microsoft 中间语言 (MSIL) 指令流上。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, System::Reflection::FieldInfo ^ field);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, System.Reflection.FieldInfo field);

abstract member Emit : System.Reflection.Emit.OpCode * System.Reflection.FieldInfo -> unit
override this.Emit : System.Reflection.Emit.OpCode * System.Reflection.FieldInfo -> unit

Public Overridable Sub Emit (opcode As OpCode, field As FieldInfo)

参数

opcode: OpCode

要发出到流的 MSIL 指令。

field: FieldInfo

表示字段的 FieldInfo。

注解

指令值在枚举中 OpCodes 定义。将模块保存到可移植可执行文件 (PE) 文件时，可以在必要时修补指令流的位置 field 。

适用于

Emit(OpCode, SignatureHelper)

将指定的指令和签名令牌放到 Microsoft 中间语言 (MSIL) 指令流上。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, System::Reflection::Emit::SignatureHelper ^ signature);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, System.Reflection.Emit.SignatureHelper signature);

abstract member Emit : System.Reflection.Emit.OpCode * System.Reflection.Emit.SignatureHelper -> unit
override this.Emit : System.Reflection.Emit.OpCode * System.Reflection.Emit.SignatureHelper -> unit

Public Overridable Sub Emit (opcode As OpCode, signature As SignatureHelper)

参数

opcode: OpCode

要发出到流的 MSIL 指令。

signature: SignatureHelper

用于构造签名令牌的帮助程序。

例外

ArgumentNullException

signature 为 null。

注解

指令值在枚举中 OpCodes 定义。

适用于

Emit(OpCode, LocalBuilder)

将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，后跟给定局部变量的索引。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, System::Reflection::Emit::LocalBuilder ^ local);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, System.Reflection.Emit.LocalBuilder local);

abstract member Emit : System.Reflection.Emit.OpCode * System.Reflection.Emit.LocalBuilder -> unit
override this.Emit : System.Reflection.Emit.OpCode * System.Reflection.Emit.LocalBuilder -> unit

Public Overridable Sub Emit (opcode As OpCode, local As LocalBuilder)

参数

opcode: OpCode

要发出到流的 MSIL 指令。

local: LocalBuilder

局部变量。

例外

ArgumentException

local 参数的父方法与此 ILGenerator 关联的方法不匹配。

ArgumentNullException

local 为 null。

InvalidOperationException

opcode 是单字节指令，并且 local 表示索引大于 Byte.MaxValue 的局部变量。

注解

指令值在枚举中 OpCodes 定义。

适用于

Emit(OpCode, Label[])

将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，并留出在完成修正时加上标签所需的空白。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, cli::array <System::Reflection::Emit::Label> ^ labels);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, System.Reflection.Emit.Label[] labels);

abstract member Emit : System.Reflection.Emit.OpCode * System.Reflection.Emit.Label[] -> unit
override this.Emit : System.Reflection.Emit.OpCode * System.Reflection.Emit.Label[] -> unit

Public Overridable Sub Emit (opcode As OpCode, labels As Label())

参数

opcode: OpCode

要发出到流的 MSIL 指令。

labels: Label[]

从此位置分支到的标签对象的数组。将使用所有标签。

例外

ArgumentNullException

con 为 null。此异常是 .NET Framework 4 中的新增功能。

示例

下面的代码示例演示了如何使用跳转表创建动态方法。跳转表是使用数组 Label生成的。

using namespace System;
using namespace System::Threading;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
Type^ BuildMyType()
{
   AppDomain^ myDomain = Thread::GetDomain();
   AssemblyName^ myAsmName = gcnew AssemblyName;
   myAsmName->Name = "MyDynamicAssembly";
   AssemblyBuilder^ myAsmBuilder = myDomain->DefineDynamicAssembly( myAsmName, AssemblyBuilderAccess::Run );
   ModuleBuilder^ myModBuilder = myAsmBuilder->DefineDynamicModule( "MyJumpTableDemo" );
   TypeBuilder^ myTypeBuilder = myModBuilder->DefineType( "JumpTableDemo", TypeAttributes::Public );
   array<Type^>^temp0 = {int::typeid};
   MethodBuilder^ myMthdBuilder = myTypeBuilder->DefineMethod( "SwitchMe", static_cast<MethodAttributes>(MethodAttributes::Public | MethodAttributes::Static), String::typeid, temp0 );
   ILGenerator^ myIL = myMthdBuilder->GetILGenerator();
   Label defaultCase = myIL->DefineLabel();
   Label endOfMethod = myIL->DefineLabel();
   
   // We are initializing our jump table. Note that the labels
   // will be placed later using the MarkLabel method.
   array<Label>^jumpTable = gcnew array<Label>(5);
   jumpTable[ 0 ] = myIL->DefineLabel();
   jumpTable[ 1 ] = myIL->DefineLabel();
   jumpTable[ 2 ] = myIL->DefineLabel();
   jumpTable[ 3 ] = myIL->DefineLabel();
   jumpTable[ 4 ] = myIL->DefineLabel();
   
   // arg0, the number we passed, is pushed onto the stack.
   // In this case, due to the design of the code sample,
   // the value pushed onto the stack happens to match the
   // index of the label (in IL terms, the index of the offset
   // in the jump table). If this is not the case, such as
   // when switching based on non-integer values, rules for the correspondence
   // between the possible case values and each index of the offsets
   // must be established outside of the ILGenerator::Emit calls,
   // much as a compiler would.
   myIL->Emit( OpCodes::Ldarg_0 );
   myIL->Emit( OpCodes::Switch, jumpTable );
   
   // Branch on default case
   myIL->Emit( OpCodes::Br_S, defaultCase );
   
   // Case arg0 = 0
   myIL->MarkLabel( jumpTable[ 0 ] );
   myIL->Emit( OpCodes::Ldstr, "are no bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 1
   myIL->MarkLabel( jumpTable[ 1 ] );
   myIL->Emit( OpCodes::Ldstr, "is one banana" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 2
   myIL->MarkLabel( jumpTable[ 2 ] );
   myIL->Emit( OpCodes::Ldstr, "are two bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 3
   myIL->MarkLabel( jumpTable[ 3 ] );
   myIL->Emit( OpCodes::Ldstr, "are three bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 4
   myIL->MarkLabel( jumpTable[ 4 ] );
   myIL->Emit( OpCodes::Ldstr, "are four bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Default case
   myIL->MarkLabel( defaultCase );
   myIL->Emit( OpCodes::Ldstr, "are many bananas" );
   myIL->MarkLabel( endOfMethod );
   myIL->Emit( OpCodes::Ret );
   return myTypeBuilder->CreateType();
}

int main()
{
   Type^ myType = BuildMyType();
   Console::Write( "Enter an integer between 0 and 5: " );
   int theValue = Convert::ToInt32( Console::ReadLine() );
   Console::WriteLine( "---" );
   Object^ myInstance = Activator::CreateInstance( myType, gcnew array<Object^>(0) );
   array<Object^>^temp1 = {theValue};
   Console::WriteLine( "Yes, there {0} today!", myType->InvokeMember( "SwitchMe", BindingFlags::InvokeMethod, nullptr, myInstance, temp1 ) );
}


using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;

class DynamicJumpTableDemo

{

   public static Type BuildMyType()
   {
    AppDomain myDomain = Thread.GetDomain();
    AssemblyName myAsmName = new AssemblyName();
    myAsmName.Name = "MyDynamicAssembly";

    AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
                        myAsmName,
                        AssemblyBuilderAccess.Run);
    ModuleBuilder myModBuilder = myAsmBuilder.DefineDynamicModule(
                        "MyJumpTableDemo");

    TypeBuilder myTypeBuilder = myModBuilder.DefineType("JumpTableDemo",
                            TypeAttributes.Public);
    MethodBuilder myMthdBuilder = myTypeBuilder.DefineMethod("SwitchMe",
                             MethodAttributes.Public |
                             MethodAttributes.Static,
                                             typeof(string),
                                             new Type[] {typeof(int)});

    ILGenerator myIL = myMthdBuilder.GetILGenerator();

    Label defaultCase = myIL.DefineLabel();	
    Label endOfMethod = myIL.DefineLabel();	

    // We are initializing our jump table. Note that the labels
    // will be placed later using the MarkLabel method.

    Label[] jumpTable = new Label[] { myIL.DefineLabel(),
                      myIL.DefineLabel(),
                      myIL.DefineLabel(),
                      myIL.DefineLabel(),
                      myIL.DefineLabel() };

    // arg0, the number we passed, is pushed onto the stack.
    // In this case, due to the design of the code sample,
    // the value pushed onto the stack happens to match the
    // index of the label (in IL terms, the index of the offset
    // in the jump table). If this is not the case, such as
    // when switching based on non-integer values, rules for the correspondence
    // between the possible case values and each index of the offsets
    // must be established outside of the ILGenerator.Emit calls,
    // much as a compiler would.

    myIL.Emit(OpCodes.Ldarg_0);
    myIL.Emit(OpCodes.Switch, jumpTable);
    
    // Branch on default case
    myIL.Emit(OpCodes.Br_S, defaultCase);

    // Case arg0 = 0
    myIL.MarkLabel(jumpTable[0]);
    myIL.Emit(OpCodes.Ldstr, "are no bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 1
    myIL.MarkLabel(jumpTable[1]);
    myIL.Emit(OpCodes.Ldstr, "is one banana");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 2
    myIL.MarkLabel(jumpTable[2]);
    myIL.Emit(OpCodes.Ldstr, "are two bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 3
    myIL.MarkLabel(jumpTable[3]);
    myIL.Emit(OpCodes.Ldstr, "are three bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 4
    myIL.MarkLabel(jumpTable[4]);
    myIL.Emit(OpCodes.Ldstr, "are four bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Default case
    myIL.MarkLabel(defaultCase);
    myIL.Emit(OpCodes.Ldstr, "are many bananas");

    myIL.MarkLabel(endOfMethod);
    myIL.Emit(OpCodes.Ret);
    
    return myTypeBuilder.CreateType();
   }

   public static void Main()
   {
    Type myType = BuildMyType();
    
    Console.Write("Enter an integer between 0 and 5: ");
    int theValue = Convert.ToInt32(Console.ReadLine());

    Console.WriteLine("---");
    Object myInstance = Activator.CreateInstance(myType, new object[0]);	
    Console.WriteLine("Yes, there {0} today!", myType.InvokeMember("SwitchMe",
                               BindingFlags.InvokeMethod,
                               null,
                               myInstance,
                               new object[] {theValue}));
   }
}


Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit

 _

Class DynamicJumpTableDemo
   
   Public Shared Function BuildMyType() As Type

      Dim myDomain As AppDomain = Thread.GetDomain()
      Dim myAsmName As New AssemblyName()
      myAsmName.Name = "MyDynamicAssembly"
      
      Dim myAsmBuilder As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, _
                            AssemblyBuilderAccess.Run)
      Dim myModBuilder As ModuleBuilder = myAsmBuilder.DefineDynamicModule("MyJumpTableDemo")
      
      Dim myTypeBuilder As TypeBuilder = myModBuilder.DefineType("JumpTableDemo", _
                                 TypeAttributes.Public)
      Dim myMthdBuilder As MethodBuilder = myTypeBuilder.DefineMethod("SwitchMe", _
                        MethodAttributes.Public Or MethodAttributes.Static, _
                        GetType(String), New Type() {GetType(Integer)})
      
      Dim myIL As ILGenerator = myMthdBuilder.GetILGenerator()
      
      Dim defaultCase As Label = myIL.DefineLabel()
      Dim endOfMethod As Label = myIL.DefineLabel()
      
      ' We are initializing our jump table. Note that the labels
      ' will be placed later using the MarkLabel method. 

      Dim jumpTable() As Label = {myIL.DefineLabel(), _
                  myIL.DefineLabel(), _
                  myIL.DefineLabel(), _
                  myIL.DefineLabel(), _
                  myIL.DefineLabel()}
      
      ' arg0, the number we passed, is pushed onto the stack.
      ' In this case, due to the design of the code sample,
      ' the value pushed onto the stack happens to match the
      ' index of the label (in IL terms, the index of the offset
      ' in the jump table). If this is not the case, such as
      ' when switching based on non-integer values, rules for the correspondence
      ' between the possible case values and each index of the offsets
      ' must be established outside of the ILGenerator.Emit calls,
      ' much as a compiler would.

      myIL.Emit(OpCodes.Ldarg_0)
      myIL.Emit(OpCodes.Switch, jumpTable)
      
      ' Branch on default case
      myIL.Emit(OpCodes.Br_S, defaultCase)
      
      ' Case arg0 = 0
      myIL.MarkLabel(jumpTable(0))
      myIL.Emit(OpCodes.Ldstr, "are no bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 1
      myIL.MarkLabel(jumpTable(1))
      myIL.Emit(OpCodes.Ldstr, "is one banana")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 2
      myIL.MarkLabel(jumpTable(2))
      myIL.Emit(OpCodes.Ldstr, "are two bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 3
      myIL.MarkLabel(jumpTable(3))
      myIL.Emit(OpCodes.Ldstr, "are three bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 4
      myIL.MarkLabel(jumpTable(4))
      myIL.Emit(OpCodes.Ldstr, "are four bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Default case
      myIL.MarkLabel(defaultCase)
      myIL.Emit(OpCodes.Ldstr, "are many bananas")
      
      myIL.MarkLabel(endOfMethod)
      myIL.Emit(OpCodes.Ret)
      
      Return myTypeBuilder.CreateType()

   End Function 'BuildMyType
    
   
   Public Shared Sub Main()

      Dim myType As Type = BuildMyType()
      
      Console.Write("Enter an integer between 0 and 5: ")
      Dim theValue As Integer = Convert.ToInt32(Console.ReadLine())
      
      Console.WriteLine("---")
      Dim myInstance As [Object] = Activator.CreateInstance(myType, New Object() {})
      Console.WriteLine("Yes, there {0} today!", myType.InvokeMember("SwitchMe", _
                         BindingFlags.InvokeMethod, Nothing, _
                             myInstance, New Object() {theValue}))

   End Sub

End Class

注解

发出开关表。

指令值在枚举中 OpCodes 定义。

Labels are created using DefineLabel and their location within the stream is fixed by using MarkLabel. 如果使用单字节指令，则标签可以表示流中最多 127 字节的跳转。 opcode 必须表示分支指令。由于分支是相对指令， label 因此会在修复过程中替换为分支的正确偏移量。

适用于

Emit(OpCode, MethodInfo)

将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，后跟给定方法的元数据令牌。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, System::Reflection::MethodInfo ^ meth);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, System.Reflection.MethodInfo meth);

abstract member Emit : System.Reflection.Emit.OpCode * System.Reflection.MethodInfo -> unit
override this.Emit : System.Reflection.Emit.OpCode * System.Reflection.MethodInfo -> unit

Public Overridable Sub Emit (opcode As OpCode, meth As MethodInfo)

参数

opcode: OpCode

要发出到流的 MSIL 指令。

meth: MethodInfo

表示方法的 MethodInfo。

例外

ArgumentNullException

meth 为 null。

NotSupportedException

meth 为泛型方法，其 IsGenericMethodDefinition 属性为 false。

注解

指令值在枚举中 OpCodes 定义。

将模块保存到可移植可执行文件 (PE) 文件时，可以在必要时修补指令流的位置 meth 。

如果 meth 表示泛型方法，则它必须是泛型方法定义。也就是说，其 MethodInfo.IsGenericMethodDefinition 属性必须是 true。

适用于

Emit(OpCode, ConstructorInfo)

将指定构造函数的指定指令和元数据令牌放到 Microsoft 中间语言 (MSIL) 指令流上。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, System::Reflection::ConstructorInfo ^ con);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, System.Reflection.ConstructorInfo con);

[System.Runtime.InteropServices.ComVisible(true)]
public virtual void Emit (System.Reflection.Emit.OpCode opcode, System.Reflection.ConstructorInfo con);

abstract member Emit : System.Reflection.Emit.OpCode * System.Reflection.ConstructorInfo -> unit
override this.Emit : System.Reflection.Emit.OpCode * System.Reflection.ConstructorInfo -> unit

[<System.Runtime.InteropServices.ComVisible(true)>]
abstract member Emit : System.Reflection.Emit.OpCode * System.Reflection.ConstructorInfo -> unit
override this.Emit : System.Reflection.Emit.OpCode * System.Reflection.ConstructorInfo -> unit

Public Overridable Sub Emit (opcode As OpCode, con As ConstructorInfo)

参数

opcode: OpCode

要发出到流的 MSIL 指令。

con: ConstructorInfo

表示构造函数的 ConstructorInfo。

属性: ComVisibleAttribute

例外

ArgumentNullException

con 为 null。此异常是 .NET Framework 4 中的新增功能。

注解

指令值在枚举中 OpCodes 定义。

将模块保存到可移植可执行文件 (PE) 文件时，可以在必要时修补指令流的位置 con 。

适用于

Emit(OpCode, Int64)

将指定的指令和数值参数放到 Microsoft 中间语言 (MSIL) 指令流上。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, long arg);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, long arg);

abstract member Emit : System.Reflection.Emit.OpCode * int64 -> unit
override this.Emit : System.Reflection.Emit.OpCode * int64 -> unit

Public Overridable Sub Emit (opcode As OpCode, arg As Long)

参数

opcode: OpCode

要放到流上的 MSIL 指令。

arg: Int64

紧接着该指令推到流中的数字参数。

注解

指令值在枚举中 OpCodes 定义。

适用于

Emit(OpCode, Int32)

将指定的指令和数值参数放到 Microsoft 中间语言 (MSIL) 指令流上。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, int arg);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, int arg);

abstract member Emit : System.Reflection.Emit.OpCode * int -> unit
override this.Emit : System.Reflection.Emit.OpCode * int -> unit

Public Overridable Sub Emit (opcode As OpCode, arg As Integer)

参数

opcode: OpCode

要放到流上的 MSIL 指令。

arg: Int32

紧接着该指令推到流中的数字参数。

注解

指令值在枚举中 OpCodes 定义。

适用于

Emit(OpCode, Int16)

将指定的指令和数值参数放到 Microsoft 中间语言 (MSIL) 指令流上。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, short arg);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, short arg);

abstract member Emit : System.Reflection.Emit.OpCode * int16 -> unit
override this.Emit : System.Reflection.Emit.OpCode * int16 -> unit

Public Overridable Sub Emit (opcode As OpCode, arg As Short)

参数

opcode: OpCode

要发出到流的 MSIL 指令。

arg: Int16

紧接着该指令推到流中的 Int 参数。

注解

指令值在枚举中 OpCodes 定义。

适用于

Emit(OpCode, Double)

将指定的指令和数值参数放到 Microsoft 中间语言 (MSIL) 指令流上。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, double arg);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, double arg);

abstract member Emit : System.Reflection.Emit.OpCode * double -> unit
override this.Emit : System.Reflection.Emit.OpCode * double -> unit

Public Overridable Sub Emit (opcode As OpCode, arg As Double)

参数

opcode: OpCode

要放到流上的 MSIL 指令。在 OpCodes 枚举中定义。

arg: Double

紧接着该指令推到流中的数字参数。

注解

指令值在枚举中 OpCodes 定义。

适用于

Emit(OpCode, Byte)

将指定的指令和字符参数放到 Microsoft 中间语言 (MSIL) 指令流上。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, System::Byte arg);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, byte arg);

abstract member Emit : System.Reflection.Emit.OpCode * byte -> unit
override this.Emit : System.Reflection.Emit.OpCode * byte -> unit

Public Overridable Sub Emit (opcode As OpCode, arg As Byte)

参数

opcode: OpCode

要放到流上的 MSIL 指令。

arg: Byte

紧接着该指令推到流中的字符参数。

注解

指令值在枚举中 OpCodes 定义。

适用于

Emit(OpCode)

将指定的指令放到指令流上。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode);

public virtual void Emit (System.Reflection.Emit.OpCode opcode);

abstract member Emit : System.Reflection.Emit.OpCode -> unit
override this.Emit : System.Reflection.Emit.OpCode -> unit

Public Overridable Sub Emit (opcode As OpCode)

参数

opcode: OpCode

要放到流上的 Microsoft 中间语言 (MSIL) 指令。

示例

下面的代码示例演示如何通过 Emit 实例 ILGenerator生成 MSIL 输出。

using namespace System;
using namespace System::Threading;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
Type^ BuildMyType()
{
   AppDomain^ myDomain = Thread::GetDomain();
   AssemblyName^ myAsmName = gcnew AssemblyName;
   myAsmName->Name = "MyDynamicAssembly";
   AssemblyBuilder^ myAsmBuilder = myDomain->DefineDynamicAssembly( myAsmName, AssemblyBuilderAccess::Run );
   ModuleBuilder^ myModBuilder = myAsmBuilder->DefineDynamicModule( "MyJumpTableDemo" );
   TypeBuilder^ myTypeBuilder = myModBuilder->DefineType( "JumpTableDemo", TypeAttributes::Public );
   array<Type^>^temp0 = {int::typeid};
   MethodBuilder^ myMthdBuilder = myTypeBuilder->DefineMethod( "SwitchMe", static_cast<MethodAttributes>(MethodAttributes::Public | MethodAttributes::Static), String::typeid, temp0 );
   ILGenerator^ myIL = myMthdBuilder->GetILGenerator();
   Label defaultCase = myIL->DefineLabel();
   Label endOfMethod = myIL->DefineLabel();
   
   // We are initializing our jump table. Note that the labels
   // will be placed later using the MarkLabel method.
   array<Label>^jumpTable = gcnew array<Label>(5);
   jumpTable[ 0 ] = myIL->DefineLabel();
   jumpTable[ 1 ] = myIL->DefineLabel();
   jumpTable[ 2 ] = myIL->DefineLabel();
   jumpTable[ 3 ] = myIL->DefineLabel();
   jumpTable[ 4 ] = myIL->DefineLabel();
   
   // arg0, the number we passed, is pushed onto the stack.
   // In this case, due to the design of the code sample,
   // the value pushed onto the stack happens to match the
   // index of the label (in IL terms, the index of the offset
   // in the jump table). If this is not the case, such as
   // when switching based on non-integer values, rules for the correspondence
   // between the possible case values and each index of the offsets
   // must be established outside of the ILGenerator::Emit calls,
   // much as a compiler would.
   myIL->Emit( OpCodes::Ldarg_0 );
   myIL->Emit( OpCodes::Switch, jumpTable );
   
   // Branch on default case
   myIL->Emit( OpCodes::Br_S, defaultCase );
   
   // Case arg0 = 0
   myIL->MarkLabel( jumpTable[ 0 ] );
   myIL->Emit( OpCodes::Ldstr, "are no bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 1
   myIL->MarkLabel( jumpTable[ 1 ] );
   myIL->Emit( OpCodes::Ldstr, "is one banana" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 2
   myIL->MarkLabel( jumpTable[ 2 ] );
   myIL->Emit( OpCodes::Ldstr, "are two bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 3
   myIL->MarkLabel( jumpTable[ 3 ] );
   myIL->Emit( OpCodes::Ldstr, "are three bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 4
   myIL->MarkLabel( jumpTable[ 4 ] );
   myIL->Emit( OpCodes::Ldstr, "are four bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Default case
   myIL->MarkLabel( defaultCase );
   myIL->Emit( OpCodes::Ldstr, "are many bananas" );
   myIL->MarkLabel( endOfMethod );
   myIL->Emit( OpCodes::Ret );
   return myTypeBuilder->CreateType();
}

int main()
{
   Type^ myType = BuildMyType();
   Console::Write( "Enter an integer between 0 and 5: " );
   int theValue = Convert::ToInt32( Console::ReadLine() );
   Console::WriteLine( "---" );
   Object^ myInstance = Activator::CreateInstance( myType, gcnew array<Object^>(0) );
   array<Object^>^temp1 = {theValue};
   Console::WriteLine( "Yes, there {0} today!", myType->InvokeMember( "SwitchMe", BindingFlags::InvokeMethod, nullptr, myInstance, temp1 ) );
}


using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;

class DynamicJumpTableDemo

{

   public static Type BuildMyType()
   {
    AppDomain myDomain = Thread.GetDomain();
    AssemblyName myAsmName = new AssemblyName();
    myAsmName.Name = "MyDynamicAssembly";

    AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
                        myAsmName,
                        AssemblyBuilderAccess.Run);
    ModuleBuilder myModBuilder = myAsmBuilder.DefineDynamicModule(
                        "MyJumpTableDemo");

    TypeBuilder myTypeBuilder = myModBuilder.DefineType("JumpTableDemo",
                            TypeAttributes.Public);
    MethodBuilder myMthdBuilder = myTypeBuilder.DefineMethod("SwitchMe",
                             MethodAttributes.Public |
                             MethodAttributes.Static,
                                             typeof(string),
                                             new Type[] {typeof(int)});

    ILGenerator myIL = myMthdBuilder.GetILGenerator();

    Label defaultCase = myIL.DefineLabel();	
    Label endOfMethod = myIL.DefineLabel();	

    // We are initializing our jump table. Note that the labels
    // will be placed later using the MarkLabel method.

    Label[] jumpTable = new Label[] { myIL.DefineLabel(),
                      myIL.DefineLabel(),
                      myIL.DefineLabel(),
                      myIL.DefineLabel(),
                      myIL.DefineLabel() };

    // arg0, the number we passed, is pushed onto the stack.
    // In this case, due to the design of the code sample,
    // the value pushed onto the stack happens to match the
    // index of the label (in IL terms, the index of the offset
    // in the jump table). If this is not the case, such as
    // when switching based on non-integer values, rules for the correspondence
    // between the possible case values and each index of the offsets
    // must be established outside of the ILGenerator.Emit calls,
    // much as a compiler would.

    myIL.Emit(OpCodes.Ldarg_0);
    myIL.Emit(OpCodes.Switch, jumpTable);
    
    // Branch on default case
    myIL.Emit(OpCodes.Br_S, defaultCase);

    // Case arg0 = 0
    myIL.MarkLabel(jumpTable[0]);
    myIL.Emit(OpCodes.Ldstr, "are no bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 1
    myIL.MarkLabel(jumpTable[1]);
    myIL.Emit(OpCodes.Ldstr, "is one banana");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 2
    myIL.MarkLabel(jumpTable[2]);
    myIL.Emit(OpCodes.Ldstr, "are two bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 3
    myIL.MarkLabel(jumpTable[3]);
    myIL.Emit(OpCodes.Ldstr, "are three bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 4
    myIL.MarkLabel(jumpTable[4]);
    myIL.Emit(OpCodes.Ldstr, "are four bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Default case
    myIL.MarkLabel(defaultCase);
    myIL.Emit(OpCodes.Ldstr, "are many bananas");

    myIL.MarkLabel(endOfMethod);
    myIL.Emit(OpCodes.Ret);
    
    return myTypeBuilder.CreateType();
   }

   public static void Main()
   {
    Type myType = BuildMyType();
    
    Console.Write("Enter an integer between 0 and 5: ");
    int theValue = Convert.ToInt32(Console.ReadLine());

    Console.WriteLine("---");
    Object myInstance = Activator.CreateInstance(myType, new object[0]);	
    Console.WriteLine("Yes, there {0} today!", myType.InvokeMember("SwitchMe",
                               BindingFlags.InvokeMethod,
                               null,
                               myInstance,
                               new object[] {theValue}));
   }
}


Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit

 _

Class DynamicJumpTableDemo
   
   Public Shared Function BuildMyType() As Type

      Dim myDomain As AppDomain = Thread.GetDomain()
      Dim myAsmName As New AssemblyName()
      myAsmName.Name = "MyDynamicAssembly"
      
      Dim myAsmBuilder As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, _
                            AssemblyBuilderAccess.Run)
      Dim myModBuilder As ModuleBuilder = myAsmBuilder.DefineDynamicModule("MyJumpTableDemo")
      
      Dim myTypeBuilder As TypeBuilder = myModBuilder.DefineType("JumpTableDemo", _
                                 TypeAttributes.Public)
      Dim myMthdBuilder As MethodBuilder = myTypeBuilder.DefineMethod("SwitchMe", _
                        MethodAttributes.Public Or MethodAttributes.Static, _
                        GetType(String), New Type() {GetType(Integer)})
      
      Dim myIL As ILGenerator = myMthdBuilder.GetILGenerator()
      
      Dim defaultCase As Label = myIL.DefineLabel()
      Dim endOfMethod As Label = myIL.DefineLabel()
      
      ' We are initializing our jump table. Note that the labels
      ' will be placed later using the MarkLabel method. 

      Dim jumpTable() As Label = {myIL.DefineLabel(), _
                  myIL.DefineLabel(), _
                  myIL.DefineLabel(), _
                  myIL.DefineLabel(), _
                  myIL.DefineLabel()}
      
      ' arg0, the number we passed, is pushed onto the stack.
      ' In this case, due to the design of the code sample,
      ' the value pushed onto the stack happens to match the
      ' index of the label (in IL terms, the index of the offset
      ' in the jump table). If this is not the case, such as
      ' when switching based on non-integer values, rules for the correspondence
      ' between the possible case values and each index of the offsets
      ' must be established outside of the ILGenerator.Emit calls,
      ' much as a compiler would.

      myIL.Emit(OpCodes.Ldarg_0)
      myIL.Emit(OpCodes.Switch, jumpTable)
      
      ' Branch on default case
      myIL.Emit(OpCodes.Br_S, defaultCase)
      
      ' Case arg0 = 0
      myIL.MarkLabel(jumpTable(0))
      myIL.Emit(OpCodes.Ldstr, "are no bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 1
      myIL.MarkLabel(jumpTable(1))
      myIL.Emit(OpCodes.Ldstr, "is one banana")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 2
      myIL.MarkLabel(jumpTable(2))
      myIL.Emit(OpCodes.Ldstr, "are two bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 3
      myIL.MarkLabel(jumpTable(3))
      myIL.Emit(OpCodes.Ldstr, "are three bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 4
      myIL.MarkLabel(jumpTable(4))
      myIL.Emit(OpCodes.Ldstr, "are four bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Default case
      myIL.MarkLabel(defaultCase)
      myIL.Emit(OpCodes.Ldstr, "are many bananas")
      
      myIL.MarkLabel(endOfMethod)
      myIL.Emit(OpCodes.Ret)
      
      Return myTypeBuilder.CreateType()

   End Function 'BuildMyType
    
   
   Public Shared Sub Main()

      Dim myType As Type = BuildMyType()
      
      Console.Write("Enter an integer between 0 and 5: ")
      Dim theValue As Integer = Convert.ToInt32(Console.ReadLine())
      
      Console.WriteLine("---")
      Dim myInstance As [Object] = Activator.CreateInstance(myType, New Object() {})
      Console.WriteLine("Yes, there {0} today!", myType.InvokeMember("SwitchMe", _
                         BindingFlags.InvokeMethod, Nothing, _
                             myInstance, New Object() {theValue}))

   End Sub

End Class

注解

opcode如果参数需要参数，则调用方必须确保参数长度与声明的参数长度匹配。否则，结果将不可预知。例如，如果 Emit 指令需要 2 字节操作数，并且调用方提供 4 字节操作数，运行时将向指令流发出两个额外的字节。这些额外的字节将是 Nop 说明。

指令值在 . 中 OpCodes定义。

适用于

Emit(OpCode, Label)

将指定的指令放到 Microsoft 中间语言 (MSIL) 流上，并留出在完成修正时加上标签所需的空白。

public:
 virtual void Emit(System::Reflection::Emit::OpCode opcode, System::Reflection::Emit::Label label);

public virtual void Emit (System.Reflection.Emit.OpCode opcode, System.Reflection.Emit.Label label);

abstract member Emit : System.Reflection.Emit.OpCode * System.Reflection.Emit.Label -> unit
override this.Emit : System.Reflection.Emit.OpCode * System.Reflection.Emit.Label -> unit

Public Overridable Sub Emit (opcode As OpCode, label As Label)

参数

opcode: OpCode

要发出到流的 MSIL 指令。

label: Label

从此位置分支到的标签。

示例

下面的代码示例演示了如何使用跳转表创建动态方法。跳转表是使用数组 Label生成的。

using namespace System;
using namespace System::Threading;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
Type^ BuildMyType()
{
   AppDomain^ myDomain = Thread::GetDomain();
   AssemblyName^ myAsmName = gcnew AssemblyName;
   myAsmName->Name = "MyDynamicAssembly";
   AssemblyBuilder^ myAsmBuilder = myDomain->DefineDynamicAssembly( myAsmName, AssemblyBuilderAccess::Run );
   ModuleBuilder^ myModBuilder = myAsmBuilder->DefineDynamicModule( "MyJumpTableDemo" );
   TypeBuilder^ myTypeBuilder = myModBuilder->DefineType( "JumpTableDemo", TypeAttributes::Public );
   array<Type^>^temp0 = {int::typeid};
   MethodBuilder^ myMthdBuilder = myTypeBuilder->DefineMethod( "SwitchMe", static_cast<MethodAttributes>(MethodAttributes::Public | MethodAttributes::Static), String::typeid, temp0 );
   ILGenerator^ myIL = myMthdBuilder->GetILGenerator();
   Label defaultCase = myIL->DefineLabel();
   Label endOfMethod = myIL->DefineLabel();
   
   // We are initializing our jump table. Note that the labels
   // will be placed later using the MarkLabel method.
   array<Label>^jumpTable = gcnew array<Label>(5);
   jumpTable[ 0 ] = myIL->DefineLabel();
   jumpTable[ 1 ] = myIL->DefineLabel();
   jumpTable[ 2 ] = myIL->DefineLabel();
   jumpTable[ 3 ] = myIL->DefineLabel();
   jumpTable[ 4 ] = myIL->DefineLabel();
   
   // arg0, the number we passed, is pushed onto the stack.
   // In this case, due to the design of the code sample,
   // the value pushed onto the stack happens to match the
   // index of the label (in IL terms, the index of the offset
   // in the jump table). If this is not the case, such as
   // when switching based on non-integer values, rules for the correspondence
   // between the possible case values and each index of the offsets
   // must be established outside of the ILGenerator::Emit calls,
   // much as a compiler would.
   myIL->Emit( OpCodes::Ldarg_0 );
   myIL->Emit( OpCodes::Switch, jumpTable );
   
   // Branch on default case
   myIL->Emit( OpCodes::Br_S, defaultCase );
   
   // Case arg0 = 0
   myIL->MarkLabel( jumpTable[ 0 ] );
   myIL->Emit( OpCodes::Ldstr, "are no bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 1
   myIL->MarkLabel( jumpTable[ 1 ] );
   myIL->Emit( OpCodes::Ldstr, "is one banana" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 2
   myIL->MarkLabel( jumpTable[ 2 ] );
   myIL->Emit( OpCodes::Ldstr, "are two bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 3
   myIL->MarkLabel( jumpTable[ 3 ] );
   myIL->Emit( OpCodes::Ldstr, "are three bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Case arg0 = 4
   myIL->MarkLabel( jumpTable[ 4 ] );
   myIL->Emit( OpCodes::Ldstr, "are four bananas" );
   myIL->Emit( OpCodes::Br_S, endOfMethod );
   
   // Default case
   myIL->MarkLabel( defaultCase );
   myIL->Emit( OpCodes::Ldstr, "are many bananas" );
   myIL->MarkLabel( endOfMethod );
   myIL->Emit( OpCodes::Ret );
   return myTypeBuilder->CreateType();
}

int main()
{
   Type^ myType = BuildMyType();
   Console::Write( "Enter an integer between 0 and 5: " );
   int theValue = Convert::ToInt32( Console::ReadLine() );
   Console::WriteLine( "---" );
   Object^ myInstance = Activator::CreateInstance( myType, gcnew array<Object^>(0) );
   array<Object^>^temp1 = {theValue};
   Console::WriteLine( "Yes, there {0} today!", myType->InvokeMember( "SwitchMe", BindingFlags::InvokeMethod, nullptr, myInstance, temp1 ) );
}


using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;

class DynamicJumpTableDemo

{

   public static Type BuildMyType()
   {
    AppDomain myDomain = Thread.GetDomain();
    AssemblyName myAsmName = new AssemblyName();
    myAsmName.Name = "MyDynamicAssembly";

    AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
                        myAsmName,
                        AssemblyBuilderAccess.Run);
    ModuleBuilder myModBuilder = myAsmBuilder.DefineDynamicModule(
                        "MyJumpTableDemo");

    TypeBuilder myTypeBuilder = myModBuilder.DefineType("JumpTableDemo",
                            TypeAttributes.Public);
    MethodBuilder myMthdBuilder = myTypeBuilder.DefineMethod("SwitchMe",
                             MethodAttributes.Public |
                             MethodAttributes.Static,
                                             typeof(string),
                                             new Type[] {typeof(int)});

    ILGenerator myIL = myMthdBuilder.GetILGenerator();

    Label defaultCase = myIL.DefineLabel();	
    Label endOfMethod = myIL.DefineLabel();	

    // We are initializing our jump table. Note that the labels
    // will be placed later using the MarkLabel method.

    Label[] jumpTable = new Label[] { myIL.DefineLabel(),
                      myIL.DefineLabel(),
                      myIL.DefineLabel(),
                      myIL.DefineLabel(),
                      myIL.DefineLabel() };

    // arg0, the number we passed, is pushed onto the stack.
    // In this case, due to the design of the code sample,
    // the value pushed onto the stack happens to match the
    // index of the label (in IL terms, the index of the offset
    // in the jump table). If this is not the case, such as
    // when switching based on non-integer values, rules for the correspondence
    // between the possible case values and each index of the offsets
    // must be established outside of the ILGenerator.Emit calls,
    // much as a compiler would.

    myIL.Emit(OpCodes.Ldarg_0);
    myIL.Emit(OpCodes.Switch, jumpTable);
    
    // Branch on default case
    myIL.Emit(OpCodes.Br_S, defaultCase);

    // Case arg0 = 0
    myIL.MarkLabel(jumpTable[0]);
    myIL.Emit(OpCodes.Ldstr, "are no bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 1
    myIL.MarkLabel(jumpTable[1]);
    myIL.Emit(OpCodes.Ldstr, "is one banana");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 2
    myIL.MarkLabel(jumpTable[2]);
    myIL.Emit(OpCodes.Ldstr, "are two bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 3
    myIL.MarkLabel(jumpTable[3]);
    myIL.Emit(OpCodes.Ldstr, "are three bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Case arg0 = 4
    myIL.MarkLabel(jumpTable[4]);
    myIL.Emit(OpCodes.Ldstr, "are four bananas");
    myIL.Emit(OpCodes.Br_S, endOfMethod);

    // Default case
    myIL.MarkLabel(defaultCase);
    myIL.Emit(OpCodes.Ldstr, "are many bananas");

    myIL.MarkLabel(endOfMethod);
    myIL.Emit(OpCodes.Ret);
    
    return myTypeBuilder.CreateType();
   }

   public static void Main()
   {
    Type myType = BuildMyType();
    
    Console.Write("Enter an integer between 0 and 5: ");
    int theValue = Convert.ToInt32(Console.ReadLine());

    Console.WriteLine("---");
    Object myInstance = Activator.CreateInstance(myType, new object[0]);	
    Console.WriteLine("Yes, there {0} today!", myType.InvokeMember("SwitchMe",
                               BindingFlags.InvokeMethod,
                               null,
                               myInstance,
                               new object[] {theValue}));
   }
}


Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit

 _

Class DynamicJumpTableDemo
   
   Public Shared Function BuildMyType() As Type

      Dim myDomain As AppDomain = Thread.GetDomain()
      Dim myAsmName As New AssemblyName()
      myAsmName.Name = "MyDynamicAssembly"
      
      Dim myAsmBuilder As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, _
                            AssemblyBuilderAccess.Run)
      Dim myModBuilder As ModuleBuilder = myAsmBuilder.DefineDynamicModule("MyJumpTableDemo")
      
      Dim myTypeBuilder As TypeBuilder = myModBuilder.DefineType("JumpTableDemo", _
                                 TypeAttributes.Public)
      Dim myMthdBuilder As MethodBuilder = myTypeBuilder.DefineMethod("SwitchMe", _
                        MethodAttributes.Public Or MethodAttributes.Static, _
                        GetType(String), New Type() {GetType(Integer)})
      
      Dim myIL As ILGenerator = myMthdBuilder.GetILGenerator()
      
      Dim defaultCase As Label = myIL.DefineLabel()
      Dim endOfMethod As Label = myIL.DefineLabel()
      
      ' We are initializing our jump table. Note that the labels
      ' will be placed later using the MarkLabel method. 

      Dim jumpTable() As Label = {myIL.DefineLabel(), _
                  myIL.DefineLabel(), _
                  myIL.DefineLabel(), _
                  myIL.DefineLabel(), _
                  myIL.DefineLabel()}
      
      ' arg0, the number we passed, is pushed onto the stack.
      ' In this case, due to the design of the code sample,
      ' the value pushed onto the stack happens to match the
      ' index of the label (in IL terms, the index of the offset
      ' in the jump table). If this is not the case, such as
      ' when switching based on non-integer values, rules for the correspondence
      ' between the possible case values and each index of the offsets
      ' must be established outside of the ILGenerator.Emit calls,
      ' much as a compiler would.

      myIL.Emit(OpCodes.Ldarg_0)
      myIL.Emit(OpCodes.Switch, jumpTable)
      
      ' Branch on default case
      myIL.Emit(OpCodes.Br_S, defaultCase)
      
      ' Case arg0 = 0
      myIL.MarkLabel(jumpTable(0))
      myIL.Emit(OpCodes.Ldstr, "are no bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 1
      myIL.MarkLabel(jumpTable(1))
      myIL.Emit(OpCodes.Ldstr, "is one banana")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 2
      myIL.MarkLabel(jumpTable(2))
      myIL.Emit(OpCodes.Ldstr, "are two bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 3
      myIL.MarkLabel(jumpTable(3))
      myIL.Emit(OpCodes.Ldstr, "are three bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Case arg0 = 4
      myIL.MarkLabel(jumpTable(4))
      myIL.Emit(OpCodes.Ldstr, "are four bananas")
      myIL.Emit(OpCodes.Br_S, endOfMethod)
      
      ' Default case
      myIL.MarkLabel(defaultCase)
      myIL.Emit(OpCodes.Ldstr, "are many bananas")
      
      myIL.MarkLabel(endOfMethod)
      myIL.Emit(OpCodes.Ret)
      
      Return myTypeBuilder.CreateType()

   End Function 'BuildMyType
    
   
   Public Shared Sub Main()

      Dim myType As Type = BuildMyType()
      
      Console.Write("Enter an integer between 0 and 5: ")
      Dim theValue As Integer = Convert.ToInt32(Console.ReadLine())
      
      Console.WriteLine("---")
      Dim myInstance As [Object] = Activator.CreateInstance(myType, New Object() {})
      Console.WriteLine("Yes, there {0} today!", myType.InvokeMember("SwitchMe", _
                         BindingFlags.InvokeMethod, Nothing, _
                             myInstance, New Object() {theValue}))

   End Sub

End Class

注解

指令值在枚举中 OpCodes 定义。

Labels are created using DefineLabel, and their location within the stream is fixed by using MarkLabel. 如果使用单字节指令，则标签可以表示流中最多 127 字节的跳转。 opcode 必须表示分支指令。由于分支是相对指令， label 因此会在修复过程中替换为分支的正确偏移量。

适用于