比对一下，耗时大约是直接泛型调用耗时的三倍。显然这个方案是一个非常实用的方案。归纳一下，一共需要四步：
using
System;
using
System.Collections.Generic;
using
System.Reflection;
using
System.Reflection.Emit;
using
System.Text;
namespace
GenericMethodTest
{
/// <summary>
/// 接口生成器
/// </summary>
internal static class InterfaceGenerator
{
private static Random _Random = new Random();
private static char GetRandomLetter()
{
int i = (_Random.Next() % 26) + 97;
byte[] b = BitConverter.GetBytes(i);
return BitConverter.ToChar(b, 0);
}
private static string GetRandomString(int n)
{
char[] chars = new char[n];
for (int i = 0; i < n; i++)
{
chars[i] = GetRandomLetter();
}
return new string(chars);
}
private static void LoadArg(ILGenerator gen, int index)
{
switch (index)
{
case 0:
gen.Emit(OpCodes.Ldarg_0);
break;
case 1:
gen.Emit(OpCodes.Ldarg_1);
break;
case 2:
gen.Emit(OpCodes.Ldarg_2);
break;
case 3:
gen.Emit(OpCodes.Ldarg_3);
break;
default:
if (index < 128)
{
gen.Emit(OpCodes.Ldarg_S, index);
}
else
{
gen.Emit(OpCodes.Ldarg, index);
}
break;
}
}
public static T GetInterface<T>(Delegate GM)
{
if (typeof(T).IsInterface)
{
Type delegateType = GM.GetType();
if (delegateType.IsGenericType)
{
if (typeof(MulticastDelegate).IsAssignableFrom(delegateType.GetGenericTypeDefinition()))
{
Type[] genericTypes = delegateType.GetGenericArguments();
if (genericTypes.Length == 1)
{
Type genericType = genericTypes[0];
#if SAVE
string theFilename = "InterfaceGenerator.Attachments.dll";
#endif
AssemblyName aname = new AssemblyName();
aname.Name = string.Format("InterfaceGenerator.Attachments.{0}", GetRandomString(16));
aname.Version = new Version("2.0.0.0");
AssemblyBuilder assembly = AppDomain.CurrentDomain.DefineDynamicAssembly(aname,
#if SAVE
AssemblyBuilderAccess.RunAndSave
#else
AssemblyBuilderAccess.Run
#endif
);
ModuleBuilder module = assembly.DefineDynamicModule(GetRandomString(8)
#if SAVE
, theFilename
#endif
);
TypeBuilder builder = module.DefineType(GetRandomString(16), TypeAttributes.Sealed | TypeAttributes.Class | TypeAttributes.Public);
builder.AddInterfaceImplementation(typeof(T));
// 先定义成员域，用于保存传入的委托。
FieldBuilder field = builder.DefineField(GetRandomString(8), delegateType, FieldAttributes.Private);
// 定义构造器。
ConstructorBuilder ctor = builder.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, new Type[] { delegateType });
ILGenerator ctorGen = ctor.GetILGenerator();
ctorGen.Emit(OpCodes.Ldarg_0);
ctorGen.Emit(OpCodes.Call, typeof(object).GetConstructor(new Type[] { }));
ctorGen.Emit(OpCodes.Ldarg_0);
ctorGen.Emit(OpCodes.Ldarg_1);
ctorGen.Emit(OpCodes.Stfld, field);
ctorGen.Emit(OpCodes.Ret);
// 虽然这么写，但事实上接口只有一个方法。
foreach (MethodInfo bmi in typeof(T).GetMethods())
{
ParameterInfo[] paramInfos = bmi.GetParameters();
Type[] argTypes = new Type[paramInfos.Length];
int i = 0;
foreach (ParameterInfo pi in paramInfos)
{
argTypes[i++] = pi.ParameterType;
}
MethodAttributes attributes = MethodAttributes.HideBySig | MethodAttributes.Virtual | MethodAttributes.ReuseSlot | MethodAttributes.Public;
MethodBuilder method = builder.DefineMethod(bmi.Name, attributes, bmi.ReturnType, argTypes);
builder.DefineMethodOverride(method, bmi);
MethodInfo dmi = delegateType.GetMethod("Invoke");
ILGenerator methodGen = method.GetILGenerator();
bool hasReturn = false;
if (dmi.ReturnType != typeof(void))
{
methodGen.DeclareLocal(dmi.ReturnType);
hasReturn = true;
}
methodGen.Emit(OpCodes.Ldarg_0);
methodGen.Emit(OpCodes.Ldfld, field);
i = 0;
foreach (ParameterInfo pi in dmi.GetParameters())
{
LoadArg(methodGen, i + 1);
if (!pi.ParameterType.IsAssignableFrom(argTypes[i]))
{
if (argTypes[i].IsClass)
{
methodGen.Emit(OpCodes.Castclass, pi.ParameterType);
}
else
{
methodGen.Emit(OpCodes.Unbox, pi.ParameterType);
}
}
i++;
}
methodGen.Emit(OpCodes.Callvirt, dmi);
if (hasReturn)
{
methodGen.Emit(OpCodes.Stloc_0);
methodGen.Emit(OpCodes.Ldloc_0);
}
methodGen.Emit(OpCodes.Ret);
}
Type target = builder.CreateType();
#if SAVE
assembly.Save(theFilename);
#endif
ConstructorInfo ci = target.GetConstructor(new Type[] { delegateType });
return (T) ci.Invoke(new object[] { GM });
}
}
}
}
return default(T);
}
}
}
- 定义泛型委托；
- 定义非泛型接口；
- 实现这个接口；
- 通过泛型委托获取非泛型接口的实现。
其中前两步比较简单，后两部稍嫌麻烦。于是，我们再进一步实现一个通用的接口实现及其输出。
using
System;
using
System.Collections.Generic;
using
System.Reflection;
using
System.Reflection.Emit;
using
System.Text;
namespace
GenericMethodTest
{ /// <summary> /// 接口生成器 /// </summary> internal static class InterfaceGenerator { private static Random _Random = new Random(); private static char GetRandomLetter() { int i = (_Random.Next() % 26) + 97; byte[] b = BitConverter.GetBytes(i); return BitConverter.ToChar(b, 0); } private static string GetRandomString(int n) { char[] chars = new char[n]; for (int i = 0; i < n; i++) { chars[i] = GetRandomLetter(); } return new string(chars); } private static void LoadArg(ILGenerator gen, int index) { switch (index) { case 0: gen.Emit(OpCodes.Ldarg_0); break; case 1: gen.Emit(OpCodes.Ldarg_1); break; case 2: gen.Emit(OpCodes.Ldarg_2); break; case 3: gen.Emit(OpCodes.Ldarg_3); break; default: if (index < 128) { gen.Emit(OpCodes.Ldarg_S, index); } else { gen.Emit(OpCodes.Ldarg, index); } break; } } public static T GetInterface<T>(Delegate GM) { if (typeof(T).IsInterface) { Type delegateType = GM.GetType(); if (delegateType.IsGenericType) { if (typeof(MulticastDelegate).IsAssignableFrom(delegateType.GetGenericTypeDefinition())) { Type[] genericTypes = delegateType.GetGenericArguments(); if (genericTypes.Length == 1) { Type genericType = genericTypes[0];#if SAVE string theFilename = "InterfaceGenerator.Attachments.dll";#endif AssemblyName aname = new AssemblyName(); aname.Name = string.Format("InterfaceGenerator.Attachments.{0}", GetRandomString(16)); aname.Version = new Version("2.0.0.0"); AssemblyBuilder assembly = AppDomain.CurrentDomain.DefineDynamicAssembly(aname,#if SAVE AssemblyBuilderAccess.RunAndSave#else AssemblyBuilderAccess.Run#endif); ModuleBuilder module = assembly.DefineDynamicModule(GetRandomString(8)#if SAVE, theFilename#endif); TypeBuilder builder = module.DefineType(GetRandomString(16), TypeAttributes.Sealed | TypeAttributes.Class | TypeAttributes.Public); builder.AddInterfaceImplementation(typeof(T)); // 先定义成员域，用于保存传入的委托。 FieldBuilder field = builder.DefineField(GetRandomString(8), delegateType, FieldAttributes.Private); // 定义构造器。 ConstructorBuilder ctor = builder.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, new Type[] { delegateType }); ILGenerator ctorGen = ctor.GetILGenerator(); ctorGen.Emit(OpCodes.Ldarg_0); ctorGen.Emit(OpCodes.Call, typeof(object).GetConstructor(new Type[] { })); ctorGen.Emit(OpCodes.Ldarg_0); ctorGen.Emit(OpCodes.Ldarg_1); ctorGen.Emit(OpCodes.Stfld, field); ctorGen.Emit(OpCodes.Ret); // 虽然这么写，但事实上接口只有一个方法。 foreach (MethodInfo bmi in typeof(T).GetMethods()) { ParameterInfo[] paramInfos = bmi.GetParameters(); Type[] argTypes = new Type[paramInfos.Length]; int i = 0; foreach (ParameterInfo pi in paramInfos) { argTypes[i++] = pi.ParameterType; } MethodAttributes attributes = MethodAttributes.HideBySig | MethodAttributes.Virtual | MethodAttributes.ReuseSlot | MethodAttributes.Public; MethodBuilder method = builder.DefineMethod(bmi.Name, attributes, bmi.ReturnType, argTypes); builder.DefineMethodOverride(method, bmi); MethodInfo dmi = delegateType.GetMethod("Invoke"); ILGenerator methodGen = method.GetILGenerator(); bool hasReturn = false; if (dmi.ReturnType != typeof(void)) { methodGen.DeclareLocal(dmi.ReturnType); hasReturn = true; } methodGen.Emit(OpCodes.Ldarg_0); methodGen.Emit(OpCodes.Ldfld, field); i = 0; foreach (ParameterInfo pi in dmi.GetParameters()) { LoadArg(methodGen, i + 1); if (!pi.ParameterType.IsAssignableFrom(argTypes[i])) { if (argTypes[i].IsClass) { methodGen.Emit(OpCodes.Castclass, pi.ParameterType); } else { methodGen.Emit(OpCodes.Unbox, pi.ParameterType); } } i++; } methodGen.Emit(OpCodes.Callvirt, dmi); if (hasReturn) { methodGen.Emit(OpCodes.Stloc_0); methodGen.Emit(OpCodes.Ldloc_0); } methodGen.Emit(OpCodes.Ret); } Type target = builder.CreateType();#if SAVE assembly.Save(theFilename);#endif ConstructorInfo ci = target.GetConstructor(new Type[] { delegateType }); return (T) ci.Invoke(new object[] { GM }); } } } } return default(T); } }}
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本文转自 obarton 51CTO博客，原文链接:http://blog.51cto.com/kanas/285944
