public interface IProxy{void GetProxyInstance();}public static class Util{public static void Before(string message){Console.WriteLine( $"dynamic message: {message}" );}}public class TypeCreator{private readonly Type _targetType;public TypeCreator(Type targetType){this._targetType = targetType;}public Type Build(){var currentAppDomain = AppDomain.CurrentDomain;var assemblyName = new AssemblyName {Name = "_Aop_Assembly_" + this._targetType.Name};var assemblyBuilder = currentAppDomain.DefineDynamicAssembly( assemblyName, AssemblyBuilderAccess.Run );var moduleBuilder = assemblyBuilder.DefineDynamicModule( "_Aop_Module_" + this._targetType.Name );var implTypeName = "_Impl_" + this._targetType.Name;var implTypeAttribute = TypeAttributes.Class | TypeAttributes.Public;Type implTypeParent;Type[] implTypeInterfaces;if( this._targetType.IsInterface ){implTypeParent = null;implTypeInterfaces = new[] {this._targetType};}else{implTypeParent = this._targetType;implTypeInterfaces = new Type[0];}var typeBuilder = moduleBuilder.DefineType( implTypeName, implTypeAttribute, implTypeParent, implTypeInterfaces );var implTargetMethods = this._targetType.GetMethods();foreach( var implTargetMethod in implTargetMethods ){if( implTargetMethod.IsVirtual ){var parameters = implTargetMethod.GetParameters();var parameterTypes = new Type[parameters.Length];for( var i = 0; i < parameters.Length; i++ ){parameterTypes[i] = parameters[i].ParameterType;}var methodBuilder = typeBuilder.DefineMethod( implTargetMethod.Name, MethodAttributes.Public | MethodAttributes.Virtual, implTargetMethod.ReturnType, parameterTypes );var ilGen = methodBuilder.GetILGenerator();ilGen.Emit( OpCodes.Ldstr, "Before Execute " + this._targetType.Name + ";" );ilGen.Emit( OpCodes.Call, typeof( Util ).GetMethod( "Before", new Type[] {typeof( string )} ) );ilGen.Emit( OpCodes.Ret );}}return typeBuilder.CreateType();}}// 调用示例：var tc = new TypeCreator( typeof( IProxy ) );var dynamicType = tc.Build();var proxy = (IProxy) Activator.CreateInstance( dynamicType );proxy.GetProxyInstance();

  public class ViewModelBase{protected void RaisePropertyChanged( string propertyName ){Console.WriteLine( $"PropertyName: {propertyName}" );}}[AttributeUsage(AttributeTargets.Property)]public class RaisePropertyChangedAttribute : Attribute{}public class SampleViewModel : ViewModelBase{[RaisePropertyChanged]public virtual string SomeProperty { get; set; }}public static class ReflectionEmitViewModelFactory{public static T CreateInstance<T>()where T : ViewModelBase{Type vmType = typeof(T);VerifyViewModelType(vmType);// Create everything required to get a module builderAssemblyName assemblyName = new AssemblyName("SmartViewModelDynamicAssembly");AppDomain domain = AppDomain.CurrentDomain;AssemblyBuilder assemblyBuilder = domain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);//AssemblyBuilderAccess.RunAndSave);ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyName.Name);string dynamicTypeName = Assembly.CreateQualifiedName(vmType.AssemblyQualifiedName, "Smart" + vmType.Name);TypeBuilder typeBuilder = moduleBuilder.DefineType(dynamicTypeName,TypeAttributes.Public | TypeAttributes.Class, vmType);MethodInfo raisePropertyChangedMethod = typeof(ViewModelBase).GetMethod("RaisePropertyChanged",BindingFlags.NonPublic | BindingFlags.Instance, null, new Type[] { typeof(string) }, null);foreach( PropertyInfo propertyInfo in FindNotifyPropertyChangCandidates<T>() )UpdateProperty(propertyInfo, typeBuilder, raisePropertyChangedMethod);Type dynamicType = typeBuilder.CreateType();return (T)Activator.CreateInstance(dynamicType);}private static void VerifyViewModelType( Type vmType ){if( vmType.IsSealed )throw new InvalidOperationException("The specified view model type is not allowed to be sealed.");}private static IEnumerable<PropertyInfo> FindNotifyPropertyChangCandidates<T>(){return from p in typeof(T).GetProperties()where p.GetSetMethod() != null && p.GetSetMethod().IsVirtual &&p.GetCustomAttributes(typeof(RaisePropertyChangedAttribute), false).Length > 0select p;}private static void UpdateProperty( PropertyInfo propertyInfo, TypeBuilder typeBuilder,MethodInfo raisePropertyChangedMethod ){// Update the setter of the classPropertyBuilder propertyBuilder = typeBuilder.DefineProperty(propertyInfo.Name,PropertyAttributes.None, propertyInfo.PropertyType, null);// Create set methodMethodBuilder builder = typeBuilder.DefineMethod("set_" + propertyInfo.Name,MethodAttributes.Public | MethodAttributes.Virtual, null, new Type[] { propertyInfo.PropertyType });builder.DefineParameter(1, ParameterAttributes.None, "value");ILGenerator generator = builder.GetILGenerator();// Add IL code for set method
          generator.Emit(OpCodes.Nop);generator.Emit(OpCodes.Ldarg_0);generator.Emit(OpCodes.Ldarg_1);generator.Emit(OpCodes.Call, propertyInfo.GetSetMethod());// Call property changed for object
          generator.Emit(OpCodes.Nop);generator.Emit(OpCodes.Ldarg_0);generator.Emit(OpCodes.Ldstr, propertyInfo.Name);generator.Emit(OpCodes.Callvirt, raisePropertyChangedMethod);generator.Emit(OpCodes.Nop);generator.Emit(OpCodes.Ret);propertyBuilder.SetSetMethod(builder);}}//调用示例：SampleViewModel viewModel = ReflectionEmitViewModelFactory.CreateInstance<SampleViewModel>();viewModel.SomeProperty = "10";