在执行期间修改C#类方法

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

public class MyClass
{
    public void MyMethod()
    {
        Console.WriteLine("Original method");
    }
}

public class Program
{
    public static void Main()
    {
        MyClass obj = new MyClass();
        obj.MyMethod();

        Type type = typeof(MyClass);
        MethodInfo method = type.GetMethod("MyMethod");

        DynamicMethod dynMethod = new DynamicMethod("MyMethod", null, new Type[] { });
        ILGenerator il = dynMethod.GetILGenerator();

        il.Emit(OpCodes.Ldstr, "Modified method");
        il.Emit(OpCodes.Call, typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }));
        il.Emit(OpCodes.Ret);

        method.SetMethodBody(dynMethod);

        obj.MyMethod();
    }
}