当前位置：文江博客话题详情

通过反射动态继承内部类

发布于 2024-12-21 05:12:57 字数 62 浏览 1 评论 0原文

有没有办法使用 .NET Framework 4.0 从动态生成的运行时类（例如通过反射）中的内部抽象类继承？

原文

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

谁许谁一生繁华 2024-12-28 05:12:57

面对不应该发生的事情，出于普遍的反常意识，我尝试了一下，看看我能在尝试创建一个继承自 System.CurrentSystemTimeZone 的类时走多远。（mscorlib 中的内部类）。它可以让您创建一个 TypeBuilder，但是当您调用 CreateType 时，它会抛出一个 TypeLoadException 并显示消息“访问被拒绝：'System .当前系统时区'。”

稍微摆弄一下，我得出的结论是，您可以动态创建一个程序集，该程序集具有将其标识为定义内部类型的程序集的友元程序集的强名称。但是，在这种情况下，您无论如何都可以编写 class Foo : CurrentSystemTimeZone ，而不会留下任何诡计。

无论如何，就抛出的行而言，代码如下，以防万一有人有心情尝试一些更反常的想法变体，并想要一个起点：

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

namespace ReflectPerversely
{
    class SuicidallyWrong
    {
        private static ModuleBuilder mb;
        public static Assembly ResolveEvent(Object sender, ResolveEventArgs args)
        {
            return mb.Assembly;
        }
        public static void Main(string[] args)
        {
            Assembly sys = Assembly.GetAssembly(typeof(string));
            Type ic = sys.GetType("System.CurrentSystemTimeZone",true);
            AssemblyName an = new AssemblyName();
            an.Name = "CheatingInternal";
            AssemblyBuilder ab = Thread.GetDomain().DefineDynamicAssembly(an, AssemblyBuilderAccess.RunAndSave);
            mb = ab.DefineDynamicModule("Mod", "CheatingInternal.dll");
            AppDomain currentDom = Thread.GetDomain();
            currentDom.TypeResolve += ResolveEvent;

            TypeBuilder tb = mb.DefineType("Cheat", TypeAttributes.NotPublic | TypeAttributes.Class, ic);

            Type cheatType = tb.CreateType();
        }
    }
}

Out of a general sense of perversity in the face of things that shouldn't be possible, I gave it a go at seeing how far I would get at trying to create a class that inherited from System.CurrentSystemTimeZone (an internal class in mscorlib). It let's you get as far as creating a TypeBuilder but when you call CreateType it throws a TypeLoadException with the message "Access is denied: 'System.CurrentSystemTimeZone'."

A bit more fiddling as led me to conclude that you could create an assembly dynamically which had the strong name that identified it as a friend assembly of the assembly in which the internal type is defined. But then, in that case you could just code class Foo : CurrentSystemTimeZone anyway, with no trickery being left.

Anyway, the code as far as the line which throws is below, just in case anyone is in the mood for trying some even more perverse variant on the idea, and wants a starting point:

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

namespace ReflectPerversely
{
    class SuicidallyWrong
    {
        private static ModuleBuilder mb;
        public static Assembly ResolveEvent(Object sender, ResolveEventArgs args)
        {
            return mb.Assembly;
        }
        public static void Main(string[] args)
        {
            Assembly sys = Assembly.GetAssembly(typeof(string));
            Type ic = sys.GetType("System.CurrentSystemTimeZone",true);
            AssemblyName an = new AssemblyName();
            an.Name = "CheatingInternal";
            AssemblyBuilder ab = Thread.GetDomain().DefineDynamicAssembly(an, AssemblyBuilderAccess.RunAndSave);
            mb = ab.DefineDynamicModule("Mod", "CheatingInternal.dll");
            AppDomain currentDom = Thread.GetDomain();
            currentDom.TypeResolve += ResolveEvent;

            TypeBuilder tb = mb.DefineType("Cheat", TypeAttributes.NotPublic | TypeAttributes.Class, ic);

            Type cheatType = tb.CreateType();
        }
    }
}

回复收藏 0 原文