相同类型的两个对象的 InvalidCastException

问题描述

我有一个我无法自己处理的奇怪问题.我的 mvp 项目模型中设计为单例的类导致 InvalidCastException.

I have this weird problem that I cannot handle myself. A class in the model of my mvp-project designed as singleton causes an InvalidCastException.

错误的根源在此代码行中，其中将反序列化的对象分配给类的实例变量:engineObject = (ENGINE)xSerializer.Deserialize(str);.每当我尝试将我的用户控件之一添加到表单或不同的 UC 时，都会发生这种情况.我所有的 UC 都有一个特殊的 Presenter，它可以访问上面提到的单例类的实例变量.

The source of error is found in this code line where the deserialised object is assigned to the instance variable of the class: engineObject = (ENGINE)xSerializer.Deserialize(str);. It occurs whenever I try to add one of my UserControls to a Form or to a different UC. All of my UCs have a special presenter that accesses the above mentioned instance variable of the singleton class.

这是我尝试在某处添加 UC 时得到的结果:

This is what I get when trying to add a UC somewhere:

'System.TypeInitializationException: The type initializer for 'MVP.Model.EngineData' threw an exception. ----> 

System.InvalidCastException: [A]Engine cannot be cast to [B]Engine. Type A originates from 'MVP.Model, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' in the context 'LoadNeither' 
   at location '[...]AppDataRoamingMicrosoftVisualStudio9.0ProjectAssembliesuankw1hh01MVP.Model.dll'. 
Type B originates from 'MVP.Model, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' in the context 'LoadNeither' 
   at location '[...]AppDataRoamingMicrosoftVisualStudio9.0ProjectAssembliesu_hge2de01MVP.Model.dll'
...

所以我不知何故有两个程序集，它们不是从我的项目文件夹中访问的，而是从 VS 临时文件夹中访问的?我搜索了很多，只发现了这个:IronPython 例外:[A]Person 不能转换为 [B]Person.提供了一个解决方案，但它涉及 IronPhyton，我不知道在我的项目中在哪里使用它.

So I somehow have two assemblies and they are not accessed from my project folder, but from a VS temp folder? I googled a lot and only found this: IronPython Exception: [A]Person cannot be cast to [B]Person. There is a solution offered, but it concerns IronPhyton and I don't know where to use it within my project.

推荐答案

类型是每个程序集的；如果您将相同"程序集加载了两次，则程序集的每个副本"中的类型都不会被视为相同类型.

Types are per-assembly; if you have "the same" assembly loaded twice, then types in each "copy" of the assembly are not considered to be the same type.

当两个程序集位于 Load 和 LoadFrom 上下文中时，通常会出现这些问题.见

These issues normally crop up when the two assemblies are in the Load and LoadFrom contexts. See

LoadFile 和 LoadFrom 与 .NET 程序集的区别?

以及 suzcook 博客的链接，了解有关该问题的详细信息.

and the link to suzcook's blog for details on that issue.

另外，考虑使用融合日志查看器来帮助诊断问题.

Also, consider using the fusion log viewer to help diagnose the problem.

http://msdn.microsoft.com/en-us/library/e74a18c4%28VS.71%29.aspx

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