我认为你能做的***的/最简单的事情是让GUI仅在C＃中，在Windows客户端，你可以使用Windows窗体或WPF，在基于Web的，你可以使用ASP.NET的WebForms或ASP.NET MVC。

I think the best/easiest thing you could do is make the GUI only in C#, in windows clients you could use Windows Forms or WPF, in web based you can use ASP.NET WebForms or ASP.NET MVC.

在所有这些情况下，除了MVC（剃刀），你必须设计和定制Visual Studio中的GUI真的很不错的工具。

in all these cases except MVC (Razor) you have really good tools for designing and customizing the GUI within Visual Studio.

您C ++代码可以被包装在一个类库或像你说通过某种IPC的访问是否具有作为应用程序的Java运行时，相同的，但如果你是100％免费写，重新写的东西，你也能想象到端口Java代码到C ++，这可能是容易的，很难或不可能取决于Java代码做什么。

Your C++ code can be wrapped in a class library or as you say accessed via some kind of IPC if it has to run as application, same for Java but if you are 100% free to write and re-write things you could also imagine to port the Java code to C++, this could be easy, difficult or impossible depending on what the java code does.

在最后的手段，如果C ++和Java应用程序必须保持分离，必须在相同或另一台计算机上后台运行，您仍想从C＃GUI消耗他们的服务或方法，如你所说，IPC大概的样子，不知道你可以在Windows中使用Java和IPC做什么，想必Java可以暴露或使用XML Web服务。

at last resort if both C++ and Java applications must stay separated and must run in background on same or another machine and you still want to consume their services or methods from your C# GUI, as you mentioned, IPC is probably the way, not sure what you can do in Windows with Java and IPC, surely java can expose or consume XML web services.