如何在运行时加载类库 DLL 并使用 VB.NET 运行类函数? [英] How do I load a Class Library DLL at runtime and run a class function using VB.NET?

问题描述

假设我在名为 SomeClass 的类库项目中有一个这样的类-

Say I've a class like this inside a class library project called SomeClass-

Public Class SomeClass
  Public Function DoIt() as String
    Return "Do What?"
  End Function
End Class

我得到一个 SomeClass.dll，我想在运行时从另一个 Windows 窗体应用程序加载它，然后让它调用 DoIt() 函数并显示它的值在消息框或其他东西中.我该怎么做?

I get a SomeClass.dll which I want to load at runtime from another Windows Forms Application, and then have it call the DoIt() function and show it's value in a messagebox or something. How do I do that?

推荐答案

我建议让 DoIt 共享，因为它不需要类状态:

I suggest to make DoIt shared, since it does not require class state:

Public Class SomeClass
    Public Shared Function DoIt() as String
        Return "Do What?"
    End Function
End Class

然后调用它很容易:

' Loads SomeClass.dll
Dim asm = Assembly.Load("SomeClass")  

' Replace the first SomeClass with the base namespace of your SomeClass assembly
Dim type = asm.GetType("SomeClass.SomeClass")

Dim returnValue = DirectCast(type.InvokeMember("DoIt", _
                                               BindingFlags.InvokeMethod | BindingFlags.Static, _
                                               Nothing, Nothing, {}),
                             String)

如果您无法共享该方法，您可以使用 Activator.CreateInstance 并将其作为参数传递给 Type.InvokeMember.

If you cannot make the method shared, you can create an instance of your class with Activator.CreateInstance and pass it as a parameter to Type.InvokeMember.

_{我所有的代码示例都假设 Option Strict On 和 Option Infer On.}

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