在将对象的名称作为String传递时,如何动态创建对象的实例？(VB.NET)

Question

我有一个包含许多类的类库.我想动态创建这些类之一的实例,设置其属性,并调用方法.

例:

Public Interface IExample
    Sub DoSomething()
End Interface

Public Class ExampleClass
    Implements IExample

    Dim _calculatedValue as Integer

    Public Property calculatedValue() as Integer
        Get
            return _calculatedValue
        End Get
        Set(ByVal value As Integer)
            _calculatedValue= value
        End Set
    End Property        

    Public Sub DoSomething() Implements IExample.DoSomething
        _calculatedValue += 5
    End Sub
End Class

Public Class Example2
    Implements IExample

    Dim _calculatedValue as Integer

    Public Property calculatedValue() as Integer
        Get
            return _calculatedValue
        End Get
        Set(ByVal value As Integer)
            _calculatedValue = value
        End Set
    End Property        

    Public Sub DoSomething() Implements IExample.DoSomething
        _calculatedValue += 7
    End Sub
End Class

所以,我想创建如下代码.

Private Function DoStuff() as Integer
    dim resultOfSomeProcess as String = "Example2"

    dim instanceOfExampleObject as new !!!resultOfSomeProcess!!! <-- this is it

    instanceOfExampleObject.calculatedValue = 6
    instanceOfExampleObject.DoSomething()

    return instanceOfExampleObject.calculatedValue
End Function

Example1和Example2可能有不同的属性,我需要设置...

这可行吗？

Answer 1

你可以用Activator.CreateInstance它.最简单的方法(IMO)是首先创建一个Type对象并将其传递给Activator.CreateInstance:

Dim theType As Type = Type.GetType(theTypename)
If theType IsNot Nothing Then
    Dim instance As IExample = DirectCast(Activator.CreateInstance(theType), IExample)
    ''# use instance
End If

请注意,包含类型名称的字符串必须包含完整的类型名称,包括命名空间.

如果你需要访问类型上更专业的成员,你仍然需要转换它们(除非VB.NET已经包含类似于dynamicC#的东西,我不知道).