Question

我参考下面的链接：

http://rogeralsing.com/2008/02/28/linq-expressions-creating-objects/

是否可以通过提供类名来增强它来创建对象？基本上通过使用Lambda Expression

来实现Activator.CreateInstance可以在下面执行的操作

Dim typeName As String = "Testing.ClassNameth, Testing"
Dim typ As Type = Type.GetType(typeName)
Dim testObj = Activator.CreateInstance(typ)
Dim methodInfo As MethodInfo = testObj.GetType().GetMethod("TestPrintObject")

我这样做的目的是因为Activator.CreateInstance的性能非常慢。

谢谢！

Answer 1

确定。经过少量研究，下面是答案：将以下功能添加到您的任何相关课程中：

Public Function GetActivator(Of T)(type As Type) As ObjectActivator(Of T)
    'make a NewExpression that calls the
    'ctor with the args we just created
    Dim newExp As NewExpression = Expression.[New](type)

    'create a lambda with the New
    'Expression as body
    Dim lambda As LambdaExpression = Expression.Lambda(GetType(ObjectActivator(Of T)), newExp)

    'compile it
    Dim compiled As ObjectActivator(Of T) = DirectCast(lambda.Compile(), ObjectActivator(Of T))
    Return compiled
End Function

 Public Delegate Function ObjectActivator(Of T)() As T

然后我们可以将上面的函数称为：

Dim typeName As String = "Testing.ClassNameth, Testing"
Dim typ As Type = Type.GetType(typeName)
Dim testObj As Object = YourHelperClassInstance.GetActivator(Of Object)(typ).Invoke()

希望这篇文章能帮助将来的某个人。

谢谢！

使用基于类名的Lambda表达式创建对象

1 个答案: