遍历类属性

Question

我有一个名为 ticket 的 VB.NET 类，它有几个“字段”类型的公共属性。我想有一种方法可以遍历所有这些属性（每个属性都有一个）并在每个属性上执行特定任务。我认为也许最好的方法是创建一个列表（字段）并用该类的“字段”属性填充列表。我不知道如何动态地将属性添加到列表中，这样如果我将来添加属性，我就不必手动将它们输入到列表中。关于我如何做到这一点的任何想法？我尝试搜索并找到了一些使用反射的示例，但我只能弄清楚如何获取属性的名称而不是属性本身。

这是一个类的例子：

Public Class ticket
    Public Property location As New field
    Public Property user As New field
    Public Property callType As New field
    Public Property dateOfCall As New field
    Public Property tech As New field
    Public Property description As New field

    Public Property myFields As New List(Of field)

'What if field had a property of value and I wanted to increment all of the fields    in this class by one

Public Sub plusOne()
    For Each x As field In myFields()
        x.value += 1
    Next
End Sub

End Class

Answer 1

您想使用Reflection，这意味着检查程序集中的类型。您可以通过 System.Reflection 命名空间来执行此操作。

有关 VB.Net 中反射的示例，请参阅 msdn 杂志上的以下文章： http://msdn.microsoft.com/en-us/magazine/cc163750.aspx

该文章中迭代类型成员的示例如下：

Dim t As Type = GetType(AcmeCorp.BusinessLogic.Customer)
For Each member As MemberInfo In t.GetMembers
  Console.WriteLine(member.Name)
Next

Answer 2

再次作为之前的答案 - 您将使用反射。以List(Of T) 上的Add 为例，我会这样做。

Public Class Test
  Public Property SomeList As List(Of String)
End Class

然后使用下面的代码在List(Of String)上调用add

Dim pi As PropertyInfo = GetType(Test).GetProperty("SomeList")
Dim mi As MethodInfo = GetType(List(Of String)).GetMethod("Add")
Dim t As New Test()
t.SomeList = New List(Of String)
mi.Invoke(pi.GetValue(t, Nothing), New Object() {"Added through reflection"})

Answer 3

正如前面的答案所说，您需要使用 System.Reflection 来获取类的属性。然后检查属性是你想要的类型。

希望这能满足您的需求。如果您运行代码，您将看到它只采用指定类型的属性。如果您想拥有所有属性，请删除 for each 循环上的 where 语句。

Imports System.Reflection

Module Module1

Sub Main()

    ' Create a list to hold your properties
    Dim myList As New List(Of MyProperty)

    ' check each property for its type using the where statement below. Change integer to "Field" in your case
    For Each el In GetType(Test).GetProperties.Where(Function(p) p.PropertyType = GetType(Integer))
        ' add each matching property to the list
        myList.Add(New MyProperty With {.Name = el.Name, .GetMethod = el.GetGetMethod(), .SetMethod = el.GetSetMethod()})
        Console.WriteLine(el.Name & " has been added to myList")
    Next

    Console.Read()
End Sub

Public Class MyProperty
    Public Property Name As String
    Public Property GetMethod As MethodInfo
    Public Property SetMethod As MethodInfo
End Class

Public Class Test
    Private var1 As String
    Private var2 As String
    Private var3 As String
    Private var4 As String

    Public Property myInt1 As Integer
    Public Property myInt2 As Integer
    Public Property myInt3 As Integer
    Public Property myInt4 As Integer
End Class
End Module

希望有帮助