在运行时生成类

Question

我目前正在处理一个包含数据的文件。

数据可以在不同的类中，并且这些类在同一个文件中定义。

我目前能够将类输出到 json，并且我能够将数据作为 json 转换为这些类

问题是我希望能够动态创建一个类来处理移动中的数据，而不是简单地将其打印为文件。

类示例：

Class id:4 - name Item

public Int id
public I18N nameId
public Int typeId
public I18N descriptionId
public Int iconId
public Int level
public Int realWeight
public Bool cursed
public Int useAnimationId
public Bool usable
public Bool targetable
public Bool exchangeable
public Double price
public Bool twoHanded
public Bool etheral
public Int itemSetId
public String criteria
public String criteriaTarget
public Bool hideEffects
public Bool enhanceable
public Bool nonUsableOnAnother
public Int appearanceId
public Bool secretRecipe
public Int recipeSlots
public vector<UInt> recipeIds
public vector<UInt> dropMonsterIds
public Bool bonusIsSecret
public vector<EffectInstance> possibleEffects
public vector<UInt> favoriteSubAreas
public Int favoriteSubAreasBonus
public Int craftXpRatio
public Bool needUseConfirm
public Bool isDestructible
public vector<vector<Double>> nuggetsBySubarea
public vector<UInt> containerIds
public vector<vector<Int>> resourcesBySubarea

类型是从带有枚举的 Uint 定义的：

  Public Enum GameDataTypeEnum
        Int = -1
        Bool = -2
        [String] = -3
        [Double] = -4
        I18N = -5
        UInt = -6
        Vector = -99
    End Enum

为了解决这个问题，我尝试将枚举类型转换为 vb.net 类型，例如：

Dim myType1 As Type = Type.GetType("System.Int32")

然后我尝试像这样使用 Activator.CreateInstance：

Dim Type1 As Type = Type.GetType("System.String")
Dim Type2 As Type = Type.GetType("System.Int32")
Dim dictType As Type = GetType(Dictionary(Of , )).MakeGenericType(Type1, Type2)
Dim dict = Activator.CreateInstance(dictType)
dict.add("test", 32)
Console.WriteLine(dict.Item("test"))

这很好用，但是回顾这个解决方案它是不可行的，因为类有不同的类型。无论如何，您会看到从文件中创建类并动态生成它们吗？

最坏的情况是我可以手动生成所有类，但是有很多类并且需要很多时间

---

Vincent 的解决方案可以很好地解决一个小问题。

当我读取文件时，一个字段可能包含另一个字段，这些字段称为向量，可以表示为：List Of (Contained Value)

现在我只需这样做：

For Each field As GameDataField In classDefinition.Value.Fields
    Console.WriteLine(field.fieldName & " --- " & testcast(getFieldTypeString(field)))
    Console.WriteLine(field.fieldName & " --- " & field.fieldType)
    ClassProperties.Add(field.fieldName, Type.GetType(testcast(getFieldTypeString(field))))
Next

我的testcast() 函数只是返回一个字符串，将枚举转换为正确的格式，例如Int 到System.Int32

对于我的 getFieldTypeString 我有：

If isPrimitiveFieldType(field) Then
    Return getPrimitiveFieldTypeString(field)
Else
    Return getCompositeFieldTypeString(field)
End If

原始给出：

Private Function getPrimitiveFieldTypeString(field As GameDataField) As String
    Return If(field.fieldType > 0, classDefinitions(CInt(field.fieldType)).Name, field.fieldType.ToString())
End Function

复合给出：

Private Function getCompositeFieldTypeString(field As GameDataField) As String
    Dim compositeFieldTypeBuilder As New StringBuilder()
    compositeFieldTypeBuilder.Append("System.Collections.Generic.List(Of ")
    If getFieldTypeString(field.innerField) = "UInt" Then
        compositeFieldTypeBuilder.Append("UInt32)")
    ElseIf getFieldTypeString(field.innerField) = "Int" Then
        compositeFieldTypeBuilder.Append("Integer)")
    Else
        compositeFieldTypeBuilder.Append(getFieldTypeString(field.innerField)).Append(")")
    End If
    Return compositeFieldTypeBuilder.ToString()
End Function

如何向 ClassProperties 添加一个属性来表示：

List of a List of a Type

Answer 1

正如 cmets 中已经提到的，this answer（连同this fix）将帮助您动态创建类。

要获取/设置这些类的属性，我们可以创建两个使用反射的扩展方法，以便按名称访问属性 getter/setter：

Imports System.Runtime.CompilerServices

Public Module Extensions

    ''' <summary>
    ''' Uses Reflection to get the value of the specified property.
    ''' </summary>
    ''' <param name="Instance">The object instance which's property to access.</param>
    ''' <param name="PropertyName">The name of the property which's value to get.</param>
    ''' <param name="Arguments">Arguments to pass along to the property method (if any).</param>
    ''' <remarks></remarks>
    <Extension()> _
    Public Function GetProperty(ByVal Instance As Object, ByVal PropertyName As String, Optional ByVal Arguments As Object() = Nothing) As Object
        Return Instance.GetType().GetProperty(PropertyName).GetValue(Instance, Arguments)
    End Function

    ''' <summary>
    ''' Uses Reflection to set the value of the specified property.
    ''' </summary>
    ''' <param name="Instance">The object instance which's property to access.</param>
    ''' <param name="PropertyName">The name of the property which's value to set.</param>
    ''' <param name="Value">The new value to give the property.</param>
    ''' <param name="Arguments">Arguments to pass along to the property method (if any).</param>
    ''' <remarks></remarks>
    <Extension()> _
    Public Sub SetProperty(ByVal Instance As Object, ByVal PropertyName As String, ByVal Value As Object, Optional ByVal Arguments As Object() = Nothing)
        Instance.GetType().GetProperty(PropertyName).SetValue(Instance, Value, Arguments)
    End Sub
End Module

注意：

由于您似乎无法在 System.Object 上使用扩展方法，因此您只需正常调用它们即可：

Extensions.SetProperty(MyObject, "MyProperty", MyValue)

但是，对于任何不是直接 System.Object 的东西，您可以像往常一样使用这些扩展方法：

Button1.SetProperty("Text", "Click me!")

现在你可以像这样使用它们了：

'Just a quick mockup of properties.
Dim ClassProperties As New Dictionary(Of String, Type) From {
    {"name", Type.GetType("System.String")},
    {"id", Type.GetType("System.Int32")},
    {"hasCar", Type.GetType("System.Boolean")}
}

'Create the class type.
Dim CustomClass As Type = CreateClass("Person", ClassProperties)

'Create an instance of the class.
Dim MyPerson As Object = Activator.CreateInstance(CustomClass)

'Modify its properties.
Extensions.SetProperty(MyPerson, "name", "John Doe")
Extensions.SetProperty(MyPerson, "id", 12345)
Extensions.SetProperty(MyPerson, "hasCar", True)

MessageBox.Show( _
        String.Join(Environment.NewLine, {Extensions.GetProperty(MyPerson, "name"), _
                                          Extensions.GetProperty(MyPerson, "id"), _
                                          Extensions.GetProperty(MyPerson, "hasCar")}), _
        "", MessageBoxButtons.OK, MessageBoxIcon.Information)

利润！