我正在使用工厂从实现相同通用接口的多个服务中进行选择。我有这样写的工厂:
Public Class JurisdictionServiceFactory
Private JurisdictionTypeMapper As Dictionary(Of String, Object)
Sub New()
JurisdictionTypeMapper = New Dictionary(Of String, Object)
JurisdictionTypeMapper.Add("CountryJurisdiction", ProjectGlobals.UnityContainer.Resolve(Of IJurisdictionService(Of CountryJurisdiction)))
JurisdictionTypeMapper.Add("StateJurisdiction", ProjectGlobals.UnityContainer.Resolve(Of IJurisdictionService(Of StateJurisdiction)))
JurisdictionTypeMapper.Add("CountyJurisdiction", ProjectGlobals.UnityContainer.Resolve(Of IJurisdictionService(Of CountyJurisdiction)))
JurisdictionTypeMapper.Add("CityJurisdiction", ProjectGlobals.UnityContainer.Resolve(Of IJurisdictionService(Of CityJurisdiction)))
JurisdictionTypeMapper.Add("OtherJurisdiction", ProjectGlobals.UnityContainer.Resolve(Of IJurisdictionService(Of OtherJurisdiction)))
End Sub
Public Function getJurisdictionService(type As String) As Object
Return JurisdictionTypeMapper(type)
End Function
End Class
我想用允许编译器知道对象上存在什么方法的东西来代替'Object'作为值类型。例如,我希望能够使用自动完成功能。我已经尝试过这样做:Private JurisdictionTypeMapper As Dictionary(Of String, IJurisdictionService(Of ))
,但是我只收到一条消息:“预期类型”。
这是IJurisdictionService:
Public Interface IJurisdictionService(Of t)
Inherits IDisposable
Function GetJurisdictionsByCompany(companyId As Integer) As List(Of t)
Sub AddJurisdiction(jurisdiction As t)
End Interface
这是示例实现:
Public Class CountryJurisdictionService
Implements IJurisdictionService(Of CountryJurisdiction)
Private jurisdictionRepository As IRepository(Of CountryJurisdiction)
Public Sub New(jurisdictionRepository As IRepository(Of CountryJurisdiction))
Me.jurisdictionRepository = jurisdictionRepository
End Sub
Public Sub AddJurisdiction(jurisdiction As CountryJurisdiction) Implements IJurisdictionService(Of CountryJurisdiction).AddJurisdiction
jurisdictionRepository.Add(jurisdiction)
jurisdictionRepository.Commit()
End Sub
Public Function GetJurisdictionsByCompany(companyId As Integer) As List(Of CountryJurisdiction) Implements IJurisdictionService(Of CountryJurisdiction).GetJurisdictionsByCompany
Return jurisdictionRepository.GetMany(Function(j) j.CompanyID = companyId, False)
End Function
End Class
编辑:这是将在以下环境中使用工厂的上下文:
Public Sub AddJurisdiction(jurisdiction)
Using jurisdictionService = jurisdictionServiceFactory.getJurisdictionService(TypeName(jurisdiction))
jurisdictionService.AddJurisdiction(jurisdiction)
End Using
End Sub
谁在呼叫getJurisdictionService
?只要呼叫者知道他们要求的类型,您就可以执行以下操作。
如何更改此内容:
Public Function getJurisdictionService(type As String) As Object
Return JurisdictionTypeMapper(type)
End Function
为此:
Public Function getJurisdictionService(Of T)() As IJurisdictionService(Of T)
Return DirectCast(JurisdictionTypeMapper(GetType(T)), IJurisdictionService(Of T))
End Function
并且调用者这样做是为了获得强类型的服务:
service = jurisdictionServiceFactory.getJurisdictionService(Of CountryJurisdictionService)()
当然,需要从Type而不是类名中键入字典:
Private JurisdictionTypeMapper As Dictionary(Of Type, Object)