ServiceKnownTypeAttribute Classe

Definição

public ref class ServiceKnownTypeAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.Class | System.AttributeTargets.Interface | System.AttributeTargets.Method, AllowMultiple=true, Inherited=true)]
public sealed class ServiceKnownTypeAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Class | System.AttributeTargets.Interface | System.AttributeTargets.Method, AllowMultiple=true, Inherited=true)>]
type ServiceKnownTypeAttribute = class
    inherit Attribute

Public NotInheritable Class ServiceKnownTypeAttribute
Inherits Attribute

Herança

Object

Attribute

ServiceKnownTypeAttribute

Atributos

AttributeUsageAttribute

Exemplos

O exemplo a seguir aplica o ServiceKnownTypeAttribute atributo a uma interface em que o atributo especifica um nome de método e um tipo de declaração.

// Define a service contract and apply the ServiceKnownTypeAttribute
// to specify types to include when generating client code.
// The types must have the DataContractAttribute and DataMemberAttribute
// applied to be serialized and deserialized. The attribute specifies the
// name of a method (GetKnownTypes) in a class (Helper) defined below.
[ServiceKnownType("GetKnownTypes", typeof(Helper))]
[ServiceContract()]
public interface ICatalog
{
    // Any object type can be inserted into a Hashtable. The
    // ServiceKnownTypeAttribute allows you to include those types
    // with the client code.
    [OperationContract]
    Hashtable GetItems();
}

// This class has the method named GetKnownTypes that returns a generic IEnumerable.
static class Helper
{
    public static IEnumerable<Type> GetKnownTypes(ICustomAttributeProvider provider)
    {
        System.Collections.Generic.List<System.Type> knownTypes =
            new System.Collections.Generic.List<System.Type>();
        // Add any types to include here.
        knownTypes.Add(typeof(Widget));
        knownTypes.Add(typeof(Machine));
        return knownTypes;
    }
}

[DataContract()]
public class Widget
{
    [DataMember]
    public string Id;
    [DataMember]
    public string Catalog;
}

[DataContract()]
public class Machine : Widget
{
    [DataMember]
    public string Maker;
}

' Define a service contract and apply the ServiceKnownTypeAttribute
' to specify types to include when generating client code. 
' The types must have the DataContractAttribute and DataMemberAttribute
' applied to be serialized and deserialized. The attribute specifies the 
' name of a method (GetKnownTypes) in a class (Helper) defined below.
<ServiceKnownType("GetKnownTypes", GetType(Helper)), ServiceContract()>  _
Public Interface ICalculator
    ' Any object type can be inserted into a Hashtable. The 
    ' ServiceKnownTypeAttribute allows you to include those types
    ' with the client code.
    <OperationContract()>  _
    Function GetItems() As Hashtable 
End Interface 

' This class has the method named GetKnownTypes that returns a generic IEnumerable.
Friend Class Helper
    Public Shared  Function GetKnownTypes(provider As ICustomAttributeProvider) _
     As IEnumerable(of Type) 
        Dim knownTypes As List(Of Type) = New List(Of Type)
        ' Add any types to include here.
        knownTypes.Add(GetType(Widget))
        knownTypes.Add(GetType(Machine))
        Return knownTypes
    End Function 
End Class 

<DataContract()>  _
Public Class Widget
    <DataMember()>  _
    Public Id As String
    <DataMember()>  _
    Public Catalog As String
End Class 

<DataContract()>  _
Public Class Machine
    Inherits Widget
    <DataMember()>  _
    Public Maker As String
End Class

Como alternativa, aplique o atributo à interface que especifica o tipo conhecido a ser incluído.

// Apply the ServiceKnownTypeAttribute to the
// interface specifying the type to include. Apply
// the attribute more than once if needed.
[ServiceKnownType(typeof(Widget))]
[ServiceKnownType(typeof(Machine))]
[ServiceContract()]
public interface ICatalog2
{
    // Any object type can be inserted into a Hashtable. The
    // ServiceKnownTypeAttribute allows you to include those types
    // with the client code.
    [OperationContract]
    Hashtable GetItems();
}

' Apply the ServiceKnownTypeAttribute to the 
' interface specifying the type to include. Apply the attribute
' more than once, if needed.
<ServiceKnownType(GetType(Widget)), ServiceKnownType(GetType(Machine)), _
 ServiceContract()>  _
Public Interface ICalculator2
    ' Any object type can be inserted into a Hashtable. The 
    ' ServiceKnownTypeAttribute allows you to include those types
    ' with the client code.
    <OperationContract()>  _
    Function GetItems() As Hashtable 
End Interface

Comentários

O ServiceKnownTypeAttribute objetivo é usar ao criar contratos de serviço do WCF (Windows Communication Foundation) (interfaces que definem o serviço e seus métodos). Os tipos conhecidos são tipos que podem estar presentes em um grafo de objeto quando ocorre a serialização ou desserialização. Para obter mais informações sobre tipos conhecidos, consulte Tipos Conhecidos do Contrato de Dados.

Para usar a MethodName propriedade, crie uma classe que contenha um método (ou métodos) que retorna uma matriz de tipos (cada um sendo um tipo conhecido). Ao aplicar o atributo, defina o methodName nome de um método que retorna a lista de tipos e defina o declaringType tipo que contém o método. O método deve retornar um tipo que implemente a IEnumerable<T> interface. O método também deve incluir um parâmetro do tipo ICustomAttributeProvider.

Você também pode aplicar o atributo várias vezes a uma interface, classe ou método, sempre que especificar um novo tipo conhecido.

Construtores

Propriedades

Métodos

Implantações explícitas de interface

Aplica-se a

Confira também

• DataContractAttribute
• DataMemberAttribute
• Tipos de contratos de dados conhecidos