已知类型

2025-06-19

KnownTypes 示例演示如何在数据协定中指定有关派生类型的信息。数据协定允许你向/从服务传递结构化数据。在面向对象的编程中，继承自其他类型的类型可用于代替原始类型。在面向服务的编程中，将传达架构而不是类型，因此，不会保留类型之间的关系。该 KnownTypeAttribute 属性允许在数据协定中包含有关派生类型的信息。如果未使用此机制，则不能在需要基类型的情况下发送或接收派生类型。

注释

本示例的设置过程和生成说明位于本主题末尾。

服务的服务协定使用复数，如以下示例代码所示。

// Define a service contract.
[ServiceContract(Namespace="http://Microsoft.ServiceModel.Samples")]
public interface ICalculator
{
    [OperationContract]
    ComplexNumber Add(ComplexNumber n1, ComplexNumber n2);
    [OperationContract]
    ComplexNumber Subtract(ComplexNumber n1, ComplexNumber n2);
    [OperationContract]
    ComplexNumber Multiply(ComplexNumber n1, ComplexNumber n2);
    [OperationContract]
    ComplexNumber Divide(ComplexNumber n1, ComplexNumber n2);
}

DataContractAttribute和DataMemberAttribute应用于ComplexNumber类，以指示该类中哪些字段可以在客户端和服务之间传递。派生 ComplexNumberWithMagnitude 类可用于代替 ComplexNumber。类型 KnownTypeAttribute 上的 ComplexNumber 属性指示这一点。

[DataContract(Namespace="http://Microsoft.ServiceModel.Samples")]
[KnownType(typeof(ComplexNumberWithMagnitude))]
public class ComplexNumber
{
    [DataMember]
    public double Real = 0.0D;
    [DataMember]
    public double Imaginary = 0.0D;

    public ComplexNumber(double real, double imaginary)
    {
        this.Real = real;
        this.Imaginary = imaginary;
    }
}

类型ComplexNumberWithMagnitude派生自ComplexNumber但添加其他数据成员。 Magnitude

[DataContract(Namespace="http://Microsoft.ServiceModel.Samples")]
public class ComplexNumberWithMagnitude : ComplexNumber
{
    public ComplexNumberWithMagnitude(double real, double imaginary) :
        base(real, imaginary) { }

    [DataMember]
    public double Magnitude
    {
        get { return Math.Sqrt(Imaginary*Imaginary  + Real*Real); }
        set { throw new NotImplementedException(); }
    }
}

为了演示已知类型功能，该服务的实现方式是仅在加法和减法时返回 ComplexNumberWithMagnitude。（尽管协定指定 ComplexNumber，但由于 KnownTypeAttribute 属性，允许这样做）。乘法和除法仍返回基 ComplexNumber 类型。

public class DataContractCalculatorService : IDataContractCalculator
{
    public ComplexNumber Add(ComplexNumber n1, ComplexNumber n2)
    {
        //Return the derived type.
        return new ComplexNumberWithMagnitude(n1.Real + n2.Real,
                                      n1.Imaginary + n2.Imaginary);
    }

    public ComplexNumber Subtract(ComplexNumber n1, ComplexNumber n2)
    {
        //Return the derived type.
        return new ComplexNumberWithMagnitude(n1.Real - n2.Real,
                                 n1.Imaginary - n2.Imaginary);
    }

    public ComplexNumber Multiply(ComplexNumber n1, ComplexNumber n2)
    {
        double real1 = n1.Real * n2.Real;
        double imaginary1 = n1.Real * n2.Imaginary;
        double imaginary2 = n2.Real * n1.Imaginary;
        double real2 = n1.Imaginary * n2.Imaginary * -1;
        //Return the base type.
        return new ComplexNumber(real1 + real2, imaginary1 +
                                                  imaginary2);
    }

    public ComplexNumber Divide(ComplexNumber n1, ComplexNumber n2)
    {
        ComplexNumber conjugate = new ComplexNumber(n2.Real,
                                     -1*n2.Imaginary);
        ComplexNumber numerator = Multiply(n1, conjugate);
        ComplexNumber denominator = Multiply(n2, conjugate);
        //Return the base type.
        return new ComplexNumber(numerator.Real / denominator.Real,
                                             numerator.Imaginary);
    }
}

在客户端上，服务协定和数据协定都在源文件generatedClient.cs中定义，这是由 ServiceModel 元数据实用工具工具（Svcutil.exe）从服务元数据生成的。由于属性 KnownTypeAttribute 是在服务的数据协定中指定的，因此客户端在使用服务时能够接收 ComplexNumber 和 ComplexNumberWithMagnitude 类。客户端检测它是否获得了 ComplexNumberWithMagnitude 并生成相应的输出：

// Create a client
DataContractCalculatorClient client =
    new DataContractCalculatorClient();

// Call the Add service operation.
ComplexNumber value1 = new ComplexNumber() { real = 1, imaginary = 2 };
ComplexNumber value2 = new ComplexNumber() { real = 3, imaginary = 4 };
ComplexNumber result = client.Add(value1, value2);
Console.WriteLine("Add({0} + {1}i, {2} + {3}i) = {4} + {5}i",
    value1.real, value1.imaginary, value2.real, value2.imaginary,
    result.real, result.imaginary);
if (result is ComplexNumberWithMagnitude)
{
    Console.WriteLine("Magnitude: {0}",
        ((ComplexNumberWithMagnitude)result).Magnitude);
}
else
{
    Console.WriteLine("No magnitude was sent from the service");
}

运行示例时，作的请求和响应将显示在客户端控制台窗口中。请注意，由于服务的实现方式，打印了一个数量级，用于加法和减法，但不用于乘法和除法。在客户端窗口中按 Enter 关闭客户端。

Add(1 + 2i, 3 + 4i) = 4 + 6i
Magnitude: 7.21110255092798
Subtract(1 + 2i, 3 + 4i) = -2 + -2i
Magnitude: 2.82842712474619
Multiply(2 + 3i, 4 + 7i) = -13 + 26i
No magnitude was sent from the service
Divide(3 + 7i, 5 + -2i) = 0.0344827586206897 + 41i
No magnitude was sent from the service

    Press <ENTER> to terminate client.

设置、生成和运行示例

确保已为 Windows Communication Foundation 示例执行One-Time 安装过程。
若要生成解决方案的 C# 或 Visual Basic .NET 版本，请按照生成 Windows Communication Foundation 示例中的说明进行操作。
若要在单台计算机或跨计算机配置中运行示例，请按照运行 Windows Communication Foundation 示例中的说明进行操作。

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