wcf 中 knowntype 属性的问题

Question

我的 wcf 客户端出现以下错误。

NetDispatcherFaultException 未处理。

格式化程序在尝试反序列化消息时抛出异常：尝试反序列化参数http://tempuri.org/:GetVehicleResult 时出错。 InnerException 消息是“第 1 行位置 266 中的错误。元素“http://tempuri.org/:GetVehicleResult”包含映射到名称“http://schemas.datacontract.org/2004/07/WCFServer:Car”的类型的数据。反序列化器不知道映射到此名称的任何类型。考虑使用 DataContractResolver 或将与“Car”对应的类型添加到已知类型列表中 - 例如，通过使用 KnownTypeAttribute 属性或将其添加到传递给 DataContractSerializer 的已知类型列表中。有关详细信息，请参阅 InnerException。

谁能帮我看看哪里错了。

WCF 服务器

---

IVehicle
--------
[ServiceContract]   
public interface IVehicleService
{
    [OperationContract]
    Vehicle GetVehicle(int type);

    [OperationContract]
    int GetNumberOfWheels(Vehicle vehicle);
}

车辆服务

---

[ServiceBehavior(AddressFilterMode = AddressFilterMode.Any)]   
public class VehicleService : IVehicleService
{        
    public Vehicle GetVehicle(int type)
    {
        switch (type)
        {
            case 0:
                return new Car()
                {
                   ID = 10,
                   Brand = "Volvo",
                   SteeringWheelPosition = "left"
                };

            case 1:
                return new bike()
                {
                    ID = 11,
                    Brand = "Scott",
                    HasFrontWheelBreak = true
                };

            case 2:
                return new Kidsbike()
                {
                    ID = 12,
                    Brand = "Kid Scott",
                    HasFrontWheelBreak = false,
                    HasSupportingWheels = true
                };

            default:
                return null;
        }
    }

    public int GetNumberOfWheels(Vehicle vehicle)
    {
        return vehicle.NoOfWheels;
    }
}

抽象类

---

[KnownType(typeof(Car))]
[KnownType(typeof(bike))]
[DataContract]
public abstract class Vehicle
{       
    [DataMember]
    public int ID { get; set; }

    abstract public int NoOfWheels { get; }

    [DataMember]
    public string Brand { get; set; }
}

具体类

---

[DataContract]
public class Car : Vehicle
{          
    override public int NoOfWheels { get { return 4; } }
    [DataMember]
    public string SteeringWheelPosition { get; set; }  
}

[KnownType(typeof(Kidsbike))]
[DataContract]
public class bike : Vehicle 
{           
    override public int NoOfWheels { get { return 2; } }
    [DataMember]
    public bool HasFrontWheelBreak { get; set; }  
}

[DataContract]
public class Kidsbike : bike
{
    [DataMember]
    public bool HasSupportingWheels { get; set; }  
}

WCF 客户端

---

namespace WCFClient
{
    [ServiceContract]   
    public interface IVehicleService
    {
        [OperationContract]       
        Vehicle GetVehicle(int type);

        [OperationContract]       
        int GetNumberOfWheels(Vehicle vehicle);
    } 
}

namespace WCFClient
{
    [KnownType(typeof(Car))]
    [KnownType(typeof(bike))]
    [DataContract]
    public abstract class Vehicle
    {
        [DataMember]
        public int ID { get; set; }

        abstract public int NoOfWheels { get; }
        [DataMember]
        public string Brand { get; set; }
    }
    [DataContract]
    public class Car : Vehicle
    {
        override public int NoOfWheels { get { return 0; } }
        [DataMember]
        public string SteeringWheelPosition { get; set; }
    }

    [KnownType(typeof(Kidsbike))]
    [DataContract]
    public class bike : Vehicle
    {
        override public int NoOfWheels { get { return 0; } }
        [DataMember]
        public bool HasFrontWheelBreak { get; set; }
    }
    [DataContract]
    public class Kidsbike : bike
    {
        [DataMember]
        public bool HasSupportingWheels { get; set; }
    }
}

private void btnGetVehicle_Click(object sender, EventArgs e)
{
    Car carObj = (Car)fclient.GetVehicle(0);          
}

只是在客户端创建代理。我可以成功调用该服务，但作为响应，我遇到了问题。我尝试使用 Knowntype 属性。这有什么问题。

Answer 1

以下代码可以正常工作，没有错误。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;

namespace WcfService1 {
    [ServiceKnownType(typeof(Car))]
    [ServiceKnownType(typeof(bike))]
    [ServiceKnownType(typeof(Kidsbike))]
    [ServiceContract]
    public interface IVehicleService {
        [OperationContract]
        Vehicle GetVehicle(int type);

        [OperationContract]
        int GetNumberOfWheels(Vehicle vehicle);
    }

      [DataContract]
    public abstract class Vehicle
    {
        [DataMember]
        public int ID { get; set; }

        abstract public int NoOfWheels { get; }
        [DataMember]
        public string Brand { get; set; }
    }
    [DataContract]
    public class Car : Vehicle
    {
        override public int NoOfWheels { get { return 0; } }
        [DataMember]
        public string SteeringWheelPosition { get; set; }
    }

    [KnownType(typeof(Kidsbike))]
    [DataContract]
    public class bike : Vehicle
    {
        override public int NoOfWheels { get { return 0; } }
        [DataMember]
        public bool HasFrontWheelBreak { get; set; }
    }
    [DataContract]
    public class Kidsbike : bike
    {
        [DataMember]
        public bool HasSupportingWheels { get; set; }
    }

[ServiceBehavior(AddressFilterMode = AddressFilterMode.Any)]   
public class VehicleService : IVehicleService
{        
    public Vehicle GetVehicle(int type)
    {
        switch (type)
        {
            case 0:
                return new Car()
                {
                   ID = 10,
                   Brand = "Volvo",
                   SteeringWheelPosition = "left"
                };

            case 1:
                return new bike()
                {
                    ID = 11,
                    Brand = "Scott",
                    HasFrontWheelBreak = true
                };

            case 2:
                return new Kidsbike()
                {
                    ID = 12,
                    Brand = "Kid Scott",
                    HasFrontWheelBreak = false,
                    HasSupportingWheels = true
                };

            default:
                return null;
        }
    }

    public int GetNumberOfWheels(Vehicle vehicle)
    {
        return vehicle.NoOfWheels;
    }
}

}

Svc 文件：

<%@ ServiceHost Language="C#" Debug="true" Service="WcfService1.VehicleService" CodeBehind="Service1.svc.cs" %>

测试服务：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;
using WcfService1;

namespace Test {
    class Program {
        static void Main(string[] args) {
            BasicHttpBinding hproxy = new BasicHttpBinding();
            hproxy.MaxReceivedMessageSize = 2147483647;
            hproxy.MaxBufferSize = 2147483647;
            hproxy.MaxBufferPoolSize = 2147483647;
            EndpointAddress eaddrr = new EndpointAddress("http://localhost:62807/Service1.svc");
            ChannelFactory<IVehicleService> CFactoryobj1 = new ChannelFactory<IVehicleService>(hproxy, eaddrr);
            IVehicleService isclientobj1 = CFactoryobj1.CreateChannel(); 
            Car ve = (Car)isclientobj1.GetVehicle(0);
        }
    }
}

Answer 2

KnownType 应该用在服务契约接口本身而不是车辆类上，因为它是为其一项操作返回 Vehicle 对象的类。我认为将 KnownType 添加到 Vehicle 类中没有任何作用。因为现在默认情况下，您不需要将 DataContract 添加到您的类中，它们就可以在 WCF 中使用。所以你应该有类似下面的东西。

[ServiceKnownType(typeof(Car))]
[ServiceKnownType(typeof(bike))]
[ServiceKnownType(typeof(Kidsbike))]
[ServiceContract]   
public interface IVehicleService
{
    [OperationContract]
    Vehicle GetVehicle(int type);

    [OperationContract]
    int GetNumberOfWheels(Vehicle vehicle);
}