c# - 尝试向我的 WCF 服务添加 IoC 支持

Question

我正在尝试将 IoC 支持添加到我的 REST WCF 服务 (Windows Server 2008)。我是新手，正在按照以下视频中提供的说明进行操作:

http://www.dimecasts.net/Content/WatchEpisode/150

该视频介绍了一些类，这些类帮助我在公开 WCF 端点时启动并运行 StructureMap 的 IoC。我已在本文末尾发布了所有代码。

当我运行我的代码时，自定义类 StructureMapServiceHost 在 StructureMapServiceHost(Type serviceType, params Uri[] baseAddress ) 方法中抛出错误:

   public class StructureMapServiceHost : ServiceHost
{
    public StructureMapServiceHost() {}

    public StructureMapServiceHost(Type serviceType, params Uri[] baseAddress)
        : base(serviceType, baseAddress)
    {

    }

    protected override void OnOpening()
    {
        Description.Behaviors.Add( new IoCServiceBehavior());
        base.OnOpening();
    }
}

有人告诉我:

提供的服务类型无法作为服务加载，因为它没有默认(无参数)构造函数。要解决此问题，请向类型添加默认构造函数，或将类型的实例传递给主机。

这是真的，它不是。但是视频示例也没有。以下是我的服务:

[ServiceBehavior(InstanceContextMode=InstanceContextMode.Single)]
    public class UserService : IUserService
    {
        public UserService(IUserRepository specification)
        {
            Specification = specification;
        }

        public List<User> GetAllUsers()
        {
            return Specification.GetAllUsers();
        }

        public User GetUser(string userId)
        {
            return Specification.GetUserById(new Guid(userId));
        }

        private List<User> SearchForUsers(string searchString)
        {
            return Specification.SearchUsers(searchString);
        }

        public IUserRepository Specification { get; set; }

    }



public class IoCServiceBehavior : IServiceBehavior
    {
        public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
        {   
        }

        public void AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, 
            Collection<ServiceEndpoint> endpoints, BindingParameterCollection bindingParameters)
        {
        }

        public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
        {
            foreach (ChannelDispatcherBase cdb in serviceHostBase.ChannelDispatchers)
            {
                new StructureMapInstanceProvider(serviceDescription.ServiceType);
            }
        }
    }


public class StructureMapInstanceProvider : IInstanceProvider
{
    private readonly Type _serviceType;

    public StructureMapInstanceProvider(Type serviceType)
    {
        _serviceType = serviceType;
    }

    public object GetInstance(InstanceContext instanceContext)
    {
        return GetInstance(instanceContext, null);
    }

    public object GetInstance(InstanceContext instanceContext, Message message)
    {
        var instance = ObjectFactory.GetInstance(_serviceType);

        return instance;
    }

    public void ReleaseInstance(InstanceContext instanceContext, object instance)
    {
        throw new NotImplementedException();
    }
}




public class StructureMapServiceHostFactory : ServiceHostFactory
    {
        public StructureMapServiceHostFactory()
        {
            IoCBootstrap.SetupIoc();
        }

        protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses)
        {
            return new StructureMapServiceHost(serviceType, baseAddresses);
        }
    }

有什么想法吗？谢谢。

编辑 ************ *************** *****

从我删除的 StructureMapServiceHost 中:

public StructureMapServiceHost(Type serviceType, params Uri[] baseAddress)
            : base(serviceType, baseAddress) { }

并添加:

public StructureMapServiceHost(Object singletonInstance, params Uri[] baseAddress)
            : base( singletonInstance, baseAddress) { }

然后从我的 UserService 构造函数中删除了参数。我没有收到错误消息:

The HTML document does not contain Web service discovery information.

Answer 1

您的服务使用 InstanceContextMode.SingleCall 并且 WCF 团队以他们无限的智慧决定，当 InstanceContextMode 为 SingleCall 时，不调用 IInstanceProvider 来创建实例(参见 https://learn.microsoft.com/en-us/archive/blogs/carlosfigueira/wcf-extensibility-iinstanceprovider - 接口(interface)声明标题下方的第二段)。

目前我在服务主机工厂中有一个不太理想的方法来解决这个问题:

using System;
using System.Collections.Generic;
using System.ServiceModel;
using System.ServiceModel.Activation;
using StructureMap;
using StructureMap.Pipeline;
using System.Linq;

using ServiceHostCreator = System.Func<System.Type, System.Uri[], System.ServiceModel.ServiceHost>;

namespace x.ServiceExtensions
{
    public class xWebServiceHostFactory : ServiceHostFactory
    {
        private readonly IDictionary<InstanceContextMode, ServiceHostCreator> _serviceHostCreators;

        public xWebServiceHostFactory()
        {
            ObjectFactory.Initialize( init =>
                                      init.Scan( scan =>
                                                     {
                                                         scan.AssembliesFromApplicationBaseDirectory();
                                                         scan.IgnoreStructureMapAttributes();
                                                         scan.LookForRegistries();
                                                     } ) );
            _serviceHostCreators = new Dictionary<InstanceContextMode, ServiceHostCreator>
                                        {
                                            { InstanceContextMode.PerCall, ( t, a ) => PerCallServiceHostCreator( t, a ) },
                                            { InstanceContextMode.PerSession, ( t, a ) => PerSessionServiceHostCreator( t, a ) },
                                            { InstanceContextMode.Single, ( t, a ) => SingleInstanceServiceHostCreator( t, a ) }
                                        };
        }

        protected override ServiceHost CreateServiceHost( Type serviceType, Uri[] baseAddresses )
        {
            var serviceInstanceContextMode = GetServiceInstanceContextMode( serviceType );
            var serviceHostCreator = _serviceHostCreators[ serviceInstanceContextMode ];
            return serviceHostCreator( serviceType, baseAddresses );
        }

        private static InstanceContextMode GetServiceInstanceContextMode( Type serviceType )
        {
            var serviceBehaviour = serviceType
                .GetCustomAttributes( typeof ( ServiceBehaviorAttribute ), true )
                .Cast<ServiceBehaviorAttribute>()
                .SingleOrDefault();
            return serviceBehaviour.InstanceContextMode;
        }

        private static ServiceHost PerCallServiceHostCreator( Type serviceType, Uri[] baseAddresses )
        {
            var args = new ExplicitArguments();
            args.Set( serviceType );
            args.Set( baseAddresses );
            var serviceHost = ObjectFactory.GetInstance<TelaWebServiceHost>( args );
            return serviceHost;
        }

        private static ServiceHost PerSessionServiceHostCreator( Type serviceType, Uri[] baseAddresses )
        {
            return PerCallServiceHostCreator( serviceType, baseAddresses );
        }

        private static ServiceHost SingleInstanceServiceHostCreator( Type serviceType, Uri[] baseAddresses )
        {
            var service = ObjectFactory.GetInstance( serviceType );
            var args = new ExplicitArguments();
            args.Set( typeof(object), service );
            args.Set( baseAddresses );
            var serviceHost = ObjectFactory.GetInstance<TelaWebServiceHost>( args );
            return serviceHost;
        }
    }
}

这是一项正在进行的工作，可能有更好的方法，但目前我找不到。