将 Unity 依赖注入与 WCF 服务一起使用

Question

在对其他问题做了一些研究后，我有以下几点：

我的服务主机：

public class MyServiceHost : ServiceHost
{
    public MyServiceHost(IUnityContainer container, Type serviceType, params Uri[] baseAddresses)
        : base(serviceType, baseAddresses)
    {
        if (container == null)
        {
            throw new ArgumentNullException("container");
        }
        foreach (var cd in this.ImplementedContracts.Values)
        {
            cd.Behaviors.Add(new DependencyInjectionInstanceProvider(container));
        }
    }
}

DependencyInjectionInstanceProvider：

public class DependencyInjectionInstanceProvider : IInstanceProvider, IContractBehavior 
{     
    private readonly IUnityContainer container;      
    public DependencyInjectionInstanceProvider(IUnityContainer container)     
    {         
        if (container == null)         
        {             
            throw new ArgumentNullException("container");         
        }          

        this.container = container;     

    }      

    #region IInstanceProvider Members      

    public object GetInstance(InstanceContext instanceContext, Message message)     
    {         
        return this.GetInstance(instanceContext);     
    }      

    public object GetInstance(InstanceContext instanceContext)     
    {         
        var serviceType = instanceContext.Host.Description.ServiceType;         
        return this.container.Resolve(serviceType);     
    }      

    public void ReleaseInstance(InstanceContext instanceContext, object instance)    
    {        
        this.container.Teardown(instance);     
    }      

    #endregion      

    #region IContractBehavior Members      

    public void AddBindingParameters(ContractDescription contractDescription, ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)     
    {     
    }      

    public void ApplyClientBehavior(ContractDescription contractDescription, ServiceEndpoint endpoint, ClientRuntime clientRuntime)     
    {     
    }      

    public void ApplyDispatchBehavior(ContractDescription contractDescription, ServiceEndpoint endpoint, DispatchRuntime dispatchRuntime)    
    {         
        dispatchRuntime.InstanceProvider = this;     
    }      

    public void Validate(ContractDescription contractDescription, ServiceEndpoint endpoint)     
    {     
    }     
    #endregion 

} 

MyServiceHostFactory：

    public class MyServiceHostFactory : ServiceHostFactory
{
    private readonly IUnityContainer container;     
    protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses) 
    { 
        return new MyServiceHost(this.container, serviceType, baseAddresses); 
    }
}

尝试构造函数注入的电子邮件服务：

public class EmailValidator : IEmailValidator
{
    private IFakeDAL fakeDAL;

    public EmailValidator(IFakeDAL fakeDAL)
    {
        this.fakeDAL = fakeDAL;
    }

    public bool ValidateAddress(string emailAddress)
    {
        Console.WriteLine("Validating: {0}", emailAddress);

        string pattern = @"^([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@(([0-9a-zA-Z])+([-\w]*[0-9a-zA-Z])*\.)+[a-zA-Z]{2,9})$";
        return Regex.IsMatch(emailAddress, pattern);
    }
}

我的控制台主机启动服务：

static void Main(string[] args)
    {
        Type serviceType = typeof(EmailValidator);
        Uri serviceUri = new Uri("http://localhost:8080/");

        MyServiceHostFactory shf = new MyServiceHostFactory();
        ServiceHost host = shf.CreateServiceHost(serviceType, serviceUri);
        //ServiceHost host = new ServiceHost(serviceType, serviceUri);
        host.Open();

我的问题在于控制台主机逻辑。由于第一个参数需要构造函数字符串而不是类型，因此 CreateServiceHost 调用存在语法错误。我不明白，因为它确实接受 Type 参数。除此之外，我不明白应该将 IFakeDAL 映射到具体类的位置。我可以在 app.config 文件中执行此操作，还是应该在其他地方注册？

Answer 1

ServiceHostFactory 用于在 IIS 中托管。在自我托管中，您应该直接使用派生的ServiceHost。 Here 你有完整的例子，包括 Unity 配置。

Answer 2

我在我的 Windows 服务中使用以下类来创建 WCF 服务并使用统一向它注入依赖项。

UnityInstanceProvider：

internal class UnityInstanceProvider : IInstanceProvider {

    private readonly IUnityContainer container;
    private readonly Type contractType;

    public UnityInstanceProvider(IUnityContainer container, Type contractType) {
        this.container = container;
        this.contractType = contractType;
    }

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

    public object GetInstance(InstanceContext instanceContext, Message message) {
        return container.Resolve(contractType);
    }

    public void ReleaseInstance(InstanceContext instanceContext, object instance) {
        container.Teardown(instance);
    }
}

UnityServiceBehavior：

public class UnityServiceBehavior : IServiceBehavior {

    private readonly IUnityContainer container;

    public UnityServiceBehavior(IUnityContainer container) {
        this.container = container;
    }

    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 (ChannelDispatcher channelDispatcher in serviceHostBase.ChannelDispatchers) {
            foreach (EndpointDispatcher endpointDispatcher in channelDispatcher.Endpoints) {
                if (endpointDispatcher.ContractName != "IMetadataExchange") {
                    string contractName = endpointDispatcher.ContractName;
                    ServiceEndpoint serviceEndpoint = serviceDescription.Endpoints.FirstOrDefault(e => e.Contract.Name == contractName);
                    endpointDispatcher.DispatchRuntime.InstanceProvider = new UnityInstanceProvider(this.container, serviceEndpoint.Contract.ContractType);
                }
            }
        }
    }
}

UnityServiceHost：

public class UnityServiceHost : ServiceHost {

    private IUnityContainer unityContainer;

    public UnityServiceHost(IUnityContainer unityContainer, Type serviceType)
        : base(serviceType) {
        this.unityContainer = unityContainer;
    }

    protected override void OnOpening() {
        base.OnOpening();

        if (this.Description.Behaviors.Find<UnityServiceBehavior>() == null) {
            this.Description.Behaviors.Add(new UnityServiceBehavior(this.unityContainer));
        }
    }
}

使用这些类，您可以执行以下操作（服务的配置在 .config 中完成）：

UnityContainer container = new UnityContainer();
UnityServiceHost serviceHost = new UnityServiceHost(container, typeof("Type of Service to host"));
serviceHost.Open();

Answer 3

CreateServiceHost method 需要 Uri 实例的数组，因此请尝试以下操作：

ServiceHost host = shf.CreateServiceHost(serviceType, new[] { serviceUri });

您可以将接口映射到 XML 或代码中的类型，但我建议使用代码，因为 XML 的维护开销太高。

Main 方法是一个很好的Composition Root，但是如果你想在那个级别配置容器，你需要将它从Main 方法传递给MyServiceHostFactory - 这是非常好的您将服务托管在控制台应用程序中，但如果您想将其托管在 IIS 中，MyServiceHostFactoryshould be the Composition Root, since IIS requires a default constructor 将无法工作。