需要实现 MessageHeaders.WriteHeaderContents 的示例

Question

我有一个存储在“字符串”变量中的自定义标头，我需要用“字符串”类型变量中的标头替换来自我的 WCF 客户端的传出 SOAP 请求的标头。根据研究，我发现实现MessageHeaders.WriteHeaderContents可以工作，但此方法仅接受XmlDictionaryWriter或XmlWriter输入作为输入。我有一个字符串输入。我如何在 C# 中编码..

Answer 1

消息头是一个 SOAP 概念，而 SOAP 请求是 XML 文档，因此您确实需要一些 XML 特性。但是对于您的场景，您实际上不需要覆盖MessageHeaders，您可以使用检查器并在此时简单地替换标头，如下面的示例所示（转换为 XML 将由MessageHeader类完成）。

public class StackOverflow_7141998
{
    [MessageContract]
    public class MyMC
    {
        [MessageHeader(Name = "MyHeader", Namespace = "http://my.namespace.com")]
        public string HeaderValue { get; set; }
        [MessageBodyMember(Name = "MyBody", Namespace = "http://my.namespace.com")]
        public string BodyValue { get; set; }
    }
    [ServiceContract]
    public interface ITest
    {
        [OperationContract]
        void Process(MyMC mc);
    }
    public class Service : ITest
    {
        public void Process(MyMC mc)
        {
            Console.WriteLine("Header value: {0}", mc.HeaderValue);
        }
    }
    public class MyInspector : IEndpointBehavior, IClientMessageInspector
    {
        public string NewHeaderValue { get; set; }

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

        public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
        {
            clientRuntime.MessageInspectors.Add(this);
        }

        public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
        {
        }

        public void Validate(ServiceEndpoint endpoint)
        {
        }

        public void AfterReceiveReply(ref Message reply, object correlationState)
        {
        }

        public object BeforeSendRequest(ref Message request, IClientChannel channel)
        {
            int originalIndex = request.Headers.FindHeader("MyHeader", "http://my.namespace.com");
            if (originalIndex >= 0)
            {
                request.Headers.Insert(originalIndex, MessageHeader.CreateHeader("MyHeader", "http://my.namespace.com", this.NewHeaderValue));
                request.Headers.RemoveAt(originalIndex + 1);
            }

            return null;
        }
    }
    public static void Test()
    {
        string baseAddress = "http://" + Environment.MachineName + ":8000/Service";
        ServiceHost host = new ServiceHost(typeof(Service), new Uri(baseAddress));
        ServiceEndpoint endpoint = host.AddServiceEndpoint(typeof(ITest), new WSHttpBinding(), "");
        host.Open();
        Console.WriteLine("Host opened");

        ChannelFactory<ITest> factory = new ChannelFactory<ITest>(new WSHttpBinding(), new EndpointAddress(baseAddress));
        MyInspector inspector = new MyInspector { NewHeaderValue = "Modified header value" };
        factory.Endpoint.Behaviors.Add(inspector);
        ITest proxy = factory.CreateChannel();

        proxy.Process(new MyMC { HeaderValue = "Original header value", BodyValue = "The body" });

        ((IClientChannel)proxy).Close();
        factory.Close();

        Console.Write("Press ENTER to close the host");
        Console.ReadLine();
        host.Close();
    }
}