答：通过实现 IClientMessageInspector，我能够在发送 XML 请求之前对其进行修改。
首先我必须通过实现 IClientMessageInspector 来扩展 WCF。这使我能够访问请求对象并修改 XML 请求消息。这些类不需要在您的解决方案中的任何特定位置（据我所知）。
public class ExtendedClientMessageInspector : IClientMessageInspector
{
// Here we can alter the xml request body before it gets sent out.
public object BeforeSendRequest(ref Message request, IClientChannel channel)
{
return TibcoService.ModifyGetLocationRequest(ref request);
} // end
public void AfterReceiveReply(ref Message reply, object correlationState)
{
return;
} //end
} // end class
public class ExtendedEndpointBehavior : IEndpointBehavior
{
public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
{
return;
} // end
public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
{
clientRuntime.MessageInspectors.Add(new ExtendedClientMessageInspector());
} // end
public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
{
return;
} // end
public void Validate(ServiceEndpoint endpoint)
{
return;
} // end
} // end class
public class EndpointBehaviorExtensionElement : BehaviorExtensionElement
{
protected override object CreateBehavior()
{
return new ExtendedEndpointBehavior();
} // end
public override Type BehaviorType
{
get
{
return typeof(ExtendedEndpointBehavior);
}
} // end
} // end class
我确实将 this 服务中专门处理 XML 的方法放在了与服务相同的类中：
public static Message ModifyGetLocationRequest(ref Message request)
{
// Initialize objects
var xmlDocument = new XmlDocument();
var memoryStream = new MemoryStream();
var xmlWriter = XmlWriter.Create(memoryStream);
var xmlAttribute = xmlDocument.CreateAttribute("xmlns", "api", "http://www.w3.org/2000/xmlns/");
xmlAttribute.Value = "http://customNamespaceHere";
// Write the xml request message into the memory stream
request.WriteMessage(xmlWriter);
// Clear the xmlWriter
xmlWriter.Flush();
// Place the pointer in the memoryStream to the beginning
memoryStream.Position = 0;
// Load the memory stream into the xmlDocument
xmlDocument.Load(memoryStream);
// Remove the attributes from the second node down form the top
xmlDocument.ChildNodes[1].ChildNodes[1].Attributes.RemoveAll();
// Reset the memoryStream object - essentially nulls it out
memoryStream.SetLength(0);
// ReInitialize the xmlWriter
xmlWriter = XmlWriter.Create(memoryStream);
// Write the modified xml request message (xmlDocument) to the memoryStream in the xmlWriter
xmlDocument.WriteTo(xmlWriter);
// Clear the xmlWriter
xmlWriter.Flush();
// Place the pointer in the memoryStream to the beginning
memoryStream.Position = 0;
// Create a new xmlReader with the memoryStream that contains the xmlDocument
var xmlReader = XmlReader.Create(memoryStream);
// Create a new request message with the modified xmlDocument
request = Message.CreateMessage(xmlReader, int.MaxValue, request.Version);
return request;
} // end
要在调用服务时让这一切正常工作，您需要修改 web.config 或 app.config。在您的端点声明中，您需要指定一个 behaviorConfiguration 元素，如下所示：
<client>
<endpoint address="http://1.2.3.4:1234/InventoryBinding"
binding="basicHttpBinding" bindingConfiguration="HttpSoapBinding"
contract="TibcoSvc.InventoryPort" name="InventoryPort"
behaviorConfiguration="clientInspectorsAdded" />
</client>
您还需要指定扩展名和行为：
<system.serviceModel>
<extensions>
<behaviorExtensions>
<add name="ExtendedEndpointBehavior" type="Sample.Integrations.EndpointBehaviorExtensionElement, Sample.Integrations, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null" />
</behaviorExtensions>
</extensions>
<behaviors>
<endpointBehaviors>
<behavior name="clientInspectorsAdded">
<ExtendedEndpointBehavior />
</behavior>
</endpointBehaviors>
</behaviors>
</system.serviceModel>
在此请注意，扩展名必须与所返回的完全一致：
var foo = typeof(<PutYourNamespaceHereNoAngleBrackets>.EndpointBehaviorExtensionElement).AssemblyQualifiedName;
这里有一些我觉得很有帮助的链接：
https://social.msdn.microsoft.com/Forums/vstudio/en-US/01440583-d406-4426-8667-63c6eda431fa/remove-xmlnsxsi-and-xmlnsxsd-from-soap-request-body-tag-aspnet?forum=wcf
https://social.msdn.microsoft.com/Forums/vstudio/en-US/51547537-fdae-4837-9bd1-30e445d378e9/removing-xmlnsxsihttpwwww3org2001xmlschemainstance-and?forum=wcf
http://weblogs.asp.net/paolopia/writing-a-wcf-message-inspector
https://msdn.microsoft.com/en-us/library/system.servicemodel.dispatcher.iclientmessageinspector(v=vs.100).aspx