朋友说开发电信的MMS，其实需要图片作为附件放在调用WebService接口上，使用Http的Content-Type: Multipart/Related;来发送，真让人感觉不伦不类的。不知道为什么不设计成一个字段是BASE64编码得了呗。

难道只能用朋友说的拼字段的方法了不？ 我用Reflect分析了一下，貌似这样也可以实现。

我们知道，我们添加一个WebService引用时，会自动生成从  SoapHttpClientProtocol 的子类。我的想法是，我们写一个 继承自"SoapHttpClientProtocol” 的子类SoapHttpClientProtocolEX, 重写方法：GetWebRequest() 返回我们写的代码 HttpWebRequestEx类，然后在原始 HttpWebRequest 类的GetRequestStream()时，返回我们的流转移器：NetwordStreamEx ，并在方法关闭流 Close() 前，加入自定义的附件信息。

不知道说清楚没有， 这里列了部分代码框架：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.Services.Protocols;
using System.Net;
using System.Net.Sockets;
using System.IO;namespace Foundway.Util.WebService
{public class SoapHttpClientProtocolEx : SoapHttpClientProtocol{private List<string> attachments = new List<string>();/// <summary>/// 添加一个附件/// </summary>/// <param name="attachment">附件全路径</param>public void AddAttachment(string attachment){attachments.Add(attachment);}protected override  WebRequest GetWebRequest(Uri uri){WebRequest request =   base.GetWebRequest(uri);if (attachments.Count > 0){HttpWebRequest httpRequest = request as HttpWebRequest;if (httpRequest != null){httpRequest.SendChunked = true; //使用多段发送HttpWebRequestEx httpRequestEx = new HttpWebRequestEx(httpRequest, attachments.ToArray());return httpRequestEx;}}return request;}}public class HttpWebRequestEx : WebRequest{private string[] attachments;private HttpWebRequest httpRequest = null;public HttpWebRequestEx(HttpWebRequest httpRequest, string[] attachments){this.httpRequest = httpRequest;this.attachments = attachments;}public override System.IO.Stream GetRequestStream(){Stream stream = httpRequest.GetRequestStream();//返回自定义的流代理，来完成附件的信息return new NetworkStreamEx(stream, this.attachments);}#region 重写其它全部公共方法public override void Abort(){httpRequest.Abort();}public override IAsyncResult BeginGetRequestStream(AsyncCallback callback, object state){return httpRequest.BeginGetRequestStream(callback, state);}public override IAsyncResult BeginGetResponse(AsyncCallback callback, object state){return httpRequest.BeginGetResponse(callback, state);}public override System.Net.Cache.RequestCachePolicy CachePolicy{get{return httpRequest.CachePolicy;}set{httpRequest.CachePolicy = value;}}public override string ConnectionGroupName{get{return httpRequest.ConnectionGroupName;}set{httpRequest.ConnectionGroupName = value;}}public override long ContentLength{get{return httpRequest.ContentLength;}set{httpRequest.ContentLength = value;}}public override string ContentType{get{return httpRequest.ContentType;}set{httpRequest.ContentType = value;}}public override System.Runtime.Remoting.ObjRef CreateObjRef(Type requestedType){return httpRequest.CreateObjRef(requestedType);}public override ICredentials Credentials{get{return httpRequest.Credentials;}set{httpRequest.Credentials = value;}}public override Stream EndGetRequestStream(IAsyncResult asyncResult){return httpRequest.EndGetRequestStream(asyncResult);}public override WebResponse EndGetResponse(IAsyncResult asyncResult){return httpRequest.EndGetResponse(asyncResult);}public override WebResponse GetResponse(){return httpRequest.GetResponse();}public override WebHeaderCollection Headers{get{return httpRequest.Headers;}set{httpRequest.Headers = value;}}public override string Method{get{return httpRequest.Method;}set{httpRequest.Method = value;}}public override bool PreAuthenticate{get{return httpRequest.PreAuthenticate;}set{httpRequest.PreAuthenticate = value;}}public override IWebProxy Proxy{get{return httpRequest.Proxy;}set{httpRequest.Proxy = value;}}public override object InitializeLifetimeService(){return httpRequest.InitializeLifetimeService();}public override Uri RequestUri{get{return httpRequest.RequestUri;}}public override int Timeout{get{return httpRequest.Timeout;}set{httpRequest.Timeout = value;}}public override string ToString(){return httpRequest.ToString();}public override bool UseDefaultCredentials{get{return httpRequest.UseDefaultCredentials;}set{httpRequest.UseDefaultCredentials = value;}}public override bool Equals(object obj){return httpRequest.Equals(obj);}public override int GetHashCode(){return httpRequest.GetHashCode();}#endregion}public class NetworkStreamEx :Stream{private string[] attachments;private Stream baseStream;public NetworkStreamEx(Stream baseStream, string[] attachments){this.baseStream = baseStream;}/// <summary>/// 在关闭时，加入附件信息/// </summary>public override void Close(){///TODO:这里添加附件信息，///这里就不加代码了///base.Close();}#region 把其它公共方法转发到原流public override bool CanRead{get { return baseStream.CanRead; }}public override bool CanSeek{get { return baseStream.CanSeek; }}public override bool CanWrite{get { return baseStream.CanWrite; }}public override void Flush(){baseStream.Flush();}public override long Length{get { return baseStream.Length; }}public override long Position{get{return baseStream.Position;}set{baseStream.Position  = value;}}public override int Read(byte[] buffer, int offset, int count){return baseStream.Read(buffer, offset, count);}public override long Seek(long offset, SeekOrigin origin){return baseStream.Seek(offset, origin);}public override void SetLength(long value){baseStream.SetLength(value);}public override void Write(byte[] buffer, int offset, int count){baseStream.Write(buffer, offset, count);}#endregion}}

引自：51aspx