Windows Phone7 实现文件上传

在基于Http协议的Post请求中，Content-type为application/x-www-form-urlencoded的传输只能传送非文件的数据。

如果想用Http的Post方法来上传数据及文件，需要实现Content-type为multipart/form-data类型的协议程序。

下面是参考了StackOverflow网站上的一个例子，实现了关于客户端上传文件的功能类，代码如下：

using System;  using System.Net;  using System.Text;  using System.Collections.Generic;  using System.IO;    namespace ZDWorks.ZDClock.Cloud  {      /// <summary>      /// 文件类型数据的内容参数      /// </summary>      public class FileParameter      {          // 文件内容          public byte[] File { get; set; }          // 文件名          public string FileName { get; set; }          // 文件内容类型          public string ContentType { get; set; }            public FileParameter(byte[] file) : this(file, null) { }            public FileParameter(byte[] file, string filename) : this(file, filename, null) { }            public FileParameter(byte[] file, string filename, string contentType)          {              File = file;              FileName = filename;              ContentType = contentType;          }      }        /// <summary>      /// 数据与文件http请求      /// </summary>      public class HttpMultipartFormRequest      {          #region Data Members            private readonly Encoding DefaultEncoding = Encoding.UTF8;          private ResponseCallback m_Callback;          private byte[] m_FormData;            #endregion            #region Constructor            public HttpMultipartFormRequest()          {           }            #endregion            #region Delegate            public delegate void ResponseCallback(string msg);            #endregion            public void AsyncHttpRequest(string postUri, Dictionary<string, object> postParameters, ResponseCallback callback)          {              // 随机序列，用作防止服务器无法识别数据的起始位置              string formDataBoundary = String.Format("----------{0:N}", Guid.NewGuid());              // 设置contentType              string contentType = "multipart/form-data; boundary=" + formDataBoundary;              // 将数据转换为byte[]格式              m_FormData = GetMultipartFormData(postParameters, formDataBoundary);              // 回调函数              m_Callback = callback;                // 创建http对象              HttpWebRequest request = HttpWebRequest.CreateHttp(new Uri(postUri));              // 设为post请求              request.Method = "POST";              request.ContentType = contentType;              // 请求写入数据流              request.BeginGetRequestStream(GetRequestStreamCallback, request);          }            private void GetRequestStreamCallback(IAsyncResult ar)          {              HttpWebRequest request = ar.AsyncState as HttpWebRequest;              using (var postStream = request.EndGetRequestStream(ar))              {                  postStream.Write(m_FormData, 0, m_FormData.Length);                  postStream.Close();              }              request.BeginGetResponse(GetResponseCallback, request);          }            private void GetResponseCallback(IAsyncResult ar)          {              // 处理Post请求返回的消息              try              {                  HttpWebRequest request = ar.AsyncState as HttpWebRequest;                  HttpWebResponse response = request.EndGetResponse(ar) as HttpWebResponse;                  using (var stream = response.GetResponseStream())                  {                      StreamReader reader = new StreamReader(stream);                      string msg = reader.ReadToEnd();                        if (m_Callback != null)                      {                          m_Callback(msg);                      }                  }              }              catch (Exception e)              {                  string a = e.ToString();                  if (m_Callback != null)                  {                      m_Callback(string.Empty);                  }              }          }            private byte[] GetMultipartFormData(Dictionary<string, object> postParameters, string boundary)          {              Stream formDataStream = new MemoryStream();              bool needsCLRF = false;                foreach (var param in postParameters)              {                  if (needsCLRF)                  {                      formDataStream.Write(DefaultEncoding.GetBytes("\r\n"), 0, DefaultEncoding.GetByteCount("\r\n"));                  }                  needsCLRF = true;                    if (param.Value is FileParameter)                  {                      FileParameter fileToUpload = (FileParameter)param.Value;                        string header = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"; filename=\"{2}\";\r\nContent-Type: {3}\r\n\r\n",                          boundary,                          param.Key,                          fileToUpload.FileName ?? param.Key,                          fileToUpload.ContentType ?? "application/octet-stream");                        // 将与文件相关的header数据写到stream中                      formDataStream.Write(DefaultEncoding.GetBytes(header), 0, DefaultEncoding.GetByteCount(header));                      // 将文件数据直接写到stream中                      formDataStream.Write(fileToUpload.File, 0, fileToUpload.File.Length);                  }                  else                  {                      string postData = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"\r\n\r\n{2}",                          boundary,                          param.Key,                          param.Value);                      formDataStream.Write(DefaultEncoding.GetBytes(postData), 0, DefaultEncoding.GetByteCount(postData));                  }              }                string tailEnd = "\r\n--" + boundary + "--\r\n";              formDataStream.Write(DefaultEncoding.GetBytes(tailEnd), 0, DefaultEncoding.GetByteCount(tailEnd));                // 将Stream数据转换为byte[]格式              formDataStream.Position = 0;              byte[] formData = new byte[formDataStream.Length];              formDataStream.Read(formData, 0, formData.Length);              formDataStream.Close();                return formData;          }      }  }