windowsphone7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*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：
[csharp]
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; 
        } 
    } 
}