C#客户端使用 http form的post方法提交图片

    using System;

    using System.Collections.Generic;

    using System.Linq;

    using System.Text;

    using System.Net;

    using System.IO;

namespace WpfApplication1  
{  
    public static class FormUpload  
    {  
        private static readonly Encoding encoding = Encoding.UTF8;  
        public static HttpWebResponse MultipartFormDataPost(string postUrl, string userAgent, Dictionary<string, object> postParameters)  
        {  
            string formDataBoundary = String.Format("----------{0:N}", Guid.NewGuid());  
            //string contentType = "multipart/form-data; boundary=" + formDataBoundary;  
            string contentType = "multipart/form-data; boundary=" + formDataBoundary;  


            byte[] formData = GetMultipartFormData(postParameters, formDataBoundary);  

            return PostForm(postUrl, userAgent, contentType, formData);  
        }  
        private static HttpWebResponse PostForm(string postUrl, string userAgent, string contentType, byte[] formData)  
        {  
            HttpWebRequest request = WebRequest.Create(postUrl) as HttpWebRequest;  

            if (request == null)  
            {  
                throw new NullReferenceException("request is not a http request");  
            }  

            // Set up the request properties.  
            request.Method = "POST";  
            request.ContentType = contentType;  
            request.UserAgent = userAgent;  
            request.CookieContainer = new CookieContainer();  
            request.ContentLength = formData.Length;  

            // You could add authentication here as well if needed:  
            // request.PreAuthenticate = true;  
            // request.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested;  
            // request.Headers.Add("Authorization", "Basic " + Convert.ToBase64String(System.Text.Encoding.Default.GetBytes("username" + ":" + "password")));  

            // Send the form data to the request.  
            using (Stream requestStream = request.GetRequestStream())  
            {  
                requestStream.Write(formData, 0, formData.Length);  
                requestStream.Close();  
            }  

            return request.GetResponse() as HttpWebResponse;  
        }  

        private static byte[] GetMultipartFormData(Dictionary<string, object> postParameters, string boundary)  
        {  
            Stream formDataStream = new System.IO.MemoryStream();  
            bool needsCLRF = false;  

            foreach (var param in postParameters)  
            {  
                // Thanks to feedback from commenters, add a CRLF to allow multiple parameters to be added.  
                // Skip it on the first parameter, add it to subsequent parameters.  
                if (needsCLRF)  
                    formDataStream.Write(encoding.GetBytes("\r\n"), 0, encoding.GetByteCount("\r\n"));  

                needsCLRF = true;  

                if (param.Value is FileParameter)  
                {  
                    FileParameter fileToUpload = (FileParameter)param.Value;  

                    // Add just the first part of this param, since we will write the file data directly to the Stream  
                    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");  

                    formDataStream.Write(encoding.GetBytes(header), 0, encoding.GetByteCount(header));  

                    // Write the file data directly to the Stream, rather than serializing it to a string.  
                    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(encoding.GetBytes(postData), 0, encoding.GetByteCount(postData));  
                }  
            }  

            // Add the end of the request.  Start with a newline  
            string footer = "\r\n--" + boundary + "--\r\n";  
            formDataStream.Write(encoding.GetBytes(footer), 0, encoding.GetByteCount(footer));  

            // Dump the Stream into a byte[]  
            formDataStream.Position = 0;  
            byte[] formData = new byte[formDataStream.Length];  
            formDataStream.Read(formData, 0, formData.Length);  
            formDataStream.Close();  

            return formData;  
        }  

        public class FileParameter  
        {  
            public byte[] File { get; set; }  
            public string FileName { get; set; }  
            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;  
            }  
        }  
    }  
}   </pre> 
 
 二、使用封装的类，提交数据（包含文本及图片） 
    Dictionary<string, object> postParameters = new Dictionary<string, object>();

            postParameters.Add("paramA", "value1");  
            postParameters.Add("paramB", "value2");  
            postParameters.Add("paramC", "value3");  

            postParameters.Add("picture", new FormUpload.FileParameter(data, "11.jpg", "image/jpg"));  

            // Create request and receive response  
            string postURL = global_ip + "service/PostImageAsBinty/";  
            string userAgent = "Someone";  
            HttpWebResponse webResponse = FormUpload.MultipartFormDataPost(postURL, userAgent, postParameters);  

            // Process response  
            StreamReader responseReader = new StreamReader(webResponse.GetResponseStream());  
            string fullResponse = responseReader.ReadToEnd();  
            webResponse.Close();  </pre>