利用HttpWebRequest模拟表单提交

 using System;
 using System.Collections.Specialized;
 using System.IO;
 using System.Net;
 using System.Text;

 namespace Allyn.Common
 {
     public class HttpHelper
     {
         /// <summary>
         /// 获取指定路径数据
         /// </summary>
         /// <param name="requestUri">提交路径</param>
         /// <param name="cookie">Cookie容器对象</param>
         /// <returns>字符串结果</returns>
         public static string GetForm(string requestUri, CookieContainer cookie)
         {
             HttpWebRequest request = WebRequest.CreateHttp(requestUri);
             request.Method = "get";
             request.CookieContainer = cookie;
             request.ContentLength = ;

             WebResponse response = request.GetResponse();
             StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
             return reader.ReadToEnd();
         }

         /// <summary>
         /// 默认表单提交
         /// </summary>
         /// <param name="requestUri">提交路径</param>
         /// <param name="postData">提交数据</param>
         /// <param name="cookie">Cookie容器对象</param>
         /// <returns>字符串结果</returns>
         public static string PostForm(string requestUri, NameValueCollection postData, CookieContainer cookie)
         {
             HttpWebRequest request = WebRequest.CreateHttp(requestUri);
             request.Method = "post";
             request.ContentType = "application/x-www-form-urlencoded";
             request.CookieContainer = cookie;

             StringBuilder stringBuilder = new StringBuilder();
             foreach (string key in postData.Keys)
             {
                 stringBuilder.AppendFormat("&{0}={1}", key, postData.Get(key));
             }
             byte[] buffer = Encoding.UTF8.GetBytes(stringBuilder.ToString().Trim('&'));
             Stream requestStream = request.GetRequestStream();
             requestStream.Write(buffer, , buffer.Length);
             requestStream.Close();

             WebResponse response = request.GetResponse();
             StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
             return reader.ReadToEnd();
         }

         /// <summary>
         /// 多部件表单提交
         /// </summary>
         /// <param name="requestUri">提交路径</param>
         /// <param name="postData">提交数据.注:如果是文件路径,代表是文件.</param>
         /// <param name="cookie">Cookie容器对象</param>
         /// <returns>字符串结果</returns>
         public static string PostFormMultipart(string requestUri, NameValueCollection postData, CookieContainer cookie)
         {
             string boundary = string.Format("-----{0}", DateTime.Now.Ticks.ToString("x"));
             HttpWebRequest webrequest = WebRequest.CreateHttp(requestUri);
             webrequest.CookieContainer = cookie;
             webrequest.Timeout = ;
             webrequest.Method = "post";
             webrequest.ContentType = string.Format("multipart/form-data; boundary={0}", boundary);

             Stream requestStream = webrequest.GetRequestStream();
             foreach (string key in postData.Keys)
             {
                 StringBuilder strBuilder = new StringBuilder();
                 strBuilder.AppendFormat("--{0}", boundary);
                 strBuilder.AppendFormat("\r\nContent-Disposition: form-data; name=\"{0}\"", key);
                 if (File.Exists(postData.Get(key)))
                 {
                     strBuilder.AppendFormat(";filename=\"{0}\"\r\nContent-Type: multipart/form-data\r\n\r\n", Path.GetFileName(postData.Get(key)));
                     byte[] buffer = Encoding.UTF8.GetBytes(strBuilder.ToString());
                     requestStream.Write(buffer, , buffer.Length);
                     //获取图片流
                     FileStream fileStream = new FileStream(postData.Get(key), FileMode.Open, FileAccess.Read);
                     BinaryReader binaryReader = new BinaryReader(fileStream);
                     byte[] fileBuffer = binaryReader.ReadBytes((int)fileStream.Length);
                     binaryReader.Close();
                     fileStream.Close();
                     requestStream.Write(fileBuffer, , fileBuffer.Length);
                 }
                 else
                 {
                     strBuilder.AppendFormat("\r\n\r\n{0}\r\n", postData.Get(key));
                     byte[] buff = Encoding.UTF8.GetBytes(strBuilder.ToString());
                     requestStream.Write(buff, , buff.Length);
                 }
             }

             byte[] boundaryBuffer = Encoding.UTF8.GetBytes(string.Format("\r\n--{0}\r\n", boundary));
             requestStream.Write(boundaryBuffer, , boundaryBuffer.Length);
             requestStream.Close();

             WebResponse response = webrequest.GetResponse();
             StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
             return reader.ReadToEnd();
         }
     }
 }