.net后台webclient用post方式发送文件和数据

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Text;
using System.Net;
 
namespace BcpMobile.Handlers
{
    /// <summary>
    /// description：http post请求客户端
    /// last-modified-date：2012-02-28
    /// </summary>
    public class HttpRequestClient
    {
        #region //字段
        private ArrayList bytesArray;
        private Encoding encoding = Encoding.UTF8;
        private string boundary = String.Empty;
        #endregion
 
        #region //构造方法
        public HttpRequestClient()
        {
            bytesArray = new ArrayList();
            string flag = DateTime.Now.Ticks.ToString("x");
            boundary = "---------------------------" + flag;
        }
        #endregion
 
        #region //方法
        /// <summary>
        /// 合并请求数据
        /// </summary>
        /// <returns></returns>
        private byte[] MergeContent()
        {
            int length = 0;
            int readLength = 0;
            string endBoundary = "--" + boundary + "--
";
            byte[] endBoundaryBytes = encoding.GetBytes(endBoundary);
 
            bytesArray.Add(endBoundaryBytes);
 
            foreach (byte[] b in bytesArray)
            {
                length += b.Length;
            }
 
            byte[] bytes = new byte[length];
 
            foreach (byte[] b in bytesArray)
            {
                b.CopyTo(bytes, readLength);
                readLength += b.Length;
            }
 
            return bytes;
        }
 
        /// <summary>
        /// 上传
        /// </summary>
        /// <param name="requestUrl">请求url</param>
        /// <param name="responseText">响应</param>
        /// <returns></returns>
        public bool Upload(String requestUrl, out String responseText)
        {
            WebClient webClient = new WebClient();
            webClient.Headers.Add("Content-Type", "multipart/form-data; boundary=" + boundary);
 
            byte[] responseBytes;
            byte[] bytes = MergeContent();
 
            try
            {
                responseBytes = webClient.UploadData(requestUrl, bytes);
                responseText = System.Text.Encoding.UTF8.GetString(responseBytes);
                return true;
            }
            catch (WebException ex)
            {
                Stream responseStream = ex.Response.GetResponseStream();
                responseBytes = new byte[ex.Response.ContentLength];
                responseStream.Read(responseBytes, 0, responseBytes.Length);
            }
            responseText = System.Text.Encoding.UTF8.GetString(responseBytes);
            return false;
        }
 
        /// <summary>
        /// 设置表单数据字段
        /// </summary>
        /// <param name="fieldName">字段名</param>
        /// <param name="fieldValue">字段值</param>
        /// <returns></returns>
        public void SetFieldValue(String fieldName, String fieldValue)
        {
            string httpRow = "--" + boundary + "
Content-Disposition: form-data; name="{0}"

{1}
";
            string httpRowData = String.Format(httpRow, fieldName, fieldValue);
 
            bytesArray.Add(encoding.GetBytes(httpRowData));
        }
 
        /// <summary>
        /// 设置表单文件数据
        /// </summary>
        /// <param name="fieldName">字段名</param>
        /// <param name="filename">字段值</param>
        /// <param name="contentType">内容内型</param>
        /// <param name="fileBytes">文件字节流</param>
        /// <returns></returns>
        public void SetFieldValue(String fieldName, String filename, String contentType, Byte[] fileBytes)
        {
            string end = "
";
            string httpRow = "--" + boundary + "
Content-Disposition: form-data; name="{0}"; filename="{1}"
Content-Type: {2}

";
            string httpRowData = String.Format(httpRow, fieldName, filename, contentType);
 
            byte[] headerBytes = encoding.GetBytes(httpRowData);
            byte[] endBytes = encoding.GetBytes(end);
            byte[] fileDataBytes = new byte[headerBytes.Length + fileBytes.Length + endBytes.Length];
 
            headerBytes.CopyTo(fileDataBytes, 0);
            fileBytes.CopyTo(fileDataBytes, headerBytes.Length);
            endBytes.CopyTo(fileDataBytes, headerBytes.Length + fileBytes.Length);
 
            bytesArray.Add(fileDataBytes);
        }
        #endregion
    }
}

  private void sendFileData(string sUrl, string pdfPathName, int member_id, string access_token, out string responseText)
        {
            string url = sUrl;//发送到的页面的地址
            string image_path = pdfPathName;//文件的位置
            FileStream fs = new FileStream(image_path, System.IO.FileMode.Open, System.IO.FileAccess.Read);
 
            byte[] fileBytes = new byte[fs.Length];
            fs.Read(fileBytes, 0, fileBytes.Length);
            fs.Close();
            fs.Dispose();
 
            HttpRequestClient httpRequestClient = new HttpRequestClient();
            httpRequestClient.SetFieldValue("member_id", member_id.ToString());//发送数据
            httpRequestClient.SetFieldValue("access_token", access_token);//发送数据
            int pos = image_path.LastIndexOf("\");
            string fileName = image_path.Substring(pos + 1);
            httpRequestClient.SetFieldValue("key", fileName, "application/octet-stream", fileBytes);
            bool uploaded = httpRequestClient.Upload(url, out responseText);

--------------------- 
作者：zhgl7688 
来源：CSDN 
原文：https://blog.csdn.net/zhgl7688/article/details/51593434 
版权声明：本文为博主原创文章，转载请附上博文链接！

     /// <summary>
        /// post发送数据
        /// </summary>
        ///  <param name="url">接收地址</param>
        /// <param name="postString">拼接Post字符串"arg1=a&arg2=b"</param>
        /// <returns></returns>
        public static string HttpUploadData(string url, string postString)
        {
            byte[] postData = Encoding.UTF8.GetBytes(postString);//编码，尤其是汉字，事先要看下抓取网页的编码方式  
            WebClient webClient = new WebClient();
            webClient.Headers.Add("Content-Type", "application/x-www-form-urlencoded");//采取POST方式必须加的header，如果改为GET方式的话就去掉这句话即可  
            byte[] responseData = webClient.UploadData(url, "POST", postData);//得到返回字符流  
            return   Encoding.UTF8.GetString(responseData);//解码 
        }