/// <summary>
/// Http上传文件
/// </summary>
public static string HttpUploadFile(string url, string path)
{// 设置参数HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;CookieContainer cookieContainer = new CookieContainer();request.CookieContainer = cookieContainer;request.AllowAutoRedirect = true;request.Method = "POST";string boundary = DateTime.Now.Ticks.ToString("X"); // 随机分隔线request.ContentType = "multipart/form-data;charset=utf-8;boundary=" + boundary;byte[] itemBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");byte[] endBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");int pos = path.LastIndexOf("\\");string fileName = path.Substring(pos + 1);//请求头部信息 StringBuilder sbHeader = new StringBuilder(string.Format("Content-Disposition:form-data;name=\"file\";filename=\"{0}\"\r\nContent-Type:application/octet-stream\r\n\r\n", fileName));byte[] postHeaderBytes = Encoding.UTF8.GetBytes(sbHeader.ToString());FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);byte[] bArr = new byte[fs.Length];fs.Read(bArr, 0, bArr.Length);fs.Close();Stream postStream = request.GetRequestStream();postStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);postStream.Write(postHeaderBytes, 0, postHeaderBytes.Length);postStream.Write(bArr, 0, bArr.Length);postStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length);postStream.Close();//发送请求并获取相应回应数据HttpWebResponse response = request.GetResponse() as HttpWebResponse;//直到request.GetResponse()程序才开始向目标网页发送Post请求Stream instream = response.GetResponseStream();StreamReader sr = new StreamReader(instream, Encoding.UTF8);//返回结果网页（html）代码string content = sr.ReadToEnd();return content;}

接收文件代码

using System;
using System.Web;
namespace SWX
{public partial class test2 : System.Web.UI.Page{protected void Page_Load(object sender, EventArgs e){HttpPostedFile file = Request.Files[0];file.SaveAs(MapPath("\\UploadFile\\" + file.FileName));Response.Write("Success\r\n");}}
}

其他参考连接

C#HTTP文件上传和参数_c# http上传文件-CSDN博客