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c# 爬虫（三）文件上传

yunbo1
windos
2026-06-22
152

在上一篇中，我们说了模拟登录，

下面我们说说附件上传。

据说，最早的http协议是不支持附件上传的，后来有添加了一个RFC 2045 协议，才支持附件上传，关于附件上传，请参见

http://www.cnblogs.com/greenerycn/archive/2010/05/15/csharp_http_post.html

好了，其实用C#模拟上传附件，主要的难点就在于如何构建此协议的格式以及编码。

作为备忘，我这里只放一段成品代码了。

参数：URL,上传控件的id，附件的本地全路径，传输的Key-value数据

 
          public 
          string 
          HttpWebUpload(
          string 
          url, 
          string 
          fileControlID, 
          string 
          fileFullPath, Dictionary<
          string
          , 
          string
          > dic)
         
          {
         
          string 
          fileContentType = 
          "application/octet-stream"
          ;
          //"application/octet-stream";//"text/plain";//image/jpeg
         
          int 
          index = fileFullPath.LastIndexOf(
          ‘\\‘
          );
         
          string 
          filename = fileFullPath.Substring(index+1);
         
          var 
          boundary = DateTime.Now.Ticks.ToString(
          "x"
          );
         
          var 
          beginBoundary = 
          "--" 
          + boundary;
         
          var 
          reqContentType = 
          "multipart/form-data; boundary=" 
          + boundary;
         
          var 
          memStream = 
          new 
          MemoryStream();
         
          var 
          fileStream = 
          new 
          FileStream(fileFullPath, FileMode.Open, FileAccess.Read);
         
          int 
          fsLen = (
          int
          )fileStream.Length;
         
          byte
          [] btfileValue = 
          new 
          byte
          [fsLen];
         
          int 
          r = fileStream.Read(btfileValue, 0, btfileValue.Length);
         
          StringBuilder fileHeader = 
          new 
          StringBuilder();
         
          fileHeader.AppendLine(beginBoundary);
         
          fileHeader.AppendLine(
          string
          .Format(
          "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\""
          , fileControlID, filename));
         
          fileHeader.AppendLine(
          string
          .Format(
          "Content-Type: {0}"
          , fileContentType));
         
          fileHeader.AppendLine();
         
          var 
          btfileKey = Encoding.UTF8.GetBytes(fileHeader.ToString());
         
          StringBuilder dicData = 
          new 
          StringBuilder();
         
          dicData.AppendLine();
         
          foreach 
          (
          var 
          item 
          in 
          dic)
         
          {
         
          dicData.AppendLine(beginBoundary);
         
          dicData.AppendLine(
          string
          .Format(
          "Content-Disposition:form-data; name=\"{0}\""
          , item.Key));
         
          dicData.AppendLine();
         
          dicData.AppendLine(item.Value);
         
          }
         
          dicData.AppendLine(beginBoundary + 
          "--"
          );
         
          var 
          btDic = Encoding.UTF8.GetBytes(dicData.ToString());
         
          HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
         
          req.Method = 
          "POST"
          ;
         
          req.AllowAutoRedirect = 
          false
          ;
         
          req.ContentType = reqContentType;
         
          if 
          (!
          string
          .IsNullOrEmpty(UserAgent))
         
          {
         
          req.UserAgent = 
          this
          .UserAgent;
         
          }
         
          if 
          (!
          string
          .IsNullOrEmpty(Cookie))
         
          {
         
          req.CookieContainer = 
          new 
          CookieContainer();
         
          req.CookieContainer.SetCookies(req.RequestUri, 
          this
          .Cookie);
         
          }
         
          req.ContentLength = btfileKey.Length + btfileValue.Length + btDic.Length;
         
          Stream postDataStream = req.GetRequestStream();
         
          postDataStream.Write(btfileKey, 0, btfileKey.Length);
         
          postDataStream.Write(btfileValue, 0, btfileValue.Length);
         
          postDataStream.Write(btDic, 0, btDic.Length);
         
          postDataStream.Close();
         
          HttpWebResponse resp = (HttpWebResponse)req.GetResponse();
         
          string 
          html = 
          new 
          StreamReader(resp.GetResponseStream()).ReadToEnd();
         
          return 
          html;
         
          }

　　注意，这里如果需要cookie,则添加对应的cookie。

调用方法

 
     
      
        
       
          string 
          controlid = 
          "fupCert"
          ;
         

          string 
          filefullPath = 
          "f:\\3.pdf"
          ;
         

          string 
          url = 
          "http://10.35.3.240/NT_HandbookExtend/FrmCertificate.aspx?type=N&zdtype=J&DELEGATENO=SBWJ16100001&ID=SB20161018000001%2c3206960757&Action=Modify&manualRecordID=SL20161018000001&tm=0.17032586549994377"
          ;
         

           
         

          var 
          hiddenVal = web.GetDoNetHiddenValuesByUrl(url);
          //获取__VIEWSTATE，与__EVENTVALIDATION隐藏域值
         

           
         

          Dictionary<
          string
          , 
          string
          > dic = 
          new 
          Dictionary<
          string
          , 
          string
          >();
         

          dic.Add(
          "__EVENTARGUMENT"
          , 
          ""
          );
         

          dic.Add(
          "__EVENTTARGET"
          , 
          "btnUpload"
          );
         

          dic.Add(
          "__EVENTVALIDATION"
          , hiddenVal.Eventvalidation);
         

          dic.Add(
          "__PREVIOUSPAGE"
          , 
          "EncayjCF95BJXxMazWGgd9UdPYeLp64GjuJlZ-rvnQ5n34-y7KQYllE35nAdVFvk0"
          );
         

          dic.Add(
          "__VIEWSTATE"
          , hiddenVal.Vievstate);
         

          dic.Add(
          "__VIEWSTATEENCRYPTED"
          , 
          ""
          );
         

          dic.Add(
          "grdNavigatorPRE_EMS3_CUS_IMG$ctl06"
          , 
          ""
          );
         

          dic.Add(
          "grdNavigatorPRE_EMS3_CUS_IMG$ctl07"
          , 
          "15"
          );
         

          dic.Add(
          "grdNavigatorPRE_EMS3_CUS_IMG$labelRowCount"
          , 
          "8"
          );
         

          dic.Add(
          "hfERP"
          , 
          "http://www.nteport.gov.cn/cerp/platform/erp/documentManagement/documentDocking.jsp"
          );
         

          dic.Add(
          "hidFileType"
          , 
          "333"
          );
         

          dic.Add(
          "hidID"
          , 
          ""
          );
         

          //web.UserAgent = "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)";
         

          string 
          html = web.HttpWebUpload(url, controlid, filefullPath, dic);
         
 
      
 
     
   