使用 httpwebrequest 和 cookie 下载的 c# 文件被损坏

Question

我正在尝试制作一个程序，该程序能够使用 httpwebrequest 和 cookie（用于保持登录状态的凭据信息）使用 URI(URL) 下载文件。

我可以使用以下代码下载文件，但文件在下载后损坏。

当我将 xlsx 文件（在网页上）下载到本地驱动器的文本文件中时，我在损坏的文件中看到原始文件中的部分数字和文字，因此我认为我已经找到了正确的文件.

然而，当我在本地驱动器的 xlsx 文件中下载 xlsx 文件（在网页上）时，它似乎无法打开说

excel cannot open the file 'filename.xlsx' because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file.

有什么方法可以在下载后保留完整的原始文件内容？

我也附上一部分结果内容

private void btsDownload_Click(object sender, EventArgs e)
{
  try
  {
    string filepath1 = @"PathAndNameofFile.txt";                     
    string sTmpCookieString = GetGlobalCookies(webBrowser1.Url.AbsoluteUri);            
    HttpWebRequest fstRequest = (HttpWebRequest)WebRequest.Create(sLinkDwPage);
    fstRequest.Method = "GET";                                                          
    fstRequest.CookieContainer = new System.Net.CookieContainer();                      
    fstRequest.CookieContainer.SetCookies(webBrowser1.Document.Url, sTmpCookieString);
    HttpWebResponse fstResponse = (HttpWebResponse)fstRequest.GetResponse();            
    StreamReader sr = new StreamReader(fstResponse.GetResponseStream());                
    string sPageData = sr.ReadToEnd();                                                  
    sr.Close();                                                                         

    string sViewState = ExtractInputHidden(sPageData, "__VIEWSTATE");                   
    string sEventValidation = this.ExtractInputHidden(sPageData, "__EVENTVALIDATION");  

    string sUrl = ssItemLinkDwPage;                                                  
    HttpWebRequest hwrRequest = (HttpWebRequest)WebRequest.Create(sUrl);
    hwrRequest.Method = "POST";                                                         

    string sPostData = "__EVENTTARGET=&__EVENTARGUMENT=&__VIEWSTATE=" + sViewState + "&__EVENTVALIDATION=" + sEventValidation + "&Name=test" + "&Button1=Button";


    ASCIIEncoding encoding = new ASCIIEncoding();
    byte[] bByteArray = encoding.GetBytes(sPostData);
    hwrRequest.ContentType = "application/x-www-form-urlencoded";

    Uri convertedURI = new Uri(ssDwPage);
    hwrRequest.CookieContainer = new System.Net.CookieContainer();
    hwrRequest.CookieContainer.SetCookies(convertedURI, sTmpCookieString);

    hwrRequest.ContentLength = bByteArray.Length;
    Stream sDataStream = hwrRequest.GetRequestStream();
    sDataStream.Write(bByteArray, 0, bByteArray.Length);
    sDataStream.Close();
    using (WebResponse response = hwrRequest.GetResponse())
    {
      using (sDataStream = response.GetResponseStream())
      {
        StreamReader reader = new StreamReader(sDataStream);
        {
          string sResponseFromServer = reader.ReadToEnd();
          FileStream fs = File.Open(filepath1, FileMode.OpenOrCreate, FileAccess.Write);

          Byte[] info = encoding.GetBytes(sResponseFromServer);

          fs.Write(info, 0, info.Length);
          fs.Close();

          reader.Close();
          sDataStream.Close();
          response.Close();
        }
      }
    }
  }
  catch
  {
    MessageBox.Show("Error");
  }
}

Answer 1

StreamReader 用于处理 text 数据。使用它会破坏您的 二进制数据（excel 文件）.

直接将sDataStream写入文件。对于前。

sDataStream.CopyTo(fs)

PS：我准备了一个测试用例（使用类似的逻辑）来展示你的代码如何不工作

var binaryData = new byte[] { 128,255 };
var sr = new StreamReader(new MemoryStream(binaryData));
var str3 = sr.ReadToEnd();
var newData = new ASCIIEncoding().GetBytes(str3); //<-- 63,63

只需比较 binaryData 与 newData

使用 httpwebrequest 和 cookie 下载的 c# 文件被损坏

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