使用'application/x-www-form-urlencoded'上傳文件

Question

我想用C＃和'application/x-www-form-urlencoded'方法上傳文件。我見過的所有示例都先將文件數據讀入一個字節數組，但這對我來說不起作用，因爲我發送的文件超過了500MB。所以我正在尋找一種直接從磁盤流式傳輸文件的方法。

這個問題的好處是從指定的字節位置讀取文件，例如從第一個字節開始到最後一個，我可以從第500個字節開始到最後一個。

Answer 1

你應該把你的塊寫入數據，因此上傳的主要部分應該像

var buffer = new byte[4096]; 
int bytesRead; 
while ((bytesRead = fileData.Read(buffer, 0, buffer.Length)) != 0) 
    requestStream.Write(buffer, 0, bytesRead); 

所有上傳的代碼。

public static class Upload 
{ 
    private const string FileFieldNameDefault = "fileContent"; 

    public static WebResponse PostFile 
     (Uri requestUri, NameValueCollection postData, Stream fileData, string fileName, 
     string fileContentType, string fileFieldName, CookieContainer cookies, 
     NameValueCollection headers) 
    { 
     ServicePointManager.Expect100Continue = false; 

     if (requestUri.Scheme == "https") 
     { 
      ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3; 

      ServicePointManager.ServerCertificateValidationCallback += (sender, cert, chain, err) => true; 
     } 

     var webRequest = (HttpWebRequest)WebRequest.Create(requestUri); 

     webRequest.Method = "POST"; 

     string boundary = "----------" + DateTime.Now.Ticks.ToString("x", CultureInfo.InvariantCulture); 

     webRequest.ContentType = "multipart/form-data; boundary=" + boundary; 

     string ctype; 

     if (string.IsNullOrEmpty(fileContentType)) 
      fileContentType = TryGetContentType(fileName, out ctype) 
           ? ctype 
           : "application/octet-stream"; 

     fileFieldName = string.IsNullOrEmpty(fileFieldName) ? FileFieldNameDefault : fileFieldName; 

     if (headers != null) 
      foreach (string key in headers.AllKeys) 
      { 
       var values = headers.GetValues(key); 
       if (values != null) 
        foreach (var value in values) 
         webRequest.Headers.Add(key, value); 
      } 

     if (cookies != null) 
      webRequest.CookieContainer = cookies; 

     var sbHeader = new StringBuilder(); 

     if (fileData != null) 
     { 
      var fileNameValue = string.Empty; 

      if (string.IsNullOrEmpty(fileName) == false) 
       fileNameValue = string.Format(CultureInfo.InvariantCulture, "filename=\"{0}\"", Path.GetFileName(fileName)); 

      sbHeader 
       .AppendFormat("--{0}", boundary) 
       .AppendLine() 
       .AppendFormat("Content-Disposition: form-data; name=\"{0}\"; {1}", fileFieldName, fileNameValue) 
       .AppendLine() 
       .AppendFormat("Content-Type: {0}", fileContentType) 
       .AppendLine() 
       .AppendLine(); 
     } 

     var sbFooter = new StringBuilder(); 
     sbFooter.AppendLine(); 

     if (postData != null) 
      foreach (var key in postData.AllKeys) 
      { 
       var values = postData.GetValues(key); 
       if (values != null) 
        foreach (var value in values) 
         sbFooter 
          .AppendFormat("--{0}", boundary) 
          .AppendLine() 
          .AppendFormat("Content-Disposition: form-data; name=\"{0}\"", key) 
          .AppendLine() 
          .AppendLine() 
          .Append(value) 
          .AppendLine(); 
      } 

     sbFooter.AppendFormat("--{0}--\r\n", boundary); 

     byte[] header = Encoding.UTF8.GetBytes(sbHeader.ToString()); 
     byte[] footer = Encoding.UTF8.GetBytes(sbFooter.ToString()); 
     long contentLength = header.Length + (fileData != null ? fileData.Length : 0) + footer.Length; 

     webRequest.ContentLength = contentLength; 

     using (var requestStream = webRequest.GetRequestStream()) 
     { 
      requestStream.Write(header, 0, header.Length); 

      if (fileData != null) 
      { 
       var buffer = new byte[4096]; 
       int bytesRead; 
       while ((bytesRead = fileData.Read(buffer, 0, buffer.Length)) != 0) 
        requestStream.Write(buffer, 0, bytesRead); 
      } 

      requestStream.Write(footer, 0, footer.Length); 

      return webRequest.GetResponse(); 
     } 
    } 

    public static WebResponse PostFile 
     (Uri requestUri, NameValueCollection postData, string fileName, 
     string fileContentType, string fileFieldName, CookieContainer cookies, 
     NameValueCollection headers) 
    { 
     using (var fileData = File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)) 
      return PostFile(requestUri, postData, fileData, 
          fileName, fileContentType, fileFieldName, cookies, 
          headers); 
    } 

    private static bool TryGetContentType(string fileName, out string contentType) 
    { 
     try 
     { 
      RegistryKey key = Registry.ClassesRoot.OpenSubKey(@"MIME\Database\Content Type"); 

      if (key != null) 
      { 
       foreach (string keyName in from keyName in key.GetSubKeyNames() 
              let subKey = key.OpenSubKey(keyName) 
              where subKey != null 
              let subKeyValue = (string)subKey.GetValue("Extension") 
              where string.IsNullOrEmpty(subKeyValue) == false 
              where string.Compare(Path.GetExtension(fileName), subKeyValue, StringComparison.OrdinalIgnoreCase) == 0 
              select keyName) 
       { 
        contentType = keyName; 
        return true; 
       } 
      } 
     } 
     catch 
     { 
      // fail silently 
      // TODO: rethrow registry access denied errors 
     } 
     contentType = string.Empty; 
     return false; 
    } 
}