如何正确地通过rest服务传递流以检索其长度

Question

我正从这条小溪经过：

StreamReader sr = new StreamReader(openFileDialog1.FileName);
byte[] fileStream = Utility.ReadFully(sr.BaseStream);
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(baseAddress));
request.Method = "POST";
request.ContentType = "application/octet-stream";

Stream serverStream = request.GetRequestStream();
serverStream.Write(fileStream, 0, fileStream.Length);
serverStream.Close();

HttpWebResponse response2 = (HttpWebResponse)request.GetResponse();
if (response2.StatusCode == HttpStatusCode.OK)
{
    MessageBox.Show(Utility.ReadResponse(response2));
}  

-------------------------------------------------------------------------

public static byte[] ReadFully(Stream input)
{
    byte[] buffer = new byte[16 * 1024];
    using (MemoryStream ms = new MemoryStream())
    {
        if (input != null)
        {
            int read;
            while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
            {
                ms.Write(buffer, 0, read);
            }
        }
        return ms.ToArray();
    }
}  

然后在服务器上处理它：

public bool UploadPhotoStream(string someStringParam, Stream fileData)
{
    string filePath = string.Format("{0}/{1}", 'sdfgsdf87s7df8sd', '24asd54s4454d5f4g');

    ProductPhoto newphoto = new ProductPhoto();
    newphoto.FileSizeBytes = fileData.Length / 1024 / 1024;
    newphoto.FileLocation = filePath;

    ...
}  

现在，当我打电话给NotSupportedException时，我得到了fileData.Length。我知道这是因为溪流关闭了。但我怎么能重新打开它呢？或者，当我将流传递给服务时，我应该如何做才能得到它的长度？

Answer 1

为什么不传递内容长度的标题呢？您的服务器可以检查标题，并确切地知道要发送的内容有多少字节。如何读取标题取决于您所使用的http框架、ASP.NET Web、经典的WCF、HttpListener等等。

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(baseAddress));
request.Method = "POST";
request.ContentType = "application/octet-stream";
request.ContentLength = new FileInfo(openFileDialog1.FileName).Length

如果没有内容长度标头，http服务器就永远不可能知道要读取的字节数。它所知道的是有一个流，并将阅读它，直到没有更多的数据。这也是浏览器在下载某些内容时可以显示进度条的方式。它需要bytesDownloaded /内容长度。

根据这篇文章：https://stackoverflow.com/a/8239268/1160036

您可以像这样从web方法中访问标题。

long dataLength = long.Parse(HttpContext.Current.Request.Headers["Content-Length"]);