Download large file from URL in .net core web api

Question

In .net framework 4.7, I was able to use this logic to stream file from another URL (in Chunks), but in .net core System.Web.HttpContext and HttpResponse are not available. Any help pls, to achieve this objective of downloading in chunks from another URL, in .net core 3.1. The HttpContext.Current.Response , IsClientConnected etc are not available in .net core,

//Create a stream for the file
Stream stream = null;

//chunk of bytes to read at a time and send to the client 
int bytesToRead = 10000;

// Buffer to read bytes in chunk size specified above
byte[] buffer = new Byte[bytesToRead];

// The number of bytes read
try
{
  //Create a WebRequest to get the file
  HttpWebRequest fileReq = (HttpWebRequest) HttpWebRequest.Create(url);

  //Create a response for this request
  HttpWebResponse fileResp = (HttpWebResponse) fileReq.GetResponse();

  if (fileReq.ContentLength > 0)
    fileResp.ContentLength = fileReq.ContentLength;

    //Get the Stream returned from the response
    stream = fileResp.GetResponseStream();

    // prepare the response to the client. resp is the client Response
    var resp = HttpContext.Current.Response;

    //Indicate the type of data being sent
    resp.ContentType = "application/octet-stream";

    //Name the file 
    resp.AddHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
    resp.AddHeader("Content-Length", fileResp.ContentLength.ToString());

    int length;
    do
    {
        // Verify that the client is connected.
        if (resp.IsClientConnected)
        {
            // Read data into the buffer.
            length = stream.Read(buffer, 0, bytesToRead);

            // and write it out to the response's output stream
            resp.OutputStream.Write(buffer, 0, length);

            // Flush the data
            resp.Flush();

            //Clear the buffer
            buffer = new Byte[bytesToRead];
        }
        else
        {
            // cancel the download if client has disconnected
            length = -1;
        }
    } while (length > 0); //Repeat until no data is read
}
finally
{
    if (stream != null)
    {           
        stream.Close();
    }
}

There is a same question here, you can refer to this.

mj1313
– mj1313

2020-06-22 08:17:53 +00:00
Commented Jun 22, 2020 at 8:17 — mj1313
– mj1313, Commented Jun 22, 2020 at 8:17

user1066231 · Accepted Answer · 2020-06-22 10:38:10Z

IHttpContextAccessor provides access to context and use the implementation. Thanks to @mj1313 for pointing out the answer in this forum., Link

public class HomeController : Controller
{
    private readonly IHttpContextAccessor _httpContextAccessor;

    public HomeController(IHttpContextAccessor httpContextAccessor)
    {
        _httpContextAccessor = httpContextAccessor;
    }
 

    public async Task<IActionResult> Contact()
    {
       ..

       var resp = _httpContextAccessor.HttpContext.Response;
       resp.Headers.Add("Content-Type", "text/event-stream");

       // Verify that the client is connected.
       if (HttpContext.RequestAborted.IsCancellationRequested == false)
            {
                ..                   
                await resp.Body.WriteAsync(buffer, 0, length); 
                //or await resp.WriteAsync("hello"); 
                               
                resp.Body.Flush();

                ..
            }
       ..
    
    }
}

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