/// <summary>
/// Send the download file to the client.
/// </summary>
/// <param name="httpResponse"></param>
/// <param name="responseHeader"></param>
/// <param name="fileStream"></param>
private static void SendDownloadFile(HttpResponse httpResponse, HttpResponseHeader responseHeader, Stream fileStream)
{
if (httpResponse == null || responseHeader == null)
{
return;
}
if (!string.IsNullOrEmpty(responseHeader.ContentRange))
{
httpResponse.StatusCode = 206;
// Set the start position of the reading files.
string[] range = responseHeader.ContentRange.Split(new char[] { ' ', '=', '-' });
fileStream.Position = Convert.ToInt64(range[2]);
}
httpResponse.Clear();
httpResponse.Buffer = false;
httpResponse.AppendHeader("Accept-Ranges", responseHeader.AcceptRanges);
httpResponse.AppendHeader("Connection", responseHeader.Connection);
httpResponse.AppendHeader("Content-Disposition", responseHeader.ContentDisposition);
httpResponse.ContentEncoding = responseHeader.ContentEncoding;
httpResponse.AppendHeader("Content-Length", responseHeader.ContentLength);
if (!string.IsNullOrEmpty(responseHeader.ContentRange))
{
httpResponse.AppendHeader("Content-Range", responseHeader.ContentRange);
}
httpResponse.ContentType = responseHeader.ContentType;
httpResponse.AppendHeader("Etag", "\"" + responseHeader.Etag + "\"");
httpResponse.AppendHeader("Last-Modified", responseHeader.LastModified);
Byte[] buffer = new Byte[10240];
long fileLength = Convert.ToInt64(responseHeader.ContentLength);
// Send file to client.
while (fileLength > 0)
{
if (httpResponse.IsClientConnected)
{
int length = fileStream.Read(buffer, 0, 10240);
httpResponse.OutputStream.Write(buffer, 0, length);
httpResponse.Flush();
fileLength = fileLength - length;
}
else
{
fileLength = -1;
}
}
}
public static void DownloadFile(HttpContext httpContext, string filePath)
{
if (!IsFileExists(filePath))
{
httpContext.Response.StatusCode = 404;
return;
}
FileInfo fileInfo = new FileInfo(filePath);
if (fileInfo.Length > Int32.MaxValue)
{
httpContext.Response.StatusCode = 413;
return;
}
// Get the response header information by the http request.
HttpResponseHeader responseHeader = GetResponseHeader(httpContext.Request, fileInfo);
if (responseHeader == null)
{
return;
}
FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
try
{
SendDownloadFile(httpContext.Response, responseHeader, fileStream);
}
catch (HttpException ex)
{
httpContext.Response.StatusCode = ex.GetHttpCode();
}
finally
{
fileStream.Close();
}
}
/// <summary>
/// Get the response header by the http request.
/// </summary>
/// <param name="httpRequest"></param>
/// <param name="fileInfo"></param>
/// <returns></returns>
private static HttpResponseHeader GetResponseHeader(HttpRequest httpRequest, FileInfo fileInfo)
{
if (httpRequest == null)
{
return(null);
}
if (fileInfo == null)
{
return(null);
}
long startPosition = 0;
string contentRange = "";
string fileName = fileInfo.Name;
long fileLength = fileInfo.Length;
string lastUpdateTimeStr = fileInfo.LastWriteTimeUtc.ToString();
string eTag = HttpUtility.UrlEncode(fileName, Encoding.UTF8) + " " + lastUpdateTimeStr;
string contentDisposition = "attachment;filename=" + HttpUtility.UrlEncode(fileName, Encoding.UTF8).Replace("+", "%20");
if (httpRequest.Headers["Range"] != null)
{
string[] range = httpRequest.Headers["Range"].Split(new char[] { '=', '-' });
startPosition = Convert.ToInt64(range[1]);
if (startPosition < 0 || startPosition >= fileLength)
{
return(null);
}
}
if (httpRequest.Headers["If-Range"] != null)
{
if (httpRequest.Headers["If-Range"].Replace("\"", "") != eTag)
{
startPosition = 0;
}
}
string contentLength = (fileLength - startPosition).ToString();
if (startPosition > 0)
{
contentRange = string.Format(" bytes {0}-{1}/{2}", startPosition, fileLength - 1, fileLength);
}
HttpResponseHeader responseHeader = new HttpResponseHeader();
responseHeader.AcceptRanges = "bytes";
responseHeader.Connection = "Keep-Alive";
responseHeader.ContentDisposition = contentDisposition;
responseHeader.ContentEncoding = Encoding.UTF8;
responseHeader.ContentLength = contentLength;
responseHeader.ContentRange = contentRange;
responseHeader.ContentType = "application/octet-stream";
responseHeader.Etag = eTag;
responseHeader.LastModified = lastUpdateTimeStr;
return(responseHeader);
}
