While
developing ASP.NET site, its common feature to allow download of a file.
Along
with download large file, site should allow user to do other tasks on the page
i.e. allow user to download file async.
Here
are the guidelines for doing it
- Create two web page - default.aspx and
Download.aspx
- On default.aspx take one hidden frame
and button to download as below
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1"
runat="server">
<title></title>
<script type="text/javascript" language="javascript">
function
DownLoadFile(uid) {
var
iframe = document.getElementById("ifrmDownloadframe");
iframe.src = uid;
return
false;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<iframe style="display: none" id="ifrmDownloadframe"></iframe>
<div>
Current Date Time is <asp:Label ID="Label1" runat="server"
></asp:Label>
<br />
<asp:Button ID="btnDateTime" runat="server" Text="Show Date Time"
onclick="btnDateTime_Click" />
<asp:Button ID="btnDownload" runat="server" Text="Download" />
</div>
</form>
</body>
</html>
- Set Download.aspx page with required
query string as a frame source as below from default.aspx
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object
sender, EventArgs e)
{
if
(!Page.IsPostBack)
{
Label1.Text = DateTime.Now.ToString();
btnDownload.Attributes.Add("onclick", DownloadShippedFile(100));
}
}
protected void btnDateTime_Click(object
sender, EventArgs e)
{
Label1.Text = DateTime.Now.ToString();
}
private string DownloadShippedFile(int
Id)
{
string
result = string.Empty;
try
{
string
key = string.Format("Type=DownloadEmpFile&EmployeeId={0}",
Id);
string
strURL = Request.ApplicationPath + "/Download.aspx?"
+ key;
result = "return
DownLoadFile('" + strURL + "');";
}
catch (Exception ex)
{
result = string.Format("alert('{0}');return false;",
ex.Message);
}
return
result;
}
}
- On Download.aspx, get filepath from
query string and force file to download on browser
protected void Page_Load(object
sender, EventArgs e)
{
if
(Request.QueryString.Count > 0 && Request.QueryString["EmployeeId"] != null)
{
//Based
upon id get file name from database or from some where else. I am considering
direct file name
string
filePathFromDatabase = @"\\xyz\abc.zip";
DownloadFile(filePathFromDatabase);
}
}
private void DownloadFile(string
sFileName)
{
FileStream
fileStream = new FileStream(sFileName,
FileMode.Open, FileAccess.Read);
byte[]
buffer = new byte[(int)fileStream.Length];
fileStream.Read(buffer, 0, (int)fileStream.Length);
fileStream.Close();
Response.Clear();
Response.ClearContent();
Response.ClearHeaders();
if
(sFileName.EndsWith(".html"))
Response.ContentType = "text/html";
else
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Length",
buffer.Length.ToString());
Response.AddHeader("Content-Disposition", "attachment;filename=\"" +
sFileName + "\"");
Response.BinaryWrite(buffer);
Response.Flush();
Response.End();
}
Please leave your comments if it is useful for you.
