获取href上的请求状态

Question

I am using a href link to download a file from the server. I want to do some activity after the file downloaded completely from server. Like XMLHTTP, can i set some call back function on href which will be called on completion of the request.

My code is like this

///link to download report
<div class='report-download'><a href='' id='downloadreq'></a></div>
$("#report-download").click(OnClick);

 ///onlick function
functon OnClick()
{
  ///start progress bar
  $("#downloadreq").attr("href","8001.html?data=dowloadreport");
  //stop progress bar

}

I want to show a progress bar while download happening and I have code to start and stop the progress bar window .But When i insert code to stop the Progress bar, its getting executed before actual download completed and the progress bar get disappeared. How will i identify the report download is completed (or) is it possible to identify that the download is completed. The time taken for report download will very depend on number of record to download. So i cant wait for a default time period and stop the progress bar.

Answer 1

I think there is a no way like event to know if a file download has been already finished or not. If I were you, I would do something like this:

1. Open the file via PHP and send it to the client's browser via HTTP
2. I would have a variable like $_SESSION['lock'] = true; and will set it before start sending the stream to the output
3. When the file download got finished, I would unlock the variable by $_SESSION['lock'] = false;
4. During the file download, I could check the lock value to see if the file has been finished or not. Let say each 2-5 seconds via AJAX.
5. When it's finished - lock is false , I can do whatever needed, but I have no idea how to show the progress bar, even approximately.

Note that if you don't use something like a $_SESSION , the lock mechanism would not works at all, because the script would run each time as a fresh one, without having any idea of the recent variables, etc.

Update:

You may want to use $_SESSION['finished'] instead of $_SESSION['lock'] which would makes more sense, in terms of understanding the source code.