IllegalStateException Response has already been committed

[raju svgk]

Hi,
I am using HttpServletResponse and ServletOutputStream. The code is as follows:

protected void onRunReport (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
PrintWriter out = null;
ServletOutputStream os = null;
long reportid;
try {
reportid = Integer.parseInt(request.getParameter("rqname"));
String reportname = QReportSession.getReportName(reportid);
byte[] reportbyte = QReportSession.runReport(reportid);
response.setContentType("application/x-download");
response.setHeader("Content-Disposition", "attachment; filename=" + reportname + ".pdf");
response.setContentLength(reportbyte.length);
os = response.getOutputStream();
os.write(reportbyte);
os.flush();
os.close();
System.out.println (os);
os = null;
response.sendRedirect("qtweb.qtReportServ?command=options");
} catch (qRemoteException rex) {
rex.printStackTrace();
if (os != null) {
os.close();
}
out = response.getWriter();
qtMainServ.errorPage (out, "Run Report Failed: " + rex.getMessage());
} catch (IllegalStateException ise) {
ise.printStackTrace();
if (os != null) {
os.close();
}
out = response.getWriter();
qtMainServ.errorPage (out, "Run Report Failed: " + ise.getMessage());
} catch (NumberFormatException nfe) {
nfe.printStackTrace();
if (os != null) {
os.close();
}
out = response.getWriter();
qtMainServ.errorPage (out, "Run Report Failed: " + nfe.getMessage());
} catch (NullPointerException npe) {
if (os != null) {
os.close();
}
npe.printStackTrace();
out = response.getWriter();
qtMainServ.errorPage (out, "Run Report Failed: " + npe.getMessage());
} catch (Exception ex) {
ex.printStackTrace();
if (os != null) {
os.close();
}
out = response.getWriter();
qtMainServ.errorPage (out, "Run Report Failed: " + ex.getMessage());
}
}

Actually when I click "Run Report" button in a html form, this method will be invoked. The actual requirement is after I click the "Run Report", .pdf should get downloaded and goto a different page. To achieve this I used response.sendRedirect() method. I got the following error:
java.lang.IllegalStateException: Response has already been committed, be sure not to write to the OutputStream or to trigger a commit due to any other action before calling this method.
Is there a way to redirect from a page to another when I used response.getOutputStream().
Also, if any errors occured, how do I show it. Actually in my code I am trying to get Writer object to show error messages. This will not work. Any ideas how to show error messages when response.getOutputStream() is used.
regds
-raju

[David Hibbs]

java.lang.IllegalStateException: Response has already been committed, be sure not to write to the OutputStream or to trigger a commit due to any other action before calling this method.

The error message says it all...

Is there a way to redirect from a page to another when I used response.getOutputStream().

No. You've started writing a response; telling a browser to go somewhere else in the middle of it is a completely different response.
The answer to your problem is either to redirect the user to the file or to write the entire file back to the output stream yourself.

Also, if any errors occured, how do I show it. Actually in my code I am trying to get Writer object to show error messages. This will not work. Any ideas how to show error messages when response.getOutputStream() is used.

It's much more elegant from both the developers' and users' viewpoints to redirect to an error page and write the errors to a log. You can either forward or redirect the request/response using the RequestDispatcher.