Thanks for all the responses. I had (and still do) little
understanding of responses and requests as I rarely work directly with
them. However, I now see that GWT-RPC is not the way to go. From
what I've read and what I saw using Firebug, GWT-RPC sets up the
response variable for it's own purposes as part of GWT-RPC, so by
going in and modifying it myself I caused problems with GWT-RPC.
Instead of extending RemoteServiceServlet, I extended HttpServlet and
have been able to get a result. However, I was not able to get a
result from the GWT app yet using RequestBuilder. I attempted to do
so, and the function ran (I had some print statements which showed up
in the log) successfully and the RequestCallback received a response.
However, nothing happened.
Is it possible to do this using RequestBuilder? Using Firebug, I saw
a response was generated and it seemed to have the correct headers as
I had set. However, no PDF file opened, was offered, etc. and it
appeared as if nothing happened.
I was able to get it to generate a PDF by simply typing the URL into
my browser...
www.site.com/app-name/PDFServlet
that URL displayed a Hello World example PDF as expected. Ideally,
this would open by clicking from GWT app. I suppose I could create a
standard HTML link in the GWT app and that may work, but I wonder why
the RequestBuilder did not work, even though response was returned.
And finally - does anyone have any tips on ways to make it more secure
somehow? While there is a rare chance, and it probably wouldn't be
anything serious, anyone could type in the URL in the browser and view
the reports that will be generated, provided they pass in the report
ID, etc. Is there a way that it would only work if accessed from the
app (which is user protected) or are there any other tips on making it
a bit more secure?
Below is my current servlet code, followed by the RequestBuilder part
of the app that failed to work as expected.
public class PDFServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse
response) throws IOException, ServletException {
System.out.println("Hello World! to follow");
Document document = new Document();
// generate test PDF
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
//PdfWriter.getInstance(document, new FileOutputStream
("HelloWorld.pdf"));
PdfWriter.getInstance(document, baos);
document.open();
document.add(new Paragraph("Hello World!"));
document.close();
// setting some response headers
response.setHeader("Expires", "0");
response.setHeader("Cache-Control", "must-revalidate,
post-check=0,
pre-check=0");
response.setHeader("Pragma", "public");
response.setContentType("application/pdf");
// content length is needed for MSIE
response.setContentLength(baos.size());
// write ByteArrayOutputStream to ServletOutputStream
ServletOutputStream out = response.getOutputStream();
baos.writeTo(out);
out.flush();
}
catch (Exception e) {
System.out.println("PDFServlet::doGet::Exception " +
e.getMessage
());
}
}
}
/*
* Code in GWT app - ultimately I will pass report type, ID to the
servlet to generate the
* appropriate report
*/
public void onRecordClick(RecordClickEvent event) {
//need to add report ID, etc. to the request in
the future
RequestBuilder request = new
RequestBuilder(RequestBuilder.GET,
"PDFService");
request.setCallback(new RequestCallback() {
public void onError(Request request,
Throwable exception) {
SC.say("onError"); // this is
just an alert
}
public void onResponseReceived(Request
request,
Response response) {
SC.say("onResponseReceived");
// alert
}
});
On Apr 6, 5:45 pm, Daniel Jue <teamp...@gmail.com> wrote:
> There is a PDF generation demo using a GWT entrypoint on the DynamicJasper
> website (a wrapper for Jasper, which I think still uses iText deep inside).
>
> http://dynamicjasper.sourceforge.net/
>
> Anyway you can look at the relevant servlet code there, and the hand-off
> from the GWT "run report" button.
>
> On Mon, Apr 6, 2009 at 4:55 PM, thebuz...@gmail.com
> <thebuz...@gmail.com>wrote:
>
>
>
> > For itext just do a like to like a jsp page that will run the itext
> > gen. Thats how i do it and it works great.
>
> > On Apr 6, 11:55 am, Peter Ondruška <peter.ondru...@gmail.com> wrote:
> > > I think you should not use GWT RPC servlet, just use normal servlet.
>
> > > 2009/4/6, Superman859 <russ.d.hollo...@gmail.com>:
>
> > > > I want to use iText to generate a PDF file. Ideally, I can
> > > > incorporate a generatePDF() method into my interface and my Servlet
> > > > that is involved in GWT-RPC. When that method is called, I want it to
> > > > generate a PDF file and either display it to the user in a new window
> > > > or present a save dialog box or anything - something that leaves the
> > > > GWT app as it was and allows the user to view / save / print the PDF.
>
> > > > Generating the PDF is not a problem. I can generate one and write it
> > > > to a file on the server without any trouble. However, I am having
> > > > trouble presenting the user with it (I would rather NOT write them to
> > > > files on the server, and just let the user save on their own machine
> > > > if they wish to do so).
>
> > > > Here is code for a sample "Hello World"
>
> > > > public boolean generatePDF(ReportDO report, int id) {
> > > > System.out.println("hello world to follow");
> > > > // get request
> > > > //HttpServletRequest request = getThreadLocalRequest();
>
> > > > // get response
> > > > HttpServletResponse response = getThreadLocalResponse();
>
> > > > Document document = new Document();
>
> > > > // generate test PDF
> > > > try {
>
> > > > ByteArrayOutputStream baos = new ByteArrayOutputStream();
> > > > //PdfWriter.getInstance(document, new FileOutputStream
> > > > ("HelloWorld.pdf"));
> > > > PdfWriter.getInstance(document, baos);
> > > > document.open();
> > > > document.add(new Paragraph("hello world"));
> > > > document.close();
>
> > > > // setting some response headers
> > > > response.setHeader("Expires", "0");
> > > > response.setHeader("Cache-Control", "must-revalidate,
> > post-check=0,
> > > > pre-check=0");
> > > > response.setHeader("Pragma", "public");
>
> > > > response.setContentType("application/pdf");
>
> > > > // content length is needed for MSIE
> > > > response.setContentLength(baos.size());
>
> > > > // write ByteArrayOutputStream to ServletOutputStream
> > > > ServletOutputStream out = response.getOutputStream();
> > > > baos.writeTo(out);
> > > > out.flush();
> > > > }
> > > > catch (Exception e) {
> > > > System.out.println("generatePDF:Exception " +
> > e.getMessage());
> > > > }
>
> > > > return true;
> > > > }
>
> > > > This code is in my GWT-RPC Servlet, which extends
> > > > RemoteServiceServlet. Note if I use the currently commented line of
> > > > FileOutputStream("HelloWorld.pdf") it will generate the file and work
> > > > fine. However, if I try to send it to the browser, nothing appears,
> > > > and the AsyncCallback for GWT-RPC calls the onFailure() method.
>
> > > > Does anyone know where the problem might be? I'm assuming it has to
> > > > do with response. RemoteServiceServlet has a method
> > > > getThreadLocalResponse() which returns HttpServletResponse, which is
> > > > what the iText examples use. I know very little about these response
> > > > objects. But it seems that somehow there is some interference between
> > > > that and GWT-RPC. The AsyncCallback is a success when writing to
> > > > file. However, when attempting to send to browser, it fails.
>
>
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