I see. You only have trouble if SlideShow creates the original PPT.
I suggest that you always start with an empty template PPT created by
PowerPoint and then add and save.
private static final String EMPTY_FILE = "empty.ppt";
public static SlideShow createPpt(String fileName) throws
IOException {
//retrieve or create the presentation
SlideShow ppt = null;
File file = new File(fileName);
if(file.exists()) {
ppt = new SlideShow(new FileInputStream(file));
} else {
ppt = new SlideShow(new FileInputStream(EMPTY_FILE));
}
return ppt;
}
How does that do?
Regards,
Dave
On Jan 21, 2010, at 3:59 PM, Joe Dente wrote:
The suggestion to re-open the slideshow after every save was made
earlier. I attempted to do that in the prototype (and actually my
project's code does re-open the file every time) and it had no effect.
The problem still occurred. The way I am re-opening a file is
basically
instantiating a new SlideShow around a new File pointing to the same
path every time the program executes. Basically modify the code in the
prototype so that it looks like:
//build the corrupt ppt
System.out.print("Generating three slide ppt...");
//create slide1
SlideShow pptFail = createPpt(FILE_NAME_FAIL);
pptFail.createSlide();
savePpt(FILE_NAME_FAIL, pptFail);
//create slide2
pptFail = createPpt(FILE_NAME_FAIL);
pptFail.createSlide();
savePpt(FILE_NAME_FAIL, pptFail);
//create slide3
pptFail = createPpt(FILE_NAME_FAIL);
pptFail.createSlide();
savePpt(FILE_NAME_FAIL, pptFail);
System.out.println("COMPLETE");
Is there something I need to do to release the previous SlideShow
before
I can re-open? For example, do I need to do anything with the
FileInputStream or File handles that I used to construct the SlideShow
(I assumed the stream would be closed after the SlideShow
construction)?
Thanks,
Joe
-----Original Message-----
From: David Fisher [mailto:[email protected]]
Sent: Thursday, January 21, 2010 4:17 PM
To: POI Users List
Subject: Re: 3rd PowerPoint Slide is Corrupt
Joe,
The workaround for your use case is to re-open the SlideShow after
every save.
According to comments I have seen in the past saving does things to
the SLideShow such that it not really safe to do multiple times.
Regards,
Dave
On Jan 21, 2010, at 1:25 PM, Joe Dente wrote:
A bug has been filed
(https://issues.apache.org/bugzilla/show_bug.cgi?id=48593).
As explained, saving after every slide is created was done simply to
demonstrate the bug. If I delay the save until all 3 slides are
created,
the problem does not exist. However, this is not an option. The
action
is there for the user to generate a new PowerPoint slide. So we
create
the slide and then we need to save it because the user probably
wants to
go look at his new slide. This workflow is fine up until the 3rd
slide,
which is suddenly corrupt.
I appreciate all of your help. Hopefully it's an easy fix or maybe
somebody else out there sees a problem with my sample code.
Thanks,
Joe
-----Original Message-----
From: David Fisher [mailto:[email protected]]
Sent: Thursday, January 21, 2010 1:42 PM
To: POI Users List
Subject: Re: 3rd PowerPoint Slide is Corrupt
Joe -
Don't save after every slide.
//build the corrupt ppt
System.out.print("Generating three slide ppt...");
SlideShow pptFail = createPpt(FILE_NAME_FAIL);
//create slide1
pptFail.createSlide();
//create slide2
pptFail.createSlide();
//create slide3
pptFail.createSlide();
savePpt(FILE_NAME_FAIL, pptFail);
See if that helps.
If not then do what Yegor says, create a Bugzilla and he will look
into it when he has time.
Regards,
Dave
On Jan 21, 2010, at 11:14 AM, Joe Dente wrote:
Thanks for the response.
I find it very hard to believe that nobody's come across this issue
before, so I'm sure I am just doing something wrong such as not
releasing or closing an object or something. Here's a small java app
that demonstrates the problem. I've tried it with POI-3.2-FINAL (the
version I was intending to use) as well as POI-3.6 and the problem
exists in both versions. The main will generate two ppt
presentations;
the 'twoSlides.ppt' deck is valid and the 'threeSlides.ppt' deck
will be
corrupt when you try and open them in PowerPoint. One interesting
thing
to note is that if you generate 3 slides and then do a single save
as
opposed to saving after creating every slide, the slide deck is not
corrupted. In our application, every time the user presses a button
we
export his current context to a PowerPoint slide, which means we
need to
save the slide deck every time the user presses the button. The user
can
press that button as many times as he wants to generate as many
slides
as he wants in a session, and so I'm not sure what exactly to do
about
this problem as far as our app is concerned.
Thanks for the help.
Joe
public class PoiPrototype {
private static final String FILE_NAME_PASS = "twoSlides.ppt";
private static final String FILE_NAME_FAIL = "threeSlides.ppt";
public static SlideShow createPpt(String fileName) throws
IOException {
//retrieve or create the presentation
SlideShow ppt = null;
File file = new File(fileName);
if(file.exists()) {
ppt = new SlideShow(new FileInputStream(file));
} else {
ppt = new SlideShow();
}
return ppt;
}
public static void savePpt(String fileName, SlideShow ppt) throws
FileNotFoundException, IOException {
FileOutputStream out = new FileOutputStream(fileName);
ppt.write(out);
out.close();
}
public static void main(String[] args) {
try {
//build the non-corrupt ppt
System.out.print("Generating two slide ppt...");
SlideShow pptPass = createPpt(FILE_NAME_PASS);
savePpt(FILE_NAME_PASS, pptPass);
//create slide1
pptPass.createSlide();
savePpt(FILE_NAME_PASS, pptPass);
//create slide2
pptPass.createSlide();
savePpt(FILE_NAME_PASS, pptPass);
//build the corrupt ppt
System.out.print("Generating three slide ppt...");
SlideShow pptFail = createPpt(FILE_NAME_FAIL);
//create slide1
pptFail.createSlide();
savePpt(FILE_NAME_FAIL, pptFail);
//create slide2
pptFail.createSlide();
savePpt(FILE_NAME_FAIL, pptFail);
//create slide3
pptFail.createSlide();
savePpt(FILE_NAME_FAIL, pptFail);
System.out.println("COMPLETE");
} catch(Throwable e) {
System.err.println(e.getMessage());
System.err.println(e);
}
}
}
-----Original Message-----
From: Yegor Kozlov [mailto:[email protected]]
Sent: Thursday, January 21, 2010 12:55 AM
To: POI Users List
Subject: Re: 3rd PowerPoint Slide is Corrupt
Does your code run on server side? I wonder if it is a concurrency
issue.
Which version of POI?
Can you create a bug in Bugzilla and attach sample code to reproduce
the
problem (ideally a junit test case) and two ppt
files: one with two slides, not corrupted and the other with 3
slides,
corrupted.
Yegor
Hi,
I'm using the POI project to generate some PowerPoint slides. It
works
fine until I generate the 3rd slide for my slide deck, which ends
up
being corrupted every time. The first time my program runs it
creates
a
new slide deck and adds a single slide to it. After that, every
time
the
program runs it grabs the slide deck generated during the first run
and
appends a single slide to it. After the first run of the program
the
slide deck is fine. After the second run it is fine as well. The
third
run generates a corrupt slide every time. For testing purposes I
changed
my program so that all 3 runs of the program are generating the
identical blank slide and yet this corruption still happens, so it
does
not appear to have anything to do with my slide contents. I am
following
the code samples given on the POI website under "Shapes How To":
To create the slide deck during the first run:
SlideShow ppt = new SlideShow();
To connect to an existing slide deck during subsequent runs:
SlideShow ppt = null;
File pptFile = new File(pptFileName);
if(pptFile.exists()) {
if(pptFile.canWrite()) {
//construct the ppt from an existing file
ppt = new SlideShow(new FileInputStream(pptFile));
} else {
throw new IOException("Unable to write to the PowerPoint file
'"
+ pptFileName + "'");
}
}
To add a blank slide to the slide deck (nothing fancy here):
Slide slide = ppt.createSlide();
To save my slide deck after adding a slide:
FileOutputStream out = new FileOutputStream(pptFileName);
ppt.write(out);
out.close();
This all seems very straightforward and so I am not sure why the
third
slide is always corrupted. Also, if I use my program to generate 2
slides and then I add a third slide through PowerPoint, I can
continue
adding slides to the slide deck without any corruption. I can also
create a blank slide deck through PowerPoint and then use my
program
to
append blank slides to the deck and no corruption happens. So this
leads
me to believe it has something to do with the saving of my
PowerPoint
slide deck, since whenever I save it through PowerPoint the
corruption
does not occur.
I appreciate any help.
Thanks in advance.
Joe
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