You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@pdfbox.apache.org by Systema Sephiroticum <fa...@gmail.com> on 2017/01/05 19:57:10 UTC
Casting confusion
I've been tasked with traversing a PDF files for embedded links, i.e.
anchors added in winword and what have you. Due to different ways URLs can
be embedded in PDFs, and the variety of nesting levels and ordering, it's
proving a challenge.
I can see in my IDE the URL that I need to acquire is nested deep in the
COSBase's basObject property, but baseObject is private, so I can't
toString() it. To make matters worse, toString() on the COSObject itself
returns me only the top level object rather than the entire contents--if
there were a to get the stringified baseObject's contents, I would be done
with this by now.
My example method is a bit long for email so I put it on pastebin. It's
compiles, but is borderline-pseudocode so there's no need to look at it
unless the rest of this email is unclear.
http://pastebin.com/LvXu0tNh
I'm curious what to do after getting an object from an array as such:
COSObject obj = (COSObject) cosArr.get(i);
At this point I can see the obj's baseObject, like I said, but to acquire
it I have to attempt all sorts of casts to COSDictionary, catch the
ClassCastExceptions and try again, with nullchecks on retrieved objects at
every step. Am I doing this wrong? I haven't been able to find a pattern
for this that isn't ugly as sin. If anyone could point me to examples of
how COSObject.getItem() is supposed to be used in different situations,
that would be great.
Finally, assuming that there really is no way to avoid all this casting,
are there any casts with PDFBox that I can be assured will not result in a
ClassCastException? Specifically, casts to COSArray and COSObject.
Sorry for the haphazard nature of this email, I'm still trying to figure
out exactly all the things about this that I don't understand.
Re: Casting confusion
Posted by Systema Sephiroticum <fa...@gmail.com>.
Thanks for the quick reply, that was pretty much what I needed! I didn't
know there was such an example in the source, really appreciate this tip.
On Thu, Jan 5, 2017 at 12:31 PM, Tilman Hausherr <TH...@t-online.de>
wrote:
> Hi,
>
> Seems you're taking a very low level approach there. Please try the
> PrintURLs example from the source code download.
>
> If this doesn't answer your question, please share the PDF, i.e. upload it
> somewhere.
>
> Re your question about "cosArr.get(i);"
>
> That can be anything. It gets a bit easier if you do getObject(i), this
> will dereference if needed.
>
> Tilman
>
>
> Am 05.01.2017 um 20:57 schrieb Systema Sephiroticum:
>
>> I've been tasked with traversing a PDF files for embedded links, i.e.
>> anchors added in winword and what have you. Due to different ways URLs can
>> be embedded in PDFs, and the variety of nesting levels and ordering, it's
>> proving a challenge.
>>
>> I can see in my IDE the URL that I need to acquire is nested deep in the
>> COSBase's basObject property, but baseObject is private, so I can't
>> toString() it. To make matters worse, toString() on the COSObject itself
>> returns me only the top level object rather than the entire contents--if
>> there were a to get the stringified baseObject's contents, I would be done
>> with this by now.
>>
>> My example method is a bit long for email so I put it on pastebin. It's
>> compiles, but is borderline-pseudocode so there's no need to look at it
>> unless the rest of this email is unclear.
>> http://pastebin.com/LvXu0tNh
>>
>> I'm curious what to do after getting an object from an array as such:
>> COSObject obj = (COSObject) cosArr.get(i);
>>
>> At this point I can see the obj's baseObject, like I said, but to acquire
>> it I have to attempt all sorts of casts to COSDictionary, catch the
>> ClassCastExceptions and try again, with nullchecks on retrieved objects at
>> every step. Am I doing this wrong? I haven't been able to find a pattern
>> for this that isn't ugly as sin. If anyone could point me to examples of
>> how COSObject.getItem() is supposed to be used in different situations,
>> that would be great.
>>
>> Finally, assuming that there really is no way to avoid all this casting,
>> are there any casts with PDFBox that I can be assured will not result in a
>> ClassCastException? Specifically, casts to COSArray and COSObject.
>>
>> Sorry for the haphazard nature of this email, I'm still trying to figure
>> out exactly all the things about this that I don't understand.
>>
>>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@pdfbox.apache.org
> For additional commands, e-mail: users-help@pdfbox.apache.org
>
>
Re: Casting confusion
Posted by Tilman Hausherr <TH...@t-online.de>.
Hi,
Seems you're taking a very low level approach there. Please try the
PrintURLs example from the source code download.
If this doesn't answer your question, please share the PDF, i.e. upload
it somewhere.
Re your question about "cosArr.get(i);"
That can be anything. It gets a bit easier if you do getObject(i), this
will dereference if needed.
Tilman
Am 05.01.2017 um 20:57 schrieb Systema Sephiroticum:
> I've been tasked with traversing a PDF files for embedded links, i.e.
> anchors added in winword and what have you. Due to different ways URLs can
> be embedded in PDFs, and the variety of nesting levels and ordering, it's
> proving a challenge.
>
> I can see in my IDE the URL that I need to acquire is nested deep in the
> COSBase's basObject property, but baseObject is private, so I can't
> toString() it. To make matters worse, toString() on the COSObject itself
> returns me only the top level object rather than the entire contents--if
> there were a to get the stringified baseObject's contents, I would be done
> with this by now.
>
> My example method is a bit long for email so I put it on pastebin. It's
> compiles, but is borderline-pseudocode so there's no need to look at it
> unless the rest of this email is unclear.
> http://pastebin.com/LvXu0tNh
>
> I'm curious what to do after getting an object from an array as such:
> COSObject obj = (COSObject) cosArr.get(i);
>
> At this point I can see the obj's baseObject, like I said, but to acquire
> it I have to attempt all sorts of casts to COSDictionary, catch the
> ClassCastExceptions and try again, with nullchecks on retrieved objects at
> every step. Am I doing this wrong? I haven't been able to find a pattern
> for this that isn't ugly as sin. If anyone could point me to examples of
> how COSObject.getItem() is supposed to be used in different situations,
> that would be great.
>
> Finally, assuming that there really is no way to avoid all this casting,
> are there any casts with PDFBox that I can be assured will not result in a
> ClassCastException? Specifically, casts to COSArray and COSObject.
>
> Sorry for the haphazard nature of this email, I'm still trying to figure
> out exactly all the things about this that I don't understand.
>
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@pdfbox.apache.org
For additional commands, e-mail: users-help@pdfbox.apache.org