in reply to Converting PDF file to text

I had good success with using Apache Tika for text extraction from PDFs (also, Apache::Tika::Async).

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Re^2: Converting PDF file to text
by cerian (Novice) on May 12, 2017 at 17:13 UTC
    Invoking java on the tika-app-1.14.jar from within perl works fine on my laptop, but not on web site this thing is for. It generates the following trace: 
    Exception in thread "main" java.lang.ClassFormatError: org.apache.tika.cli.TikaCLI (unrecognized class file version)
   at java.lang.VMClassLoader.defineClass(libgcj.so.10)
   at java.lang.ClassLoader.defineClass(libgcj.so.10)
   at java.security.SecureClassLoader.defineClass(libgcj.so.10)
   at java.net.URLClassLoader.findClass(libgcj.so.10)
   at java.lang.ClassLoader.loadClass(libgcj.so.10)
   at java.lang.ClassLoader.loadClass(libgcj.so.10)
   at gnu.java.lang.MainThread.run(libgcj.so.10)
    I've been attempting to work with the Apache::Tika, Apache::Tika::Asynch, and Apache::Tika::Server modules; but without success. The only documentation I have found for them so far is the brief synopsis section on CPAN. Sadly, those contain errors. Do you have any additional documentation or working code snippets? I have yet to make one of these critters work. Examples of what I've tried are below:

    Attempt 1: Apache::Tika 
    use Apache::Tika;

my $tika = Apache::Tika->new();
open my $fh, '<:raw', 'x.pdf';
my $pdf = do { local $/; <$fh> };
close $fh;

my $text = $tika->tika($pdf);
print "$text\n";

    [download]
    The value in $text is: 
    Can't connect to localhost:9998 (Connection refused)

LWP::Protocol::http::Socket: connect: Connection refused at /Library/Perl/5.18/LWP/Protocol/http.pm line 46.
    Attempt 2: Apache::Tika::Asynch 
    use Apache::Tika::Async;
 
my $tika= Apache::Tika::Server->new;
 
my $fn= shift;
 
use Data::Dumper;
print Dumper $tika->get_meta($fn);
print Dumper $tika->get_text($fn);

    [download]

    That *is* the CPAN synopsis. It doesn't work. It will die on line 2 with Can't locate object method "new" via package "Apache::Tika::Server" Additionally, there is no new() method within the Apache::Tika::Async class.

    Attempt 3: Apache::Tika::Server 
    use Data::Dumper;
use Apache::Tika::Server;

my $tika= Apache::Tika::Server->new();
#    $tika->launch();  

my $fn = "x.pdf";
print Dumper $tika->get_text($fn);

    [download]

    This gets me the following: Got HTTP error code 595 on the call to $tika->get_text. If I uncomment the call to $tika->launch, I get: Use of uninitialized value in join or string at /Library/Perl/5.18/Apache/Tika/Server.pm line 81.

    So far I can find no other information on these libraries on-line. If anyone out there has some documentation or working examples on how to use them, I would love to see it.
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      Most likely the version of Java on your web server does not work with the version of Java the Tika JAR file requires. I can't help you there.

      I'm sorry that the synopsis of Apache::Tika::Async is broken - it should look like the following, but it seems I never released that fix onto CPAN:

          use Apache::Tika::Async;

    my $tika= Apache::Tika::Async->new;

    my $fn= shift;

    use Data::Dumper;
    my $info = $tika->get_all( $fn );
    print Dumper $info->meta($fn);
    print $info->content($fn);
    # <html><body>...
    print $info->meta->{"meta:language"};
    # en

      [download]

      But all of this is in vain if the Tika executable won't start.

      Update: I've now published the Git repository of the module, which contains some fixes I should also release soonish.

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