使用Perl解析XML文件

Question

I am trying to extract the value of two particular attributes from an XML file, whose structure is below;

<environment>
    <applications>
       <application1>
          <app-config>
             <server host="boxA" port="1234"/>
           </app-config>
       </applicaitons> 
</environment>

I want to be able to read the value of the attribute "host" and "port".

I've tried with the foillowing piece of code but this doesn't work for me.

#!/usr/local/bin/perl -w

use XML::XPath;

my $file = "configuration.xml";
my $xp = XML::XPath->new(filename => $file);

my $hname = $xp->find('/environment/applications/application1/app-config/server/@host');
my $pnumber = $xp->find('/environment/applications/application1/app-config/server/@port');


print $hname;

But this does not return any output whatsoever when I run this command.

Thanks in advance

Answer 1

Your XML is invalid! Fix it and it works fine.

$ perl test.pl
boxA

Answer 2

Always, always start your perl scripts with;

use strict;

And while debugging, also do this;

use warnings;

That will show you that your XML is malformed to start with.

Fix your XML and it will work!

Answer 3

</applicaitons> should be spelled as </applications> Replace that in your XML document. The source is fine.

Answer 4

Use XML:Simple. Its, well, simple.

Trying the following code:

use strict;
use warnings;
use XML::Simple;
my $xml = XMLin( <<XML );
<environment>
    <applications>
       <application1>
          <app-config>
             <server host="boxA" port="1234"/>
           </app-config>
       </applicaitons> 
</environment>
XML
print $xml->{"applications"}{"app-config"}{"server"}{"host"} . "\n";
print $xml->{"applications"}{"app-config"}{"server"}{"port"} . "\n";

on your XML snippet, you'll get back an error such as:

mismatched tag at line 7, column 9, byte 159 at C:/Perl64/lib/XML/Parser.pm line 187

since its telling me there's a mismatched tag, I start examining the XML until I work out the malformed issues so I work on the XML errors until I come up with:

use strict;
use warnings;
use XML::Simple;
my $xml = XMLin( <<XML );
<environment>
    <applications>
          <app-config>
             <server host="boxA" port="1234"/>
           </app-config>
       </applications> 
</environment>
XML
print $xml->{"applications"}{"app-config"}{"server"}{"host"} . "\n";
print $xml->{"applications"}{"app-config"}{"server"}{"port"} . "\n";

And now the program yields the expected:

boxA
1234

As you can see, it helped me quickly discover the source of the error and with no extra configuration XML::Simple made a very natural mapping to the perl hashes that we all love so well :-) ... simple.