使用perl XML :: LibXML来如此缓慢地处理XML

Question

XML文件是这样的:

<?xml version="1.0" encoding="UTF-8"?>
<resource-data xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="resource-data.xsd">
  <class name="AP">
    <attributes>
      <resourceId>00 11 B5 1B 6D 20</resourceId>
      <lastModifyTime>20130107091545</lastModifyTime>
      <dcTime>20130107093019</dcTime>
      <attribute name="NMS_ID" value="DNMS" />
      <attribute name="IP_ADDR" value="10.11.141.111" />
      <attribute name="LABEL_DEV" value="00 11 B5 1B 6D 20" />
    </attributes>
        <attributes>
      <resourceId>00 11 B5 1B 6D 21</resourceId>
      <lastModifyTime>20130107091546</lastModifyTime>
      <dcTime>20130107093019</dcTime>
      <attribute name="NMS_ID" value="DNMS" />
      <attribute name="IP_ADDR" value="10.11.141.112" />
      <attribute name="LABEL_DEV" value="00 11 B5 1B 6D 21" />
    </attributes>
  </class>
</resource-data>

我的代码:

#!/usr/bin/perl

use Encode;
use XML::LibXML;
use Data::Dumper;

$parser = new XML::LibXML;
$struct = $parser->parse_file("d:/AP_201301073100_1.xml");

my $file_data = "d:\\ap.txt";
open IN, ">$file_data";

$rootel = $struct->getDocumentElement();
$elname = $rootel->getName();

@kids   = $rootel->getElementsByTagName('attributes');
foreach $child (@kids) {
  @atts = $child->getElementsByTagName('attribute');
  foreach $at (@atts) {
    $va = $at->getAttribute('value');
    print IN encode("gbk", "$va\t");
  }
  print IN encode("gbk", "\n");
}
close(IN);

我的问题是,如果XML文件只有80MB,那么程序将非常快,但是当XML文件大得多时,程序可能会非常慢.有人可以帮助我加快速度吗？

Answer 1

使用XML::Twig将允许您<attributes>在解析期间遇到处理每个元素,然后丢弃不再需要的XML数据.

这个程序似乎做你需要的.

use strict;
use warnings;

use XML::Twig;
use Encode;

use constant XML_FILE => 'S:/AP_201301073100_1.xml';
use constant OUT_FILE => 'D:/ap.txt';

open my $outfh, '>:encoding(gbk)', OUT_FILE or die $!;

my $twig = XML::Twig->new(twig_handlers => {attributes => \&attributes});
$twig->parsefile('myxml.xml');

sub attributes {
  my ($twig, $atts) = @_;
  my @values = map $_->att('value'), $atts->children('attribute');
  print $outfh join("\t", @values), "\n";
  $twig->purge;
}

产量

DNMS  10.11.141.111 00 11 B5 1B 6D 20
DNMS  10.11.141.112 00 11 B5 1B 6D 21