Can you provide examples of parsing HTML?-第3页回答

How do you parse HTML with a variety of languages and parsing libraries?

When answering:

Individual comments will be linked to in answers to questions about how to parse HTML with regexes as a way of showing the right way to do things.

For the sake of consistency, I ask that the example be parsing an HTML file for the href in anchor tags. To make it easy to search this question, I ask that you follow this format

Language: [language name]

Library: [library name]

[example code]

Please make the library a link to the documentation for the library. If you want to provide an example other than extracting links, please also include:

Purpose: [what the parse does]

标签： html language-agnostic html-parsing

29条回答

公子世无双

2楼-- · 2018-12-31 16:05

Language: PHP
Library: SimpleXML (and DOM)

<?php
$page = new DOMDocument();
$page->strictErrorChecking = false;
$page->loadHTMLFile('http://stackoverflow.com/questions/773340');
$xml = simplexml_import_dom($page);

$links = $xml->xpath('//a[@href]');
foreach($links as $link)
    echo $link['href']."\n";

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浅入江南

3楼-- · 2018-12-31 16:06

language: Python
library: HTMLParser

#!/usr/bin/python

from HTMLParser import HTMLParser

class FindLinks(HTMLParser):
    def __init__(self):
        HTMLParser.__init__(self)

    def handle_starttag(self, tag, attrs):
        at = dict(attrs)
        if tag == 'a' and 'href' in at:
            print at['href']


find = FindLinks()

html = "<html><body>"
for link in ("foo", "bar", "baz"):
    html += '<a href="http://%s.com">%s</a>' % (link, link)
html += "</body></html>"

find.feed(html)

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梦醉为红颜

4楼-- · 2018-12-31 16:06

language: Perl
library: HTML::Parser

#!/usr/bin/perl

use strict;
use warnings;

use HTML::Parser;

my $find_links = HTML::Parser->new(
    start_h => [
        sub {
            my ($tag, $attr) = @_;
            if ($tag eq 'a' and exists $attr->{href}) {
                print "$attr->{href}\n";
            }
        }, 
        "tag, attr"
    ]
);

my $html = join '',
    "<html><body>",
    (map { qq(<a href="http://$_.com">$_</a>) } qw/foo bar baz/),
    "</body></html>";

$find_links->parse($html);

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妖精总统

5楼-- · 2018-12-31 16:06

language: Ruby
library: Nokogiri

#!/usr/bin/env ruby

require "nokogiri"
require "open-uri"

doc = Nokogiri::HTML(open('http://www.example.com'))
hrefs = doc.search('a').map{ |n| n['href'] }

puts hrefs

Which outputs:

/
/domains/
/numbers/
/protocols/
/about/
/go/rfc2606
/about/
/about/presentations/
/about/performance/
/reports/
/domains/
/domains/root/
/domains/int/
/domains/arpa/
/domains/idn-tables/
/protocols/
/numbers/
/abuse/
http://www.icann.org/
mailto:iana@iana.org?subject=General%20website%20feedback

This is a minor spin on the one above, resulting in an output that is usable for a report. I only return the first and last elements in the list of hrefs:

#!/usr/bin/env ruby

require "nokogiri"
require "open-uri"

doc = Nokogiri::HTML(open('http://nokogiri.org'))
hrefs = doc.search('a[href]').map{ |n| n['href'] }

puts hrefs
  .each_with_index                     # add an array index
  .minmax{ |a,b| a.last <=> b.last }   # find the first and last element
  .map{ |h,i| '%3d %s' % [1 + i, h ] } # format the output

  1 http://github.com/tenderlove/nokogiri
100 http://yokolet.blogspot.com

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素衣白纱

6楼-- · 2018-12-31 16:06

Language: Java
Library: jsoup

import java.io.IOException;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import org.xml.sax.SAXException;

public class HtmlTest {
    public static void main(final String[] args) throws SAXException, ValidityException, ParsingException, IOException {
        final Document document = Jsoup.parse("<html><body><ul><li><a href=\"http://google.com\">google</li><li><a HREF=\"http://reddit.org\" target=\"_blank\">reddit</a></li><li><a name=\"nothing\">nothing</a><li></ul></body></html>");
        final Elements links = document.select("a[href]");
        for (final Element element : links) {
            System.out.println(element.attr("href"));
        }
    }
}

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刘海飞了

7楼-- · 2018-12-31 16:06

Language: JavaScript/Node.js

Library: Request and Cheerio

var request = require('request');
var cheerio = require('cheerio');

var url = "https://news.ycombinator.com/";
request(url, function (error, response, html) {
    if (!error && response.statusCode == 200) {
        var $ = cheerio.load(html);
        var anchorTags = $('a');

        anchorTags.each(function(i,element){
            console.log(element["attribs"]["href"]);
        });
    }
});

Request library downloads the html document and Cheerio lets you use jquery css selectors to target the html document.

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Can you provide examples of parsing HTML?

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