初识nokogiri

Nokogiri是一个HTML、XML、SAX等解析器。它可以通过CSS3或者XPath来检索文档。具有如下特征：

• XML/HTML DOM parser which handles broken HTML
• XML/HTML SAX parser
• XML/HTML Push parser
• XPath 1.0 support for document searching
• CSS3 selector support for document searching
• XML/HTML builder
• XSLT transformer

安装命令：

gem install nokogiri

这里截取官网上的一段代码示例：

require 'nokogiri'
require 'open-uri'

# Fetch and parse HTML document
doc = Nokogiri::HTML(open('http://www.nokogiri.org/tutorials/installing_nokogiri.html'))

puts "### Search for nodes by css"
doc.css('nav ul.menu li a', 'article h2').each do |link|
  puts link.content
end

puts "### Search for nodes by xpath"
doc.xpath('//nav//ul//li/a', '//article//h2').each do |link|
  puts link.content
end

puts "### Or mix and match."
doc.search('nav ul.menu li a', '//article//h2').each do |link|
  puts link.content
end

运行结果如下：