如何使用Ruby和Nokogiri解析Google图像URL？
我正试图在谷歌图像网页上制作一个包含所有图像文件的数组 我需要一个正则表达式来提取imagurl=之后的所有内容，并在&之前结束，如下图所示：如何使用Ruby和Nokogiri解析Google图像URL？,ruby,regex,rubygems,nokogiri,Ruby,Regex,Rubygems,Nokogiri,我正试图在谷歌图像网页上制作一个包含所有图像文件的数组 我需要一个正则表达式来提取imagurl=之后的所有内容，并在&之前结束，如下图所示： <a href="http://www.google.com/imgres?imgurl=http://www.trendytree.com/old-world- christmas/images/20031chapel20031-silent-night-chapel.jpg&imgrefurl=http://www.t
<a href="http://www.google.com/imgres?imgurl=http://www.trendytree.com/old-world- christmas/images/20031chapel20031-silent-night-chapel.jpg&imgrefurl=http://www.trendytree.com/old-world-christmas/silent-night-chapel-20031-christmas-ornament-old-world-christmas.html&usg=__YJdf3xc4ydSfLQa9tYnAzavKHYQ=&h=400&w=400&sz=58&hl=en&start=19&zoom=1&tbnid=ajDcsGGs0tgE9M:&tbnh=124&tbnw=124&ei=qagfUbXmHKfv0QHI3oG4CQ&itbs=1&sa=X&ved=0CE4QrQMwEg"><img height="124" width="124" src="https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRLy5inpSdHxWuE7z3QSZw35JwN3upbBaLr11LR25noTKbSMn9-qrySSg"></a><br><cite title="trendytree.com">trendytree.com</cite><br>Silent Night Chapel <b>20031</b><br>400 × 400 - 58k - jpg</td>
str = '<a href="http://www.google.com/imgres?imgurl=http://www.trendytree.com/old-world- christmas/images/20031chapel20031-silent-night-chapel.jpg&imgrefurl=http://www.trendytree.com/old-world-christmas/silent-night-chapel-20031-christmas-ornament-old-world-christmas.html&usg=__YJdf3xc4ydSfLQa9tYnAzavKHYQ=&h=400&w=400&sz=58&hl=en&start=19&zoom=1&tbnid=ajDcsGGs0tgE9M:&tbnh=124&tbnw=124&ei=qagfUbXmHKfv0QHI3oG4CQ&itbs=1&sa=X&ved=0CE4QrQMwEg"><img height="124" width="124" src="https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRLy5inpSdHxWuE7z3QSZw35JwN3upbBaLr11LR25noTKbSMn9-qrySSg"></a><br><cite title="trendytree.com">trendytree.com</cite><br>Silent Night Chapel <b>20031</b><br>400 × 400 - 58k - jpg</td>'
str.split('imgurl=')[1].split('&')[0]
#=> "http://www.trendytree.com/old-world- christmas/images/20031chapel20031-silent-night-chapel.jpg"
这就是你想要的吗？要获得你想要的所有img URL
# get all links
url = 'some-google-images-url'
links = Nokogiri::HTML( open(url) ).css('a')
# get regex match or nil on desired img
img_urls = links.map {|a| a['href'][/imgurl=(.*?)&/, 1] }
# get rid of nils
img_urls.compact
您需要的正则表达式是/imgurl=.*？&/因为您需要imgurl=和&之间的非贪婪匹配，否则贪婪的.*会将所有内容都保留到字符串中的最后一个。以获取您想要的所有img URL
# get all links
url = 'some-google-images-url'
links = Nokogiri::HTML( open(url) ).css('a')
# get regex match or nil on desired img
img_urls = links.map {|a| a['href'][/imgurl=(.*?)&/, 1] }
# get rid of nils
img_urls.compact
您想要的正则表达式是/imgurl=.*？&/因为您想要imgurl=和&之间的非贪婪匹配，否则贪婪的.*将把字符串中的所有内容都排到最后。使用正则表达式的问题是您对URL中参数的顺序有过多的了解。如果订单发生变化，或&；这个正则表达式不起作用 而是解析URL，然后将值拆分为：
# encoding: UTF-8
require 'nokogiri'
require 'cgi'
require 'uri'
doc = Nokogiri::HTML.parse('<a href="http://www.google.com/imgres?imgurl=http://www.trendytree.com/old-world-christmas/images/20031chapel20031-silent-night-chapel.jpg&imgrefurl=http://www.trendytree.com/old-world-christmas/silent-night-chapel-20031-christmas-ornament-old-world-christmas.html&usg=__YJdf3xc4ydSfLQa9tYnAzavKHYQ=&h=400&w=400&sz=58&hl=en&start=19&zoom=1&tbnid=ajDcsGGs0tgE9M:&tbnh=124&tbnw=124&ei=qagfUbXmHKfv0QHI3oG4CQ&itbs=1&sa=X&ved=0CE4QrQMwEg"><img height="124" width="124" src="https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRLy5inpSdHxWuE7z3QSZw35JwN3upbBaLr11LR25noTKbSMn9-qrySSg"></a><br><cite title="trendytree.com">trendytree.com</cite><br>Silent Night Chapel <b>20031</b><br>400 × 400 - 58k - jpg</td>')
img_url = doc.search('a').each do |a|
query_params = CGI::parse(URI(a['href']).query)
puts query_params['imgurl']
end
Hash[URI(a['href']).query.split('&').map{ |p| p.split('=') }]
使用正则表达式的问题在于，您对URL中参数的顺序有过多的了解。如果订单发生变化，或&；这个正则表达式不起作用 而是解析URL，然后将值拆分为：
# encoding: UTF-8
require 'nokogiri'
require 'cgi'
require 'uri'
doc = Nokogiri::HTML.parse('<a href="http://www.google.com/imgres?imgurl=http://www.trendytree.com/old-world-christmas/images/20031chapel20031-silent-night-chapel.jpg&imgrefurl=http://www.trendytree.com/old-world-christmas/silent-night-chapel-20031-christmas-ornament-old-world-christmas.html&usg=__YJdf3xc4ydSfLQa9tYnAzavKHYQ=&h=400&w=400&sz=58&hl=en&start=19&zoom=1&tbnid=ajDcsGGs0tgE9M:&tbnh=124&tbnw=124&ei=qagfUbXmHKfv0QHI3oG4CQ&itbs=1&sa=X&ved=0CE4QrQMwEg"><img height="124" width="124" src="https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRLy5inpSdHxWuE7z3QSZw35JwN3upbBaLr11LR25noTKbSMn9-qrySSg"></a><br><cite title="trendytree.com">trendytree.com</cite><br>Silent Night Chapel <b>20031</b><br>400 × 400 - 58k - jpg</td>')
img_url = doc.search('a').each do |a|
query_params = CGI::parse(URI(a['href']).query)
puts query_params['imgurl']
end
Hash[URI(a['href']).query.split('&').map{ |p| p.split('=') }]