Question

我正在尝试在Google图片网页上制作所有图片文件的数组。

我想要一个正则表达式来提取"imagurl="之后的所有内容并在"&amp"之前结束，如此HTML中所示：

<a href="http://www.google.com/imgres?imgurl=http://www.trendytree.com/old-world-   christmas/images/20031chapel20031-silent-night-chapel.jpg&amp;imgrefurl=http://www.trendytree.com/old-world-christmas/silent-night-chapel-20031-christmas-ornament-old-world-christmas.html&amp;usg=__YJdf3xc4ydSfLQa9tYnAzavKHYQ=&amp;h=400&amp;w=400&amp;sz=58&amp;hl=en&amp;start=19&amp;zoom=1&amp;tbnid=ajDcsGGs0tgE9M:&amp;tbnh=124&amp;tbnw=124&amp;ei=qagfUbXmHKfv0QHI3oG4CQ&amp;itbs=1&amp;sa=X&amp;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>

我觉得我可以用正则表达式来做这件事，但我找不到使用正则表达式搜索我解析的文档的方法，但我找不到任何解决方案。

Answer 1

str = '<a href="http://www.google.com/imgres?imgurl=http://www.trendytree.com/old-world-     christmas/images/20031chapel20031-silent-night-chapel.jpg&amp;imgrefurl=http://www.trendytree.com/old-world-christmas/silent-night-chapel-20031-christmas-ornament-old-world-christmas.html&amp;usg=__YJdf3xc4ydSfLQa9tYnAzavKHYQ=&amp;h=400&amp;w=400&amp;sz=58&amp;hl=en&amp;start=19&amp;zoom=1&amp;tbnid=ajDcsGGs0tgE9M:&amp;tbnh=124&amp;tbnw=124&amp;ei=qagfUbXmHKfv0QHI3oG4CQ&amp;itbs=1&amp;sa=X&amp;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('&amp')[0]
#=> "http://www.trendytree.com/old-world-     christmas/images/20031chapel20031-silent-night-chapel.jpg"

这就是你要找的东西吗？

Answer 2

使用正则表达式的问题是您对URL中参数的顺序有太多了解。如果订单发生变化，或&消失，则正则表达式将无效。

而是解析URL，然后将值拆分出来：

# 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&amp;imgrefurl=http://www.trendytree.com/old-world-christmas/silent-night-chapel-20031-christmas-ornament-old-world-christmas.html&amp;usg=__YJdf3xc4ydSfLQa9tYnAzavKHYQ=&amp;h=400&amp;w=400&amp;sz=58&amp;hl=en&amp;start=19&amp;zoom=1&amp;tbnid=ajDcsGGs0tgE9M:&amp;tbnh=124&amp;tbnw=124&amp;ei=qagfUbXmHKfv0QHI3oG4CQ&amp;itbs=1&amp;sa=X&amp;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

哪个输出：

http://www.trendytree.com/old-world-christmas/images/20031chapel20031-silent-night-chapel.jpg

使用URI和CGI是因为URI decode_www_form在尝试解码查询时引发异常。

我也知道使用类似的东西将查询字符串解码为哈希：

Hash[URI(a['href']).query.split('&').map{ |p| p.split('=') }]

那将返回：

{"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"}

Answer 3

获取您想要的所有图片

# 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

你想要的正则表达式是/imgurl=(.*?)&/，因为你想要imgurl=和&之间的非贪婪匹配，否则贪婪的.*将把所有内容都带到最后& {{1}} 1}}在字符串中。

如何使用Ruby和Nokogiri解析Google图像URL？

3 个答案: