如何将图片从URL保存到磁盘

Question

我想从URL下载图片，比如：http://trinity.e-stile.ru/并将图像保存到类似"C:\pickaxe\pictures"的目录中。使用Nokogiri很重要。

我在这个网站上读到了类似的问题，但我没有发现它是如何工作的，我也不理解算法。

1. 我编写了解析URL的代码，并将带有"img"标记的部分网页源代码放入链接对象中：

   require 'nokogiri'
   require 'open-uri'
   PAGE_URL="http://trinity.e-stile.ru/"
   page=Nokogiri::HTML(open(PAGE_URL))   #parsing into object
   links=page.css("img") #object with html code with img tag
   puts links.length # it is 24 images on this url
   puts
   links.each{|i| puts i } #it looks like: <img border="0" alt="" src="/images/kroliku.jpg"> 
   puts
   puts
   links.each{|link| puts link['src'] } #/images/kroliku.jpg 
   

   获取HTML代码后，使用什么方法保存图片？

2. 如何将图像放入磁盘上的目录？

我更改了代码，但它有一个错误：

/home/action/.parts/packages/ruby2.1/2.1.1/lib/ruby/2.1.0/net/http.rb:879:in `initialize': getaddrinfo: Name or service not known (SocketError)

这是现在的代码：

require 'nokogiri'
require 'open-uri'
require 'net/http'
LOCATION = 'pics'
if !File.exist? LOCATION         # create folder if it is not exist
    require 'fileutils'
    FileUtils.mkpath LOCATION
end
#PAGE_URL = "http://ruby.bastardsbook.com/files/hello-webpage.html"
#PAGE_URL="http://trinity.e-stile.ru/"
PAGE_URL="http://www.youtube.com/"
page=Nokogiri::HTML(open(PAGE_URL))   
links=page.css("img")
links.each{|link| 
    Net::HTTP.start(PAGE_URL) do |http|
      localname = link.gsub /.*//, '' # left the filename only
      resp = http.get link['src']
      open("#{LOCATION}/#{localname}", "wb") do |file|
        file.write resp.body
      end
    end
 }

Answer 1

您差不多完成了。剩下的就是存储文件。让我们来做吧。

LOCATION = 'C:pickaxepictures'
if !File.exist? LOCATION         # create folder if it is not exist
    require 'fileutils'
    FileUtils.mkpath LOCATION
end
require 'net/http'
.... # your code with nokogiri etc.
links.each{|link| 
    Net::HTTP.start(PAGE_URL) do |http|
      localname = link.gsub /.*//, '' # left the filename only
      resp = http.get link['src']
      open("#{LOCATION}/#{localname}", "wb") do |file|
        file.write resp.body
      end
    end
end

就是这样。

Answer 2

正确的版本：

require 'nokogiri'
require 'open-uri'

LOCATION = 'pics'
if !File.exist? LOCATION         # create folder if it is not exist
    require 'fileutils'
    FileUtils.mkpath LOCATION
end
#PAGE_URL="http://trinity.e-stile.ru/"
PAGE_URL="http://www.youtube.com/"
page=Nokogiri::HTML(open(PAGE_URL)) 
links=page.css("img")
links.each{|link|
  uri = URI.join(PAGE_URL, link['src'] ).to_s # make absolute uri
  localname=File.basename(link['src'])
   File.open("#{LOCATION}/#{localname}",'wb') { |f| f.write(open(uri).read) }
  }