7

我想从此页面获取数据：

http://www.canadapost.ca/cpotools/apps/track/personal/findByTrackNumber?trackingNumber=0656887000494793

但该页面转发到：

http://www.canadapost.ca/cpotools/apps/track/personal/findByTrackNumber?execution=eXs1

因此，当我open从 OpenUri 使用 来尝试获取数据时，它会抛出一个RuntimeError错误说HTTP redirection loop:

我不确定如何在重定向并引发该错误后获取该数据。

4

3 回答 3

23

你需要一个像Mechanize这样的工具。从它的描述来看：

Mechanize 库用于自动与网站交互。Mechanize 自动存储和发送 cookie、跟踪重定向、可以跟踪链接和提交表单。可以填充和提交表单字段。Mechanize 还会记录您访问过的网站作为历史记录。

这正是您所需要的。所以，

sudo gem install mechanize

然后

require 'mechanize'
agent = WWW::Mechanize.new
page = agent.get "http://www.canadapost.ca/cpotools/apps/track/personal/findByTrackNumber trackingNumber=0656887000494793"

page.content # Get the resulting page as a string
page.body # Get the body content of the resulting page as a string
page.search(".somecss") # Search for specific elements by XPath/CSS using nokogiri

你已经准备好摇滚了。

于 2010-05-07T19:42:33.473 回答
1

该站点似乎正在使用会话执行一些重定向逻辑。如果您不发回他们在第一次请求时发送的会话 cookie，您将最终进入重定向循环。恕我直言，这对他们来说是一个糟糕的实现。

然而，我试图将 cookie 传回给他们，但我没有让它工作，所以我不能完全确定这就是这里发生的一切。

于 2010-05-03T18:33:55.133 回答
1

虽然机械化是一个很棒的工具，但我更喜欢“烹饪”我自己的东西。

如果您对解析很认真，可以查看此代码。它每天可以在国际级别上抓取数千个站点，据我研究和调整，没有更稳定的方法可以让您以后根据需要进行高度定制。

require "open-uri"
require "zlib"
require "nokogiri"
require "sanitize"
require "htmlentities"
require "readability"

def crawl(url_address)
self.errors = Array.new
begin
  begin
    url_address = URI.parse(url_address)
  rescue URI::InvalidURIError
    url_address = URI.decode(url_address)
    url_address = URI.encode(url_address)
    url_address = URI.parse(url_address)
  end
  url_address.normalize!
  stream = ""
  timeout(8) { stream = url_address.open(SHINSO_HEADERS) }
  if stream.size > 0
    url_crawled = URI.parse(stream.base_uri.to_s)
  else
    self.errors << "Server said status 200 OK but document file is zero bytes."
    return
  end
rescue Exception => exception
  self.errors << exception
  return
end
# extract information before html parsing
self.url_posted       = url_address.to_s
self.url_parsed       = url_crawled.to_s
self.url_host         = url_crawled.host
self.status           = stream.status
self.content_type     = stream.content_type
self.content_encoding = stream.content_encoding
self.charset          = stream.charset
if    stream.content_encoding.include?('gzip')
  document = Zlib::GzipReader.new(stream).read
elsif stream.content_encoding.include?('deflate')
  document = Zlib::Deflate.new().deflate(stream).read
#elsif stream.content_encoding.include?('x-gzip') or
#elsif stream.content_encoding.include?('compress')
else
  document = stream.read
end
self.charset_guess = CharGuess.guess(document)
if not self.charset_guess.blank? and (not self.charset_guess.downcase == 'utf-8' or not self.charset_guess.downcase == 'utf8')
  document = Iconv.iconv("UTF-8", self.charset_guess, document).to_s
end
document = Nokogiri::HTML.parse(document,nil,"utf8")
document.xpath('//script').remove
document.xpath('//SCRIPT').remove
for item in document.xpath('//*[translate(@src, "ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghijklmnopqrstuvwxyz")]')
  item.set_attribute('src',make_absolute_address(item['src']))
end
document = document.to_s.gsub(/<!--(.|\s)*?-->/,'')
self.content = Nokogiri::HTML.parse(document,nil,"utf8")
end
于 2012-09-26T15:21:33.527 回答