在 Ruby 中发出 HEAD 请求

Question

我对 ruby 有点陌生，有 python 背景 我想向 URL 发出头请求并检查一些信息，例如文件是否存在于服务器上以及时间戳、etag 等，我无法在 RUBY 中完成此操作。

在Python中：

import httplib2
print httplib2.Http().request('url.com/file.xml','HEAD')

在 Ruby 中：我尝试了这个并抛出了一些错误

require 'net/http'

Net::HTTP.start('url.com'){|http|
   response = http.head('/file.xml')
}
puts response


SocketError: getaddrinfo: nodename nor servname provided, or not known
    from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:877:in `initialize'
    from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:877:in `open'
    from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:877:in `block in connect'
    from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/timeout.rb:51:in `timeout'
    from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:876:in `connect'
    from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:861:in `do_start'
    from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:850:in `start'
    from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:582:in `start'
    from (irb):2
    from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/bin/irb:16:in `<main>'

Answer 1

我意识到这个问题已经得到解答，但我也必须经历一些困难。这是更具体的开始：

#!/usr/bin/env ruby

require 'net/http'
require 'net/https' # for openssl

uri = URI('http://stackoverflow.com')
path = '/questions/16325918/making-head-request-in-ruby'

response=nil
http = Net::HTTP.new(uri.host, uri.port)
# http.use_ssl = true                            # if using SSL
# http.verify_mode = OpenSSL::SSL::VERIFY_NONE   # for example, when using self-signed certs

response = http.head(path)
response.each { |key, value| puts key.ljust(40) + " : " + value }

Answer 2

我认为向 :start 传递一个字符串还不够； 在文档中看起来它需要 URI 对象的主机和端口才能获得正确的地址：

uri = URI('http://example.com/some_path?query=string')

Net::HTTP.start(uri.host, uri.port) do |http|
  request = Net::HTTP::Get.new uri

  response = http.request request # Net::HTTPResponse object
end

你可以试试这个：

require 'net/http'

url = URI('yoururl.com')

Net::HTTP.start(url.host, url.port){|http|
   response = http.head('/file.xml')
   puts response
}

我注意到一件事 - 你的

puts response

需要在街区内！否则，变量

response

不在范围内。

编辑：您还可以将响应视为散列以获取标头的值：

response.each_value { |value| puts value }

Answer 3

headers = nil

uri = URI('http://my-bucket.amazonaws.com/filename.mp4')

Net::HTTP.start(uri.host, uri.port) do |http|
  headers = http.head(uri.path).to_hash
end

现在您在

headers

中拥有了标题的哈希值