Check if Internet Connection Exists with Ruby?

问题:

Just asked how to check if an internet connection exists using javascript and got some great answers. What's the easiest way to do this in Ruby? In trying to make generated html markup code as clean as possible, I'd like to conditionally render the script tag for javascript files depending on whether or not an internet condition. Something like (this is HAML):

- if internet_connection?
    %script{:src => "http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js", :type => "text/javascript"}
- else
    %script{:src => "/shared/javascripts/jquery/jquery.js", :type => "text/javascript"}

回答1:

You can use the Ping class.

require 'resolv-replace'
require 'ping'

def internet_connection?
  Ping.pingecho "google.com", 1, 80
end

The method returns true or false and doesn't raise exceptions.

回答2:

require 'open-uri'

def internet_connection?
  begin
    true if open("http://www.google.com/")
  rescue
    false
  end
end

This is closer to what the OP is looking for. It works in Ruby 1.8 and 1.9. It's a bit cleaner too.

回答3:

I love how everyone simply assume that googles servers are up. Creds to google.

If you want to know if you have internet without relying on google, then you could use DNS to see if you are able to get a connection.

You can use Ruby DNS Resolv to try to translate a url into an ip address. Works for Ruby version 1.8.6+

So:

#The awesome part: resolv is in the standard library

def has_internet?
  require "resolv"
  dns_resolver = Resolv::DNS.new()
  begin
    dns_resolver.getaddress("symbolics.com")#the first domain name ever. Will probably not be removed ever.
    return true
  rescue Resolv::ResolvError => e
    return false
  end
end

Hope this helps someone out :)

回答4:

Same basics as in Simone Carletti's answer but compatible with Ruby 2:

# gem install "net-ping"

require "net/ping"

def internet_connection?
  Net::Ping::External.new("8.8.8.8").ping?
end

回答5:

require 'open-uri'

page = "http://www.google.com/"
file_name = "output.txt"
output = File.open(file_name, "a")
begin
  web_page = open(page, :proxy_http_basic_authentication => ["http://your.company.proxy:80/", "your_user_name", "your_user_password"])  
  output.puts "#{Time.now}: connection established - OK !" if web_page
rescue Exception
  output.puts "#{Time.now}: Connection failed !"
  output.close
ensure
  output.close
end

回答6:

def connected?
  !!Socket.getaddrinfo("google.com", "http")  
rescue SocketError => e
  e.message != 'getaddrinfo: nodename nor servname provided, or not known'
end

Since it uses a hostname the first thing it needs to do is DNS lookup, which causes the exception if there is no internet connection.