url = URI.parse('http://funonrails.com/categories/rails-3')
url.host #=> "http://funonrails.com"
url.port #=> 80

url = URI.parse('http://sandip:2121@funonrails.com/categories/rails-3')
url.user #=> "sandip"
url.password #=> "2121"

URI.extract('http://funonrails.com is rails blog authored by http://sandipransing.github.com contact mailto://sandip@funonrails.com')
#=> ["http://funonrails.com", "http://sandipransing.github.com", "mailto://sandip@funonrails.com"]

URI.split('http://sandip:2121@funonrails.com/categories/rails-3')
#=> ["http", "sandip:2121", "funonrails.com", nil, nil, "/categories/rails-3", nil, nil, nil]
 
<=> [Scheme, Userinfo, Host, Port, Registry, Path, Opaque, Query, Fragment]
 
URI.join('http://funonrails.com','categories/rails-3')
#=> #<URI::HTTP:0x7fbf9202efc8 URL:http://funonrails.com/categories/rails-3>

URI.escape "http://funonrails.com/categories/named scopes"
#=> "http://funonrails.com/categories/named%20scopes"
 
URI.encode "http://funonrails.com/categories/named scopes"
#=> "http://funonrails.com/categories/named%20scopes"
 
URI.decode "http://funonrails.com/categories/named%20scopes"
#=> "http://funonrails.com/categories/named scopes"
 
URI.unescape "http://funonrails.com/categories/named%20scopes"
#=> "http://funonrails.com/categories/named scopes"

# extract first URI from html_string
"ftp://localhost http://funonrails.com/categories/rails-3".slice(URI.regexp)
#=> "ftp://localhost"
 
# remove ftp URIs
"ftp://localhost http://funonrails.com/categories/rails-3".sub(URI.regexp(['ftp']))
#=> " http://funonrails.com/categories/rails-3"
 
# You should not rely on the number of parentheses
"ftp://localhost http://funonrails.com/categories/rails-3".scan(URI.regexp(['ftp'])) do |*matchs|
  p $&
  #=> ftp://localhost
end

request.request_uri
request.env['REQUEST_URI']

request.referrer