日本語を含むパースはダメみたい。
irb(main):008:0> URI.parse("http://www.example.com/あ.html")
URI::InvalidURIError: bad URI(is not URI?): http://www.example.com/あ.html
from /usr/lib/ruby/1.8/uri/common.rb:436:in `split'
from /usr/lib/ruby/1.8/uri/common.rb:485:in `parse'
from (irb):8
from :0
irb(main):002:0> URI.parse("http://www.example.com/" + URI.encode("あ") + ".html")
=> #
