open_http：403禁止（OpenURI :: HTTPError）

Question

我正在尝试使用以下脚本从Google+ API中提取数据：

require 'open-uri'
require 'json'

google_api_key = 'put your google api key here'
page_id = '105672627985088123672'

data = open("https://www.googleapis.com/plus/v1/people/#{page_id}?key=#{google_api_key}").read    
obj = JSON.parse(data)

puts obj['plusOneCount'].to_i

但是，我不断收到此错误：

/Users/xng/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/open-uri.rb:346:in `open_http': 403 Forbidden (OpenURI::HTTPError)
    from /Users/xng/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/open-uri.rb:769:in `buffer_open'
    from /Users/xng/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/open-uri.rb:203:in `block in open_loop'
    from /Users/xng/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/open-uri.rb:201:in `catch'
    from /Users/xng/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/open-uri.rb:201:in `open_loop'
    from /Users/xng/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/open-uri.rb:146:in `open_uri'
    from /Users/xng/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/open-uri.rb:671:in `open'
    from /Users/xng/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/open-uri.rb:33:in `open'
    from gplus.rb:8:in `<main>'

我不确定这里有什么问题，任何帮助都将是很大的。