在使用Ruby获取正文之前，如何检查Content-type标头？

result = http_client.get(\'/some_page.html\') do |response|
  if response.content_type == \'text/html\' and response.code == 200
    response.read_body #the headers are returned along with page body
  else
    #not reading the body so only the headers are returned without body
  end
end

p result.code #>200
p result.content_type #>text/html
p result.body #><DOCTYPE html...

p result.code #>404
p result.content_type #>text/html
p result.body #>nil

client.request_get(uri.request_uri) do |res|
  if res.content_type == \'text/html\'
    res.read_body
  else
    res.instance_eval {@body_exist = false}
  end
end