这是什么如果我想要简单的代码，我会这样做：

This is what I'd do if I want simple code:

require 'open-uri'
str = open('http://example.com')
str.content_type #=> "text/html"

最大的好处是重定向之后。

The big advantage is it follows redirects.

如果要检查一堆URL，您可能要在处理完之后在句柄上调用 close 找到了想要的东西。

If you're checking a bunch of URLs you might want to call close on the handles after you've found what you want.