Ruby 从不使用'；不包括分机

例如：

如果运行此命令：

require 'open-uri'
local_path = 'app/assets/images/'

image_url = 'https://www.gravatar.com/avatar/9784fd51f1db751e9806a0620f1c432b?s=32&d=identicon&r=PG'
image_name = image_url.match( /[&=-_\w:]+$/i ).to_s;
image_content = open(image_url).read.to_s
# image_extension = File.extname(image_content) # doesn't work


puts image_content

File.open( local_path + image_name + '.jpg' , 'wb') do |out_file|
    out_file.write(image_content)
end

图像已成功保存，但我必须对“.jpg”进行硬编码以连接到文件名的末尾（请查看最后一行，但只有两行）

---

目的是将

'.jpg'

替换为

图像_扩展

，使其仍能正常工作。

，也许吧。您看过

内容类型

标题了吗？@swan和很好的建议！

require "open-uri"
require "mime/types"

image_url = 'https://www.gravatar.com/avatar/9784fd51f1db751e9806a0620f1c432b?s=32&d=identicon&r=PG'
image_download = open(image_url)
type = MIME::Types[image_download.content_type]
extension = type[0].extensions[0]
# => "png"