思路：
使用ruby eventmachine和em-http-server gem，完成一个简单的提供文件下载功能的HttpServer；
使用了EM的FileStreamer来异步发送文件，发送文件时先组装了header，然后调用FileStreamer。
代码：
require 'rubygems'
require 'eventmachine'
require 'em-http-server'
class HTTPHandler < EM::HttpServer::Server
attr_accessor :filename, :filesize, :path
def process_http_request
#send file async
if @http_request_method.to_s =~ /GET/ && @http_request_uri.to_s.end_with"HTTP/1.1 200 OK\n"
send_data "Server: XiaoMi\n"
send_data "Connection: Keep-Alive\n"
send_data "Keep-Alive: timeout=15\n"
send_data "Content-Type: application/octet-stream\n"
send_data "Content-Disposition: filename='#{filename}'\n"
send_data "Content-Length: #{filesize}\n"
send_data "\n"
streamer = EventMachine::FileStreamer.new(self, path)
streamer.callback {
# file was sent successfully
close_connection_after_writing
}
else
response = EM::DelegatedHttpResponse.new(self)
response.status = 200
response.content_type 'text/html'
response.content = "Package HttpServer<br>usage: wget http://host:port/#{filename}"
response.send_response
end
end
end
EM::run do
path = '/tmp/aaa.tar.gz'
EM::start_server("0.0.0.0", 8080, HTTPHandler) do |conn|
conn.filename = File.basename(path)
conn.filesize = File.size(path)
conn.path = path
end
end
PS：关于eventmachine安装错误的问题
在windows上安装 eventmachine 总是报错:
Building native extensions. This could take a while...
ERROR: Error installing eventmachine:
ERROR: Failed to build gem native extension.
或者另外一种:
ERROR: Error installing ruby-debug:
The 'linecache' native gem requires installed build tools.
Please update your PATH to include build tools or download the DevKit
from 'http://rubyinstaller.org/downloads' and follow the instructions
at 'http://github.com/oneclick/rubyinstaller/wiki/Development-Kit'
后来经过了漫长的Google,找到了2个solution:
1.用更低版本的eventmachine
这个提示一直不断，下面还有一大难错误，都是C的编译错误后来网上找了两个方法
（1）
gem install eventmachine-win32
这个貌似安装的是较低版本的
（2）gem install
eventmachine --pre
这个貌似安装的是 beta 1.0.0的。
2.升级devkit
看了一下，上面没有提具体的解决方案，但是给出了问题产生的两个可能原因：
（1）没有C编译环境
（2）路径当中有空格
看看上面的错误日志，发现可能就是编译环境的问题。于是找了一下。
我的ruby是用one-click installer装的，版本是1.8.6-p398。
在rubyinstaller的addon页面，找到了DevKit。
看了一下DevKit的说明：
//Sometimes you just want RubyGems to build that cool native,
//C-based extension without squawking.
//Who's your buddy"htmlcode">
gem install rdiscount –platform=ruby
来测试是否成功。
按照安装步骤，完成了DevKit的安装，非常简单。
然后，再次安装eventmachine：
gem install eventmachine