如何在Ruby中使用eventmachine为HTTP服务器添加文件下载功能?
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?(filename) send_data "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? DevKit!
看来这就是我需要的。
出错的原因是安装eventmachine的时候,需要build tools,但系统中没有。出错信息中同时也给出了解决的法案:
(1) 到 http://rubyinstaller.org/downloads/ 去下载dev kit – DevKit-tdm-32-4.5.1-20101214-1400-sfx.exe
(2)按照 http://github.com/oneclick/rubyinstaller/wiki/Development-Kit/ 安装dev kit
主要安装步骤如下:
如果原来系统中已经安装了旧版的dev kit, 则删除它
下载上面提到的dev kit
解压下载下来的文件到指定的目录,如c:/devkit。(注意:目录不能有空格)
运行ruby dk.rb,然后按照提示分别运行ruby dk.rb init 和 ruby dk.rb install来增强ruby
可以运行
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
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