rack分享（一）：rack、rackbuilder和rackup

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Rack app的定义方式是：

 

require ‘rack’
class MyServer
  def call(env)
    [200, {}, ['hello world']]
  end
end
Rack::Handler::WEBrick.run MyServer.new, Port: 2000

 要给app加一些中间件，就需要这么写：

app = MyServer.new
app = Rack::Lint.new(app)
app = Rack::ShowStatus.new(app)
app = Rack::ShowExceptions.new(app)
app = Rack::CommonLogger.new(app)

Rack有自己的DSL（领域内专属语言）叫Rack::Builder，定义方法是：

 

 

app = Rack::Builder.new do
  use Rack::CommonLogger
  use Rack::ShowExceptions
  use Rack::ShowStatus
  use Rack::Lint
  run MyServer.new
end

 也可以把DSL的代码写在单独的ru配置文件中，这种方式形成的文件叫rackup文件：

 

 

#!/usr/bin/env rackup
use Rack::CommonLogger
use Rack::ShowExceptions
use Rack::ShowStatus
use Rack::Lint
run MyServer.new

 执行myserver.ru -s webrick -p 2000