1     安装ruby1.9.3

2     查看gem –v

3     查看ruby –v

4     gem update --system

5     gem install water

会提示ERROR:  Error installing watir:
        The 'ffi' 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'

6解决方案：

1、下载DevKit

   DevKit-tdm-32-4.5.2-20110712-1620-sfx.exe

2、解压DevKit

   解压到C:DevKit

3、安装并测试

     cd到解压目录下：

C:DevKit>ruby dk.rb init
[INFO] found RubyInstaller v1.9.3 at C:/Ruby193

Initialization complete! Please review and modify the auto-ge
'config.yml' file to ensure it contains the root directories
of the installed Rubies you want enhanced by the DevKit.

C:DevKit>ruby dk.rb install
[INFO] Updating convenience notice gem override for 'C:/Ruby1
[INFO] Installing 'C:/Ruby193/lib/ruby/site_ruby/devkit.rb'

C:DevKit>gem install rdiscount --platform=ruby
Fetching: rdiscount-1.6.8.gem ()
Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
Successfully installed rdiscount-1.6.8
1 gem installed
Installing ri documentation for rdiscount-1.6.8...
Installing RDoc documentation for rdiscount-1.6.8...