环境配置：

             先安装ruby,再安装builder

             builder安装方法： gem install builder

require 'builder'  

x = Builder::XmlMarkup.new(:target => $stdout, :indent => 1)
#":target =＞$stdout"参数：指示输出内容将被写向标准输出控制台
#":indent =＞1"参数：XML输出形式将被缩进一个空格字符x.instruct! :xml,:version =>'1.1',:encoding => 'gb2312'
x.comment! "书本信息"

x.library("shelf" => "Recent Acquisitions") {
x.section("name" => "ruby"){
x.book("isbn" => "0672310001"){
x.title "Programming Ruby" 
x.author "Yukihiro "
x.description "Programming Ruby - The Pragmatic Programmer's Guide"
}
}
}

p x   #打印XML

输出结果：

<?xml version="1.1" encoding="gb2312"?>
<!-- 书本信息 -->
<library shelf="Recent Acquisitions">
 <section name="ruby">
  <book isbn="0672310001">
   <title>Programming Ruby</title>
   <author>Yukihiro </author>
   <description>Programming Ruby - The Pragmatic Programmer's Guide</description>
  </book>
 </section>
</library>
<inspect/>
#<IO:0x2a06ae8>