DOM 解析器
让我们先来解析 XML 数据，首先我们先引入 rexml/document 库，通常我们可以将 REXML 在顶级的命名空间中引入：
#!/usr/bin/ruby -w
require 'rexml/document'
include REXML
xmlfile = File.new("movies.xml")
xmldoc = Document.new(xmlfile)
# 获取 root 元素
root = xmldoc.root
puts "Root element : " + root.attributes["shelf"]
# 以下将输出电影标题
xmldoc.elements.each("collection/movie"){
|e| puts "Movie Title : " + e.attributes["title"]
}
# 以下将输出所有电影类型
xmldoc.elements.each("collection/movie/type") {
|e| puts "Movie Type : " + e.text
}
# 以下将输出所有电影描述
xmldoc.elements.each("collection/movie/description") {
|e| puts "Movie Description : " + e.text
}
以上实例输出结果为：
Root element : New Arrivals Movie Title : Enemy Behind Movie Title : Transformers Movie Title : Trigun Movie Title : Ishtar Movie Type : War, Thriller Movie Type : Anime, Science Fiction Movie Type : Anime, Action Movie Type : Comedy Movie Description : Talk about a US-Japan war Movie Description : A schientific fiction Movie Description : Vash the Stampede! Movie Description : Viewable boredom SAX-like Parsing:
SAX 解析器
处理相同的数据文件：movies.xml，不建议SAX的解析为一个小文件，以下是个简单的实例：
#!/usr/bin/ruby -w
require 'rexml/document'
require 'rexml/streamlistener'
include REXML
class MyListener
include REXML::StreamListener
def tag_start(*args)
puts "tag_start: #{args.map {|x| x.inspect}.join(', ')}"
end
def text(data)
return if data =~ /^w*$/ # whitespace only
abbrev = data[0..40] + (data.length > 40 ? "..." : "")
puts " text : #{abbrev.inspect}"
end
end
list = MyListener.new
xmlfile = File.new("movies.xml")
Document.parse_stream(xmlfile, list)
以上输出结果为：
tag_start: "collection", {"shelf"=>"New Arrivals"}
tag_start: "movie", {"title"=>"Enemy Behind"}
tag_start: "type", {}
text : "War, Thriller"
tag_start: "format", {}
tag_start: "year", {}
tag_start: "rating", {}
tag_start: "stars", {}
tag_start: "description", {}
text : "Talk about a US-Japan war"
tag_start: "movie", {"title"=>"Transformers"}
tag_start: "type", {}
text : "Anime, Science Fiction"
tag_start: "format", {}
tag_start: "year", {}
tag_start: "rating", {}
tag_start: "stars", {}
tag_start: "description", {}
text : "A schientific fiction"
tag_start: "movie", {"title"=>"Trigun"}
tag_start: "type", {}
text : "Anime, Action"
tag_start: "format", {}
tag_start: "episodes", {}
tag_start: "rating", {}
tag_start: "stars", {}
tag_start: "description", {}
text : "Vash the Stampede!"
tag_start: "movie", {"title"=>"Ishtar"}
tag_start: "type", {}
tag_start: "format", {}
tag_start: "rating", {}
tag_start: "stars", {}
tag_start: "description", {}
text : "Viewable boredom"
