我最終創建了一個基於Builder和Strategy模式的解決方案。我使用Builder模式提取解析並將邏輯構建到自己的類中。這使我可以輕鬆地分別添加新的分析器和構建器。我使用Strategy模式來實現個人解析和構建邏輯,因爲這個邏輯取決於我的輸入和輸出格式。
下圖顯示了我的解決方案的UML圖。下面
![Parser/Builder Model](https://i.stack.imgur.com/esIWC.png)
的清單顯示我的Ruby實現。實現有點微不足道,因爲我構建的對象非常簡單。對於那些認爲這段代碼臃腫和Java-ish的人,我認爲這實際上是一個很好的設計。我承認,在這樣一個微不足道的案例中,我可以直接將構建方法構建到我的業務對象中。然而,我並不是在我的其他應用程序中構建水果,而是相當複雜的對象,因此分離解析,構建和業務邏輯似乎是一個好主意。
require 'nokogiri'
require 'json'
class Fruit
attr_accessor :name
attr_accessor :size
attr_accessor :color
def initialize(attrs = {})
self.name = attrs[:name]
self.size = attrs[:size]
self.color = attrs[:color]
end
def to_s
"#{size} #{color} #{name}"
end
end
class FruitBuilder
def self.build(opts = {}, &block)
builder = new(opts)
builder.instance_eval(&block)
builder.result
end
def self.delegate(method, target)
method = method.to_sym
target = target.to_sym
define_method(method) do |*attrs, &block|
send(target).send(method, *attrs, &block)
end
end
end
class FruitObjectBuilder < FruitBuilder
attr_reader :fruit
delegate :name=, :fruit
delegate :size=, :fruit
delegate :color=, :fruit
def initialize(opts = {})
@fruit = Fruit.new
end
def result
@fruit
end
end
class FruitXMLBuilder < FruitBuilder
attr_reader :document
def initialize(opts = {})
@document = Nokogiri::XML::Document.new
end
def name=(name)
add_text_node(root, 'name', name)
end
def size=(size)
add_text_node(root, 'size', size)
end
def color=(color)
add_text_node(root, 'color', color)
end
def result
document.to_s
end
private
def add_text_node(parent, name, content)
text = Nokogiri::XML::Text.new(content, document)
element = Nokogiri::XML::Element.new(name, document)
element.add_child(text)
parent.add_child(element)
end
def root
document.root ||= create_root
end
def create_root
document.add_child(Nokogiri::XML::Element.new('fruit', document))
end
end
class FruitJSONBuilder < FruitBuilder
attr_reader :fruit
def initialize(opts = {})
@fruit = Struct.new(:name, :size, :color).new
end
delegate :name=, :fruit
delegate :size=, :fruit
delegate :color=, :fruit
def result
Hash[*fruit.members.zip(fruit.values).flatten].to_json
end
end
class FruitParser
attr_reader :builder
def initialize(builder)
@builder = builder
end
def build(*attrs, &block)
builder.build(*attrs, &block)
end
end
class FruitObjectParser < FruitParser
def parse(other_fruit)
build do |fruit|
fruit.name = other_fruit.name
fruit.size = other_fruit.size
fruit.color = other_fruit.color
end
end
end
class FruitXMLParser < FruitParser
def parse(xml)
document = Nokogiri::XML(xml)
build do |fruit|
fruit.name = document.xpath('/fruit/name').first.text.strip
fruit.size = document.xpath('/fruit/size').first.text.strip
fruit.color = document.xpath('/fruit/color').first.text.strip
end
end
end
class FruitJSONParser < FruitParser
def parse(json)
attrs = JSON.parse(json)
build do |fruit|
fruit.name = attrs['name']
fruit.size = attrs['size']
fruit.color = attrs['color']
end
end
end
# -- Main program ----------------------------------------------------------
p = FruitJSONParser.new(FruitXMLBuilder)
puts p.parse('{"name":"Apple","size":"Big","color":"Red"}')
p = FruitXMLParser.new(FruitObjectBuilder)
puts p.parse('<fruit><name>Apple</name><size>Big</size><color>Red</color></fruit>')
p = FruitObjectParser.new(FruitJSONBuilder)
puts p.parse(Fruit.new(:name => 'Apple', :color => 'Red', :size => 'Big'))
來源
2011-07-18 17:07:43
t6d
好吧,我現在看看這個。也許,我找到了一些可以幫助我解決問題的靈感。然後,我會更新我的問題。非常感謝。 – t6d