Start the appengine-tools gem

lib/appengine-tools/web-xml.rb

 #!/usr/bin/ruby1.8 -w
 #
 # Copyright:: Copyright 2009 Google Inc.
 # Original Author:: Ryan Brown (mailto:ribrdb@google.com)
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #      http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
 require 'rubygems'
 require 'rack'
 require 'rexml/document'
-require 'rexml/formatters/pretty'
 
 class WebXmlBuilder < Rack::Builder
   DUMMY_APP = Proc.new{|env|}
   
   def initialize(&block)
     @path = "/"
     @paths = Hash.new {|h, k| h[k] = []}
     instance_eval(&block) if block_given?
   end
   
@@ skipping 14 matching lines @@
       ensure
         @path = saved_path
       end
     end
   end
   
   def run(app)
     @paths[@path] << [app, [], nil]
   end
 
-  def write
+  def to_xml
     xml = REXML::Document.new.add_element('web-app')

[woodie, 2009/07/03 00:59:21]

It may be more appropriate to use doc

doc = REXML::Document...

     xml.add_attribute("xmlns", "http://java.sun.com/xml/ns/javaee")
     xml.add_attribute("version", "2.5")
     each_path do |path, objects|
       pattern = path + "*"
       objects.each do |object, args, block|
         if object.respond_to? :to_xml
           object.to_xml(pattern, xml, *args, &block)
         end
       end
     end
-    Dir.mkdir('WEB-INF') unless File.exists?('WEB-INF')
-    open('WEB-INF/web.xml', 'w') do |out|
-      fmt = REXML::Formatters::Pretty.new
-      fmt.compact = true
-      fmt.write(xml, out)
-    end
+    xml
   end
   
 private
 
   def each_path
     @paths.sort {|a, b| b[0].length - a[0].length}.each do |path, value|
       yield path, value
     end
   end
 end
 
 class JavaServlet
   def initialize(klass, name=nil)
     @klass = klass.to_s
     @name = (name || klass).to_s
   end
   
   def call(env)
     raise RuntimeError, "JavaServlet should be dispatched by web.xml"
   end
   
   def to_xml(pattern, xml)
-    srv = REXML::Element.new('servlet')
-    srv.add_element('servlet-name').add_text(@name)
-    srv.add_element('servlet-class').add_text(@klass)
-    xml.add_element(srv)
-    map = REXML::Element.new('servlet-mapping')
+    servlet = xml.add_element('servlet')
+    servlet.add_element('servlet-name').add_text(@name)
+    servlet.add_element('servlet-class').add_text(@klass)
+    map = xml.add_elemtn('servlet-mapping')
     map.add_element('servlet-name').add_text(@name)
     map.add_element('url-pattern').add_text(pattern.to_s)
-    xml.add_element(map)
   end
 end
 
 class JavaServletFilter
   def self.to_xml(pattern, xml, klass, name=nil)
     name ||= klass
-    srv = REXML::Element.new('servlet')
-    srv.add_element('filter-name').add_text(name.to_s)
-    srv.add_element('filter-class').add_text(klass.to_s)
-    xml.add_element(srv)
-    map = REXML::Element.new('filter-mapping')
+    filter = xml.add_element('filter')
+    filter.add_element('filter-name').add_text(name.to_s)
+    filter.add_element('filter-class').add_text(klass.to_s)
+    map = xml.add_element('filter-mapping')
     map.add_element('filter-name').add_text(name.to_s)
     map.add_element('url-pattern').add_text(pattern.to_s)
-    xml.add_element(map)
   end
   
   def self.new(app, *args, &block)
     app
   end
 end
 
 class JavaContextListener
   def self.to_xml(pattern, xml, klass)
-    lsn = REXML::Element.new('listener')
-    lsn.add_element('listener-class').add_text(klass.to_s)
-    xml.add_element(lsn)
+    listener = xml.add_element('listener')
+    listener.add_element('listener-class').add_text(klass.to_s)
   end
   
   def self.new(app, *args, &block)
     app
   end
 end
 
 class JavaContextParams
   def self.to_xml(pattern, xml, params)
     params.each do |name, value|
-      cxt = REXML::Element.new('context-param')
-      ctx.add_element('param-name').add_text(name.to_s)
-      ctx.add_element('param-value').add_text(value.to_s)
-      xml.add_element(ctx)
+      e = xml.add_element('context-param')
+      e.add_element('param-name').add_text(name.to_s)
+      e.add_element('param-value').add_text(value.to_s)
     end
   end
   
   def self.new(app, *args, &block)
     app
   end
 end