JRuby Xerces example

dom_parser_example.rb

gem 'nokogiri'

import java.lang.Integer
import java.lang.System

import java.io.IOException
import java.util.ArrayList
import java.util.Iterator
import java.util.List

import javax.xml.parsers.DocumentBuilder
import javax.xml.parsers.DocumentBuilderFactory
import javax.xml.parsers.ParserConfigurationException

import org.w3c.dom.Document
import org.w3c.dom.Element
import org.w3c.dom.NodeList
import org.xml.sax.SAXException

class DomParserExample
  def initialize
    @myEmpls = ArrayList.new
  end

  def runExample
    parseXmlFile
    parseDocument
    printData	
  end

  private

  def parseXmlFile
    dbf = DocumentBuilderFactory.newInstance

    begin
      db = dbf.newDocumentBuilder
      @dom = db.parse("employees.xml")
    rescue ParserConfigurationException => pce
      pce.printStackTrace
    rescue SAXException => se
      se.printStackTrace
    rescue IOException => ioe
      ioe.printStackTrace
    end
  end

  def parseDocument
    docEle = @dom.getDocumentElement
    nl = docEle.getElementsByTagName("Employee")
    if nl != nil && nl.getLength() > 0
      i = 0
      while i < nl.getLength()
        el = nl.item(i)
        e = getEmployee(el)
        @myEmpls.add(e)
         i+= 1
      end
    end
  end

  # I take an employee element and read the values in, create
  # an Employee object and return it
  # @param empEl
  # @return
  def getEmployee(empEl)
    name = getTextValue(empEl,"Name")
    id = getIntValue(empEl,"Id")
    age = getIntValue(empEl,"Age")
    type = empEl.getAttribute("type")
    e = {name: name,id: id, age: age, type: type}
    return e
  end

  # I take a xml element and the tag name, look for the tag and get
  # the text content 
  # i.e for <employee><name>John</name></employee> xml snippet if
  # the Element points to employee node and tagName is name I will return John  
  # @param ele
  # @param tagName
  # @return
  def getTextValue(ele, tagName)
    textVal = nil
    nl = ele.getElementsByTagName(tagName)
    if nl != nil && nl.getLength() > 0
      el = nl.item(0)
      textVal = el.getFirstChild().getNodeValue()
    end
    return textVal;
  end
    
  # Calls getTextValue and returns a int value
  # @param ele
  # @param tagName
  # @return
  def getIntValue(ele, tagName)
    return Integer.parseInt(getTextValue(ele,tagName))
  end
    
  # Iterate through the list and print the
  # content to console
  def printData
    System.out.println("No of Employees '" + @myEmpls.size.to_s + "'.")
    it = @myEmpls.iterator
    while it.hasNext
      System.out.println(it.next.to_s)
    end
  end
end

dpe = DomParserExample.new
dpe.runExample

employees.xml

<?xml version="1.0" encoding="UTF-8"?>
<Personnel>
  <Employee type='perma"nent'>
        <Name>Seagull</Name>
        <Id>3674</Id>
        <Age>34</Age>
   </Employee>
  <Employee type="contract">
        <Name>Robin</Name>
        <Id>3675</Id>
        <Age>25</Age>
    </Employee>
  <Employee type="permanent">
        <Name>Crow</Name>
        <Id>3676</Id>
        <Age>28</Age>
    </Employee>
</Personnel>