JAVA DOM API to read xml

[munch Chaudhary]

I am using java DOM api to read XML file entries. my class code is :
package com.ppi.security.module;
 
import java.io.File;
import java.util.*;
 
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
 
public class URLMapper {
 
 public String xmlReader(String reqUrl) {
  String requestedUrl = reqUrl;
  String requestedTarget = "";
  String strUrl= ""; 
  String strTarget = "";
  try {
  File file = new File("\\jboss-4.0.3SP1\\properties\\chat-demo\\TargetMapper.xml");
  //File file = new File("E:\\WEB-INF\\web.xml");
  Map<String, String> targetMap = new HashMap<String , String>();
  DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
  DocumentBuilder db = dbf.newDocumentBuilder();
  Document doc = db.parse(file);

  doc.getDocumentElement().normalize();
  System.out.println("Root element " + doc.getDocumentElement().getNodeName());
  NodeList nodeLst = doc.getElementsByTagName("pair");
  System.out.println("Information of all pairs");
  
  // read the xml file and put all url-target pairs in Map targetMap.
  for (int s = 0; s < nodeLst.getLength(); s++) {

    Node fstNode = nodeLst.item(s);
    
    if (fstNode.getNodeType() == Node.ELEMENT_NODE) {
  
      Element fstElmnt = (Element) fstNode;
      NodeList urlElmntLst = fstElmnt.getElementsByTagName("url");
      Element urlElmnt = (Element) urlElmntLst.item(0);
      NodeList url = urlElmnt.getChildNodes();
      strUrl = ((Node) url.item(0)).getNodeValue();
      System.out.println("url  : "  + ((Node) url.item(0)).getNodeValue());
      
      NodeList targetElmntLst = fstElmnt.getElementsByTagName("target");
      Element targetElmnt = (Element) targetElmntLst.item(0);
      NodeList target = targetElmnt.getChildNodes();
      strTarget= ((Node) target.item(0)).getNodeValue();
      System.out.println("target  : " + ((Node) target.item(0)).getNodeValue());
      
      targetMap.put(strUrl, strTarget);
    }

  }
  
  // fetch target corresponding to the requested URL from the targetMap.
  if (targetMap.containsKey(requestedUrl)){
  requestedTarget = targetMap.get(requestedUrl);
  System.out.println(">>>>>>>>>>>>> targetMap contains the requested url");
  System.out.println("requestedUrl is >> "+ requestedUrl);
  System.out.println("requestedTarget is >> "+ requestedTarget);
  }
  } catch (Exception e) {
  e.printStackTrace();
  }
  return requestedTarget;
 }
} 

Using above class I can't read my web.xml which contains following line:

 <!DOCTYPE web-app PUBLIC '-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN' 'http://java.sun.com/j2ee/dtds/web-app_2_2.dtd'> 

Removing this line make my xmlReader read the web.xml entries also.

I know it has smthing to do with the dtd but not sure in what direction to proceed for looking out a solution.

help needed regarding what is the issue here in what could be possible solutions.

[Yves Zoundi]

Try using a custom EntityResolver to resolve the DTD

http://java.sun.com/j2ee/dtds/web-app_2_2.dtd

Or disable validation in your DocumentBuilderFactory

[Anthony Castillon]

Hi. Why don't you try using XPath to traverse your XML? JDK 1.5 already has an XPath interface which will allow you to use an XPath expression to jump to a node and work with it. I used it to parse XML files and it was pretty fast (well, until the XML file got really big and I had to switch to StAX).

Hope this helps.
Anthony

[Anthony Castillon]

Hi. Why don't you try using XPath to traverse your XML? JDK 1.5 already has an XPath interface which will allow you to use an XPath expression to jump to a node and work with it. I used it to parse XML files and it was pretty fast (well, until the XML file got really big and I had to switch to StAX).

Hope this helps.
Anthony

[Jelle Klap]

Originally posted by Anthony Castillon:
Hi. Why don't you try using XPath to traverse your XML? JDK 1.5 already has an XPath interface which will allow you to use an XPath expression to jump to a node and work with it. I used it to parse XML files and it was pretty fast (well, until the XML file got really big and I had to switch to StAX).

Hope this helps.
Anthony

For large document processing I've recently been introduced to DataDirect XQuery, which offers an XQJ implementation based on the JSR-255 proposed final draft. It offers stream-based processing of large XML documents using StAX (Woodstox I believe). Coupled with document projection techniques it does a pretty good job of keeping the memory footprint as small as possible. I've really taken a liking to the XQuery approach of processing XML. Unfortunately the DataDirect implementation is fully commercial, so I'm still on the look-out for a solid freeware (preferably open-source) alternative, for use in my private little developement projects