How to access element attributes using JSP and XML?

[nathj]

Hi,

I'm trying to develop what should be a simple jsp that reads an XML file, parses it and displays the content in a web page. Simple right?

I have developed the XML and so any changes can be made there.

The XML IS

<?xml version="1.0" encoding="UTF-8"?>
<featured>
	<module type="Course Tool" title="Video Loader">
		<description>Do you want to deliver high quality vidoe to your class? This tool will enable you to load video content quickly and easily.</description>
		<img></img>
	</module>
	<module type="Course Tool" title="Content Block Loader">
		<description>Class content is more engaging when it is beautifully presented - use this tool to easily present the information in the most appealing manner possible.</description>
		<img></img>
	</module>
	<module type="Module" title="Art Gallery" priority="1">
		<description>Showcasing the best student artwork from across the foundation.</description>
		<img></img>
	</module>
	<module type="Module" title="Open Source">
		<description>Details on software that is free to use. Categorised to help you find the best application available.</description>
		<img></img>
	</module>
</featured>

The JSP that reads this uses a little Java class so here they are:

Java Class

package org.esf.utils;

import java.io.File;

import javax.servlet.jsp.JspWriter;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import javax.xml.parsers.*;
import org.w3c.dom.*;

public class EsfDomParserBean implements java.io.Serializable
{
	public EsfDomParserBean()
	{
	}

	public static Document getDocument(String file) throws Exception
	{

		// Step 1: create a DocumentBuilderFactory
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

		// Step 2: create a DocumentBuilder
		DocumentBuilder db = dbf.newDocumentBuilder();

		// Step 3: parse the input file to get a Document object
		Document doc = db.parse(new File(file));
		return doc;
	}
}

The JSP

<div class="horizontalScroll" id="horizontalScroll" style="display:block;float:left;overflow:auto;overflow-x:scroll;overflow-y:hidden;height:250px">
	<%
		String esfXMLPath = blackboard.platform.plugin.PlugInUtil.getUri("ESFN", "Featured-Module", "FeaturedModule.xml");
		Document doc = EsfDomParserBean.getDocument(esfXMLPath);
		traverseTree(doc, out);
	%>

	<%!private void traverseTree(Node node, JspWriter out) throws Exception 
		{
			if (node == null) 
			{
				return;
			}
			int type = node.getNodeType();
			String itemTitle = "";
			switch (type) 
			{
				// handle document nodes
				case Node.DOCUMENT_NODE: 
				{
					out.println("<div class=\"detailsContainer\" id=\"detailsContainer\" style=\"display:inline-block;float:left;\">");
					traverseTree(((Document) node).getDocumentElement(), out);
					break;
				}
				// handle element nodes
				case Node.ELEMENT_NODE: 
				{
					String elementName = node.getNodeName();
					
					if (elementName.equalsIgnoreCase("module")) 
					{
						Element e = (Element) node;
						if(e.hasAttribute("type") && e.hasAttribute("title"))
						{
							itemTitle = "<h3>" + e.getAttribute("type") + " " + e.getAttribute("title") + "</h3>";
						}
						else
						{
							itemTitle = "<h3>Cannot find type or title</h3>";
						}
						out.println("</div><div class=\"detailsContainer\" id=\"detailsContainer\" style=\"display:inline-block;float:left;\">");
					}
					NodeList childNodes = node.getChildNodes();
					if (childNodes != null) 
					{
						int length = childNodes.getLength();
						for (int loopIndex = 0; loopIndex < length; loopIndex++) 
						{
							traverseTree(childNodes.item(loopIndex), out);
						}
					}
					break;
				}
				// handle text nodes
				case Node.TEXT_NODE: 
				{
					String data = node.getNodeValue().trim();
					if ((data.indexOf("\n") < 0) && (data.length() > 0)) 
					{
						if(data.toUpperCase().contains(".jpg")||data.toUpperCase().contains(".jpeg")||data.toUpperCase().contains(".png"))
						{
							out.println("<span class=\"rightContainer\" id=\"rightContainer\" style=\"display:inline;float:right\"><img src=\"" + data + "\"/></span>");
						}
						else
						{
							
							out.println("<span class=\"leftContainer\" id=\"leftContainer\" style=\"display:inline;float:left\">" + itemTitle +  data + "</span>");
						}
					}
				}
			}
		}
%>
</div>

I need to get the type and title attributes out of the module element so that I can write them out in a <h3> tags inside the leftContainer span. The trouble is I can't find the way to retrieve this information. I've been reading around the web for a couple of days now and I'm not finding anything on this.

Does anyone have a great tip/pointer for me or even a tutorial where this has been done already?

Cheers
nathj

[nathj]

Hi,

Here's a quick update on the progress I'm making. As such the question has changed slightly now.

<%
	String esfXMLPath = blackboard.platform.plugin.PlugInUtil.getUri("ESFN", "Featured-Module", "FeaturedModule.xml");
	Document doc = EsfDomParserBean.getDocument(esfXMLPath);
	//traverseTree(doc, out);
	Element root = doc.getDocumentElement();
	NodeList moduleList = root.getChildNodes();
	
	StringBuilder output = new StringBuilder("<div class=\"horizontalScroll\" id=\"horizontalScroll\" style=\"display:block;float:left;overflow:auto;overflow-x:scroll;overflow-y:hidden;height:250px\">");
	
	for(int i = 0; i < moduleList.getLength(); i++)
	{
		Node module = moduleList.item(i);
		if(module.getNodeName().equals("module"))
		{
			output.append("<div class=\"detailsContainer\" id=\"detailsContainer\" style=\"display:inline-block;float:left;\">");
			Element section = (Element) moduleList.item(i);
			String title= "<h3>" + section.getAttribute("type") + "&nbsp;&mdash;&nbsp;" + section.getAttribute("title") + "</h3>";
			
			NodeList moduleDetails = module.getChildNodes();
			for(int j = 0; j < moduleDetails.getLength(); j++)
			{
				Node moduleDetail = moduleDetails.item(j);
				if(moduleDetail.getNodeName().equalsIgnoreCase("description"))
				{
					output.append("<span class=\"leftContainer\" id=\"leftContainer\" style=\"display:inline;float:left\">" + title + moduleDetail.getNodeValue() + "</span>");
				}
				if(moduleDetail.getNodeName().equalsIgnoreCase("img"))
				{
					output.append("<span class=\"rightContainer\" id=\"rightContainer\" style=\"display:inline;float:right\"><img src=\"" + moduleDetail.getNodeValue() + "\"/></span>");
				}
			}
			output.append("</div>");
		}
	}
	output.append("</div>");
%>
<%=output.toString() %>

Now I'm getting the type and title out of the module element which is great. The trouble is that I now am not getting the data out of the XML, so I'm not seeing the description coming out.

Any help on this is greatly appreciated.

Cheers
nathj

[nathj]

Hi,

A little bit of perseverance and some playing around I have it cracked.

<%
	String esfXMLPath = blackboard.platform.plugin.PlugInUtil.getUri("ESFN", "Featured-Module", "FeaturedModule.xml");
	Document doc = EsfDomParserBean.getDocument(esfXMLPath);
	//traverseTree(doc, out);
	Element root = doc.getDocumentElement();
	NodeList moduleList = root.getChildNodes();
	
	StringBuilder output = new StringBuilder("<div class=\"horizontalScroll\" id=\"horizontalScroll\" style=\"display:block;float:left;overflow:auto;overflow-x:scroll;overflow-y:hidden;height:250px\">");
	
	for(int i = 0; i < moduleList.getLength(); i++)
	{
		Node module = moduleList.item(i);
		if(module.getNodeName().equals("module"))
		{
			output.append("<div class=\"detailsContainer\" id=\"detailsContainer\" style=\"display:inline-block;float:left;\">");
			Element section = (Element) moduleList.item(i);
			String title= "<h3>" + section.getAttribute("type") + "&nbsp;&mdash;&nbsp;" + section.getAttribute("title") + "</h3>";
			
			NodeList moduleDetails = module.getChildNodes();
			for(int j = 0; j < moduleDetails.getLength(); j++)
			{
				Node moduleDetail = moduleDetails.item(j);
				if(moduleDetail.getNodeName().equalsIgnoreCase("description"))
				{
					output.append("<span class=\"leftContainer\" id=\"leftContainer\" style=\"display:inline;float:left\">" + title + "<p>" + moduleDetail.getChildNodes().item(0).getNodeValue() + "</p></span>");
				}
				if(moduleDetail.getNodeName().equalsIgnoreCase("img"))
				{
					output.append("<span class=\"rightContainer\" id=\"rightContainer\" style=\"display:inline;float:right\"><img src=\"" + moduleDetail.getChildNodes().item(0).getNodeValue() + "\"/></span>");
				}
			}
			output.append("</div>");
		}
	}
	output.append("</div>");
%>
<%=output.toString() %>

I admit I need some error trapping in here - particularly to cater for NullPointerExce ptions but the basics are there thanks to :

http://groups.google.com/group/Google-Web-Toolkit/browse_thread/thread/ece93ba9d9b39322?pli=1

http://www.java2s.com/Code/JavaAPI/org.w3c.dom/NodegetNodeValue.htm

Thanks
nathj