Xpath question about NodeSet .contains() function

[Wei Cheng <We...@baylor.edu>]

Hi All,
 I have tried to use Xalan package to do my master's project.
 First, I write a primary key fuction to try to test whether XMl
 document can satisfy the primary key requirement.
 I modify the example ApplyXpath.java and foo.xml to test my idea.
 I use foo1.xml as an XMl document input.
<?xml version="1.0"?>
<doc>
  <name>
    <firstname> David </firstname>
    <lastname> Marston</lastname>
  </name>
  <name>
    <firstname> David  </firstname>
    <lastname> Bertoni </lastname>
  </name>
  <name>
    <firstname> Donald  </firstname>
    <lastname> Leslie </lastname>
  </name>
   <name>
    <firstname> Emily  </firstname>
    <lastname> Farmer </lastname>
  </name>
   <name>
    <firstname> Jack  </firstname>
    <lastname> Donohue</lastname>
  </name>
   <name>
    <firstname> Myriam  </firstname>
    <lastname> Midy</lastname>
  </name>
   <name>
    <firstname> Paul </firstname>
    <lastname> Dick</lastname>
  </name>
   <name>
    <firstname> Robert </firstname>
    <lastname> Weir</lastname>
  </name>
  <name>
    <firstname> Scott </firstname>
    <lastname> Boag</lastname>
  </name>
   <name>
    <firstname> Shane </firstname>
    <lastname> Curcuru</lastname>
  </name>
</doc>
and I change ApplyXPath.java to MyXpath.java
// This file uses 4 space indents, no tabs.

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import org.apache.xerces.parsers.DOMParser;
import org.apache.xpath.XPathAPI;
//import org.apache.xpath.xml.FormatterToXML;
import org.apache.xalan.utils.TreeWalker;
import org.apache.xalan.utils.DOMBuilder;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.DocumentFragment;
import org.w3c.dom.Node;
import org.apache.xpath.NodeSet; //import NodeSet
import org.apache.xalan.lib.Extensions; // import Extensions for NodeSet
import org.w3c.dom.NodeList;
import org.w3c.dom.traversal.NodeIterator;
//import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
import org.xml.sax.InputSource;

// Imported JAVA API for XML Parsing 1.0 classes
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

// Imported Serializer classes
import org.apache.serialize.OutputFormat;
import org.apache.serialize.Serializer;
import org.apache.serialize.SerializerFactory;
import org.apache.xml.serialize.transition.XMLSerializer;
import org.apache.xml.serialize.transition.TextSerializer;

/**
 *  Very basic utility for applying an XPath epxression to an xml file and printing information
/  about the execution of the XPath object and the nodes it finds.
 *  Takes 1 argument:
 *     (1) an xml filename
 *  Examples:
 *     java MyXPath foo1.xml /
 */
public class MyXPath
{
    protected String filename = null;
    protected String xpath = "/doc/name/firstname";
    //suppose firname is a primary key attribute
    Document doc = null;
    Element root = null;
    String part1=null;
    String part2=null;
    /** Process input args and execute the XPath.  */
    public void getDocument(String[] args)
    {
        filename = args[0];
        if (filename != null)
        {
            InputSource in;
            try
            {
                in = new InputSource(new FileInputStream(filename));
            }
            catch (FileNotFoundException fnf)
            {
                System.err.println("FileInputStream of " + filename + " threw: " + fnf.toString());
                fnf.printStackTrace();
                return;
            }

            try
            {
                DocumentBuilderFactory dfactory = DocumentBuilderFactory.newInstance();
                DocumentBuilder docBuilder = dfactory.newDocumentBuilder();
                doc = docBuilder.parse(in);
                root = doc.getDocumentElement();
            }
            catch (ParserConfigurationException pce)
            {
                pce.printStackTrace();
            }
            catch(Exception e1)
            {
                System.err.println("Parsing " + filename + " threw: " + e1.toString());
                e1.printStackTrace();
                return;
            }
        }
    }
    public boolean primarykey()
    {
        System.out.println(xpath);
         NodeIterator ni1 = null;
        try
        {
            // Use the simple XPath API to select a nodeIterator.
            ni1 = XPathAPI.selectNodeIterator(doc, xpath);
        }
        catch (Exception e2)
        {
            System.err.println("selectNodeIterator threw: " + e2.toString() + " perhaps your xpath didn't select any nodes");
            e2.printStackTrace();
            return false;
        }
        NodeSet ns1=new NodeSet(ni1); // change from nodeiterator to nodeset
         Node n=ns1.item(0);
          String x2=new String("/doc/name[1]/following-sibling::name/firstname");
          //get the following-sibling of the name[1]
            NodeIterator ni2 = null;
            try
            {
                // Use the simple XPath API to select a nodeIterator.
                ni2 = XPathAPI.selectNodeIterator(doc, x2);
            }
            catch (Exception e2)
            {
                System.err.println("selectNodeIterator threw: " + e2.toString() + " perhaps your xpath didn't select any nodes");
                e2.printStackTrace();
                return false;
            }
            NodeSet ns2=new NodeSet(ni2); // change from nodeiterator to nodeset
            if (ns2.contains(n))    // in my case because the name[2]
            //firstname is the same as name[1], so has duplicate node
            // "David" for firstname  but cann't find duplicate node
             {
              System.out.println("dupicate node found");
             return false;
        }          
        return true;

    }
    /** Main method to run from the command line.    */
    public static void main (String[] args)
    {
        if (args.length != 1)
        {
            System.out.println("java MyXPath filename.xml \n"
            + "Reads filename.xml ");
            return;
        }
        MyXPath app = new MyXPath();
        app.getDocument(args);
        if (app.primarykey())
          System.out.println("is a primary key");
        else 
          System.out.println("is not a primary key");
    }

} // end of class MyXPath

 When I tried to test this program, I always get the answer "is a
 primary key", I don't know how to realize contains function.
 hopefully somebody can give me a help.
  

Best regards,
 Wei                          mailto:Wei_Cheng@baylor.edu