  1  import java.io.File;

  2  import java.io.IOException;

  3  import java.util.ArrayList;

  4  import javax.xml.parsers.DocumentBuilder;

  5  import javax.xml.parsers.DocumentBuilderFactory;

  6  import javax.xml.parsers.ParserConfigurationException;

  7  import javax.xml.xpath.XPath;

  8  import javax.xml.xpath.XPathExpressionException;

  9  import javax.xml.xpath.XPathFactory;

 10  import org.w3c.dom.Document;

 11  import org.xml.sax.SAXException;

 13  /**

 14     An XML parser for item lists

 15  */

 16  public class ItemListParser

 17  {

 18     private DocumentBuilder builder;

 19     private XPath path;

 21     /**

 22        Constructs a parser that can parse item lists.

 23     */

 24     public ItemListParser()

 25           throws ParserConfigurationException

 26     {

 27        DocumentBuilderFactory dbfactory

 28              = DocumentBuilderFactory.newInstance();

 29        builder = dbfactory.newDocumentBuilder();

 30        XPathFactory xpfactory = XPathFactory.newInstance();

 31        path = xpfactory.newXPath();

 32     }

 34     /**

 35        Parses an XML file containing an item list.

 36        @param fileName the name of the file

 37        @return an array list containing all items in the XML file

 38     */

 39     public ArrayList<LineItem> parse(String fileName)

 40        throws SAXException, IOException, XPathExpressionException

 41     {

 42        File f = new File(fileName);

 43        Document doc = builder.parse(f);

 45        ArrayList<LineItem> items = new ArrayList<LineItem>();

 46        int itemCount = Integer.parseInt(path.evaluate(

 47              "count(/items/item)", doc));

 48        for (int i = 1; i <= itemCount; i++)

 49        {

 50           String description = path.evaluate(

 51                 "/items/item[" + i + "]/product/description", doc);

 52           double price = Double.parseDouble(path.evaluate(

 53                 "/items/item[" + i + "]/product/price", doc));

 54           Product pr = new Product(description, price);

 55           int quantity = Integer.parseInt(path.evaluate(

 56                 "/items/item[" + i + "]/quantity", doc));

 57           LineItem it = new LineItem(pr, quantity);

 58           items.add(it);

 59        }

 60        return items;

 61     }

 62  }