streamparser.java

weblogic_src_xml.rar

package examples.xml.orderParser;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import weblogic.xml.stream.XMLInputStream;
import weblogic.xml.stream.XMLInputStreamFactory;
import weblogic.xml.stream.XMLEvent;
import weblogic.xml.stream.CharacterData;
import weblogic.xml.stream.StartElement;
import weblogic.xml.stream.XMLName;
import weblogic.xml.stream.XMLStreamException;
import weblogic.xml.stream.AttributeIterator;
import weblogic.xml.stream.Attribute;



/**
 * Demonstrates the parsing of an XML document into
 * business objects using the XMLInputStream API.
 *
 * @author Copyright (c) 2003 by BEA Systems, Inc. All Rights Reserved.
 */

public class StreamParser {

  private OrderBO orderBO = null;
  // Set to true for additional logging.
  private static final boolean DEBUG = false;

  public StreamParser() { }

  /**
  * <p>Creates a new XMLInputStream.</p>
  *
  * @param pName Name of XML document.
  * @return XMLInputStream
  * @exception XMLStreamException
  * @exception FileNotFoundException
  */
  public XMLInputStream getInputStream(String pName)
    throws XMLStreamException, FileNotFoundException
  {
    log("getInputStream");

    XMLInputStreamFactory factory = XMLInputStreamFactory.newInstance();
    return factory.newInputStream(new FileInputStream(pName));
  }

  /**
  * <p>Controls the flow of the XML document's overall parsing.</p>
  *
  * @param pStream XML input stream.
  * @exception Exception
  * @exception XMLStreamException
  */
  public void parse(XMLInputStream pStream)
    throws Exception, XMLStreamException
  {
    log("parse");

    // Go to the first start element of the stream.
    pStream.skip(XMLEvent.START_ELEMENT);

    // Get the current element and move to the next element.
    XMLEvent element = pStream.next();

    // Validate the name and element type.
    if (!element.getName().getLocalName().equals(OrderConstants.ORDER) && !element.isStartElement())
      throw new Exception("Cannot handle this doc");
    else {
      StartElement se = (StartElement)element;
      // Instantiate the order business object and set the order number.
      orderBO = new OrderBO();
      orderBO.setOrderNumber(getAttribute(se, OrderConstants.ORDER_NUMBER));
    }

    // Process the XML document looking for customer and item list elements.
    while(pStream.skip(XMLEvent.START_ELEMENT)) {
      XMLName name = pStream.peek().getName();
      if (name.getLocalName().equals(OrderConstants.CUSTOMER)) {
          processCustomer(pStream.getSubStream());
      } else if (name.getLocalName().equals(OrderConstants.ITEM_LIST)) {
          processItemList(pStream.getSubStream());
      } else {
         throw new Exception("Unknown XMLEvent "+name.getLocalName());
      }

      pStream.skipElement();
    }
  }

  /**
  * <p>Controls the flow of the customer parsing resulting
  *     in a customer business object.</p>
  *
  * @param pStream XML input stream.
  * @exception XMLStreamException
  */
  public void processCustomer(XMLInputStream pStream) throws XMLStreamException
  {
    log("processCustomer");

    // Instantiate and load the customer buiness object.
    // Iterate through the name and address elements
    // extracting known attributes to the customer business object.
    CustomerBO customerBO = new CustomerBO();
    pStream.skip();
    while(pStream.skip(XMLEvent.START_ELEMENT)) {
      StartElement se = (StartElement)pStream.peek();
      AttributeIterator attrs = (AttributeIterator)se.getAttributes();
      while (attrs.hasNext()) {
        Attribute attr = (Attribute)attrs.next();
        log(attr.getName().getLocalName()+"="+attr.getValue());
        if (attr.getName().getLocalName().equals(OrderConstants.FIRST_NAME))
          customerBO.setFirstName(attr.getValue());
        else if (attr.getName().getLocalName().equals(OrderConstants.LAST_NAME))
          customerBO.setLastName(attr.getValue());
        else if (attr.getName().getLocalName().equals(OrderConstants.STREET))
          customerBO.setStreet(attr.getValue());
        else if (attr.getName().getLocalName().equals(OrderConstants.CITY))
          customerBO.setCity(attr.getValue());
        else if (attr.getName().getLocalName().equals(OrderConstants.STATE))
          customerBO.setState(attr.getValue());
        else if (attr.getName().getLocalName().equals(OrderConstants.ZIP))
          customerBO.setZip(attr.getValue());
      }
      pStream.skip();
    }
    // Set the customer business object into the order business object.
    orderBO.setCustomer(customerBO);
  }

  /**
  * <p>Controls the flow of items in an item list element.</p>
  *
  * @param pStream XML input stream.
  * @exception XMLStreamException
  */
  public void processItemList(XMLInputStream pStream) throws XMLStreamException
  {
    log("processItemList");

    // Look for item start elements.
    // Pass stream for item processing.
    pStream.skip();
    while(pStream.skip(XMLEvent.START_ELEMENT)) {
      XMLName name = pStream.peek().getName();
      log("name="+name.getLocalName());
      if (name.getLocalName().equals(OrderConstants.ITEM))
          processItem(pStream.getSubStream());
      pStream.skip();
    }
  }

  /**
  * <p>Parses item data creating item business objects.</p>
  *
  * @param pStream XML input stream.
  * @exception XMLStreamException
  */
  public void processItem(XMLInputStream pStream) throws XMLStreamException
  {
    log("processItem");

    // Instantiate new item business object.
    ItemBO itemBO = new ItemBO();

    // Extract and load item number attribute.
    StartElement se = (StartElement)pStream.peek();
    itemBO.setItemNumber(getAttribute(se, OrderConstants.ITEM_NUMBER));

    // Extract known character data and load to item business object.
    pStream.skip();
    while(pStream.skip(XMLEvent.START_ELEMENT)) {
      XMLName name = pStream.peek().getName();
      if (name.getLocalName().equals(OrderConstants.DESCRIPTION)) {
        pStream.skip(XMLEvent.CHARACTER_DATA);
        CharacterData cd = (CharacterData)pStream.peek();
        if (cd.hasContent()) {
          log("content is "+cd.getContent());
          itemBO.setDescription(cd.getContent());
        }
      } else if (name.getLocalName().equals(OrderConstants.QUANTITY)) {
        pStream.skip(XMLEvent.CHARACTER_DATA);
        CharacterData cd = (CharacterData)pStream.peek();
        if (cd.hasContent()) {
          log("content is "+cd.getContent());
          itemBO.setQuantity(cd.getContent());
        }
      } else if (name.getLocalName().equals(OrderConstants.PRICE)) {
        pStream.skip(XMLEvent.CHARACTER_DATA);
        CharacterData cd = (CharacterData)pStream.peek();
        if (cd.hasContent()) {
          log("content is "+cd.getContent());
          itemBO.setPrice(cd.getContent());
        }
      }
      pStream.skip();
    }
    // Set the item business object into the order business object.
    orderBO.setItem(itemBO);
  }

  /**
  * <p>Extract known attribute value by name from a start element.</p>
  *
  * @param pStream XML input stream.
  * @return String Value of attribute.
  * @exception XMLStreamException
  */
  public String getAttribute(StartElement pStartElement, String pStr) throws XMLStreamException
  {
    log("getAttribute");

    String str = null;

    // Get value for known attribute name.
    AttributeIterator attrs = (AttributeIterator)pStartElement.getAttributes();
    if (attrs.hasNext()) {
      Attribute attr = (Attribute)attrs.next();
      log(attr.getName().getLocalName()+"="+attr.getValue());
      if (attr.getName().getLocalName().equals(pStr))
          str = attr.getValue();
    }
    return str;
  }

  /**
  * <p>Returns created order business object.</p>
  *
  * @return OrderBO
  */
  public OrderBO getOrderBO() { return orderBO; }

  // Utility logging.
  private void log(String pStr) { if (DEBUG) System.out.println(pStr); }
}