bookpriceservlet.java

java web services how to program

// Fig. 15.9: BookPriceServlet.java.
// Class BookPriceServlet exposes the Book Price Web Service for
// Bookstore 1.
package jws1casestudy.bookstore1;

// Java core packages
import java.sql.*;
import java.util.*;

// Java extension packages
import javax.servlet.*;
import javax.xml.messaging.*;
import javax.xml.soap.*;

// Deitel packages
import jws1casestudy.pricefinder.common.*;

public class BookPriceServlet extends JAXMServlet 
   implements ReqRespListener {

   // factory used to create SOAPMessage objects
   private MessageFactory messageFactory;

   // reference to object that provides Web-Service
   private BookPrice service;

   // initialize BookPriceServlet
   public void init( ServletConfig config ) 
      throws ServletException
   {
      super.init( config );

      // instantiate Web-service object and obtain MessageFactory
      try {
         service = new BookPriceImpl();
         messageFactory = MessageFactory.newInstance();
      }

      // handle exception in creating MessageFactory
      catch ( Exception exception ) {
         exception.printStackTrace();
      }

   } // end method init

   // container invokes this method upon receiving SOAP message
   public SOAPMessage onMessage( SOAPMessage message )
   {
      // invoke Web service and return results as SOAP message
      try {

         // extract ISBN from incoming SOAPMessage
         String isbn = getISBN( message );

         // invoke Book Price Web service
         if ( service != null && isbn != null ) {
            PriceQuote priceQuote = service.getPrice( isbn );

            // store result as SOAP message and return to client
            if ( priceQuote != null )
               return createResponse( priceQuote );
         }
      }

      // handle exception if unable to create SOAP message
      catch ( Exception exception ) {
         exception.printStackTrace();
      }

      return null;

   } // end method onMessage

   // extract ISBN from SOAP message request
   private String getISBN( SOAPMessage message ) 
      throws SOAPException
   {
      // obtain references to envelope and body of message
      SOAPPart part = message.getSOAPPart();
      SOAPEnvelope envelope = part.getEnvelope();
      SOAPBody body = envelope.getBody();

      // get child elements of SOAPBody
	  Iterator childElements = body.getChildElements();

	  childElements.next(); // skip first element

      // cast to SOAPBodyElement
	  SOAPBodyElement getPriceElement = 
         ( SOAPBodyElement ) childElements.next();

      // get child elements of SOAPBodyElement
      Iterator subElements = getPriceElement.getChildElements();

	  subElements.next(); // skip first element

      // obtain SOAPElement that contains isbn
	  SOAPElement isbnElement = 
         ( SOAPElement ) subElements.next();
	  
      return isbnElement.getValue();

   } // end method getISBN

   // store PriceQuote as SOAP message
   private SOAPMessage createResponse( PriceQuote priceQuote )
      throws SOAPException
   {
      // create empty SOAP message
      SOAPMessage message = messageFactory.createMessage();

      // obtain references to response message elements
      SOAPPart part = message.getSOAPPart();
      SOAPEnvelope envelope = part.getEnvelope();
      SOAPBody body = envelope.getBody();

      // add namespace declarations
      envelope.addAttribute( envelope.createName( "xmlns:xsd" ), 
         "http://www.w3.org/2001/XMLSchema" );
      envelope.addAttribute( envelope.createName( "xmlns:ns1" ), 
         "http://www.deitel.com/BookPrice/type" );
      envelope.addAttribute( envelope.createName( "xmlns:xsi" ), 
         "http://www.w3.org/2001/XMLSchema-instance" );
      envelope.addAttribute( 
         envelope.createName( "xmlns:SOAP-ENC" ), 
         "http://schemas.xmlsoap.org/soap/encoding/" );

      // set encoding style for SOAP body
      body.setEncodingStyle( 
         "http://schemas.xmlsoap.org/soap/encoding/" );

      // create root element
      SOAPBodyElement returnMessageElement = body.addBodyElement( 
         envelope.createName( "getPriceResponse", 
            "ns2", "http://www.deitel.com/BookPrice.wsdl" ) );

      // create root element
      SOAPElement priceQuoteElement = 
         returnMessageElement.addChildElement( 
            envelope.createName( "return" ) );
      priceQuoteElement.addAttribute( 
         envelope.createName( "xsi:type" ), 
            "ns1:PriceQuote" );

      // store price element as priceQuoteElement child
      SOAPElement priceElement = 
         priceQuoteElement.addChildElement( 
            envelope.createName( "price" ) );
      priceElement.addTextNode(
         Double.toString( priceQuote.getPrice() ) );
      priceElement.addAttribute( 
         envelope.createName( "xsi:type" ), "xsd:double" );

      // store ISBN element as priceQuoteElement child
      SOAPElement isbnElement = 
         priceQuoteElement.addChildElement( 
            envelope.createName( "isbn" ) );
      isbnElement.addTextNode( priceQuote.getIsbn() );
      isbnElement.addAttribute( 
         envelope.createName( "xsi:type" ), "xsd:string" );

      // store storeID element as priceQuoteElement child
      SOAPElement storeIdElement = 
         priceQuoteElement.addChildElement( 
            envelope.createName( "storeID" ) );
      storeIdElement.addTextNode(
         Integer.toString( priceQuote.getStoreID() ) );
      storeIdElement.addAttribute(
         envelope.createName( "xsi:type" ), "xsd:int" );

      // store storeDescription element as priceQuoteElement child
      SOAPElement storeDescriptionElement = 
         priceQuoteElement.addChildElement( 
            envelope.createName( "storeDescription" ) );
      storeDescriptionElement.addTextNode(
         priceQuote.getStoreDescription() );
      storeDescriptionElement.addAttribute(
         envelope.createName( "xsi:type" ), "xsd:string" );

      return message;

   } // end method createResponse

} // end class BookPriceServlet