booktitlesservlet.java

java web services how to program

// Fig. 11.4: BookTitlesServlet.java.
// Class BookTitlesServlet exposes the Book Titles Web service.
package com.deitel.jws1.jaxm.servlet;

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

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

// Deitel packages
import com.deitel.jws1.services.BookTitlesImpl;

public class BookTitlesServlet extends JAXMServlet 
   implements ReqRespListener {

   // factory used to create SOAPMessages
   private MessageFactory messageFactory;

   // reference to object that provides Web service
   private BookTitlesImpl service;

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

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

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

   } // end method init

   // container invokes this method upon receiving SOAP message
   public SOAPMessage onMessage( SOAPMessage soapMessage )
   {
      // invoke Web service and return results as SOAP message
      try {
         String bookTitles[] = null;

         // invoke Book Titles Web service to obtain titles
         if ( service != null )
            bookTitles = service.getBookTitles();

         // store results as SOAP message and return to client
         if ( bookTitles != null ) {

            // create empty SOAP message
            SOAPMessage message = messageFactory.createMessage();

            // obtain references to envelope and body of message
            SOAPPart soapPart = message.getSOAPPart();
            SOAPEnvelope soapEnvelope = soapPart.getEnvelope();
            SOAPBody soapBody = soapEnvelope.getBody();

            // create titles element to store book titles
            SOAPBodyElement titlesElement = 
               soapBody.addBodyElement( 
                  soapEnvelope.createName( "titles" ) );

            // store number of book titles as attribute
            titlesElement.addAttribute( 
               soapEnvelope.createName( "bookCount" ),
                  Integer.toString( bookTitles.length ) );

            // store each book title in title element
            for ( int i = 0; i < bookTitles.length; i++ )
               titlesElement.addChildElement( 
                  soapEnvelope.createName( 
                     "title" ) ).addTextNode( bookTitles[ i ] );

            return message;
         }
         else
            return null;
      }

      // handle exception if unable to create SOAP message
      catch ( SOAPException soapException ) {
         return null;
      }

   } // end method onMessage

} // end class BookTitlesServlet