booktitlesproxy.java

java web services how to program

// Fig. 11.8: BookTitlesProxy.java.
// Class BookTitlesProxy uses JAXM to invoke the Book Titles 
// Web service, which returns a list of available book titles.
package com.deitel.jws1.jaxm.client;

// Java core packages
import java.io.*;
import java.util.Iterator;
import java.util.Properties;

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

public class BookTitlesProxy {

   private SOAPConnectionFactory soapConnectionFactory;
   private URLEndpoint urlEndpoint;
   private MessageFactory messageFactory;

   // initialize BookTitlesProxy
   public BookTitlesProxy() throws java.io.IOException
   {
      // create factory objects
      try {

         // factory for establishing point-to-point connections
         soapConnectionFactory = 
            SOAPConnectionFactory.newInstance();

         // factory for building SOAP messages
         messageFactory = MessageFactory.newInstance();

         // obtain URL of properties file
         java.net.URL propertyURL = getClass().getResource( 
            "JAXMWebService.properties" );

         // load properties file
         Properties serviceProperties = new Properties();
         serviceProperties.load( new FileInputStream( 
            propertyURL.getPath() ) );

         // create endpoint using properties file
         String endpoint = serviceProperties.getProperty( 
            "bookTitlesServiceURL" );

         // define URL of Web-service provider
         urlEndpoint = new URLEndpoint( endpoint );
      }

      // handle exception in initializing factory objects
      catch ( SOAPException exception ) {
         throw new IOException( exception.getMessage() );
      }

   } // end constructor

   // use JAXM to invoke remote Web service
   public String[] getBookTitles()
   {
      // invoke Web service and convert result to String array
      try {
         SOAPMessage response = sendSoapRequest();

         // return SOAP response
         return handleSoapResponse( response );
      }

      // handle exception in sending or receiving SOAP message
      catch ( SOAPException exception ) {
         return null;
      }

   } // end method getBookTitles

   // invoke remote Web service by sending SOAP request
   private SOAPMessage sendSoapRequest() throws SOAPException
   {
      // use SOAPConnectionFactory to create SOAP connection
      SOAPConnection soapConnection = 
            soapConnectionFactory.createConnection();

      // use MessageFactory to create SOAP message
      SOAPMessage soapRequest = messageFactory.createMessage();

      // send SOAP message to Web-service provider
      SOAPMessage soapResponse = soapConnection.call( 
         soapRequest, urlEndpoint );

      soapConnection.close();

      return soapResponse; // return Web-service response

   } // end method sendSoapRequest

   // convert SOAP message returned by Web service to array of 
   // Strings, in which each String represents a book title
   private String[] handleSoapResponse( SOAPMessage soapResponse )
      throws SOAPException
   {
      // obtain references to response message elements
      SOAPPart responsePart = soapResponse.getSOAPPart();
      SOAPEnvelope responseEnvelope = responsePart.getEnvelope();
      SOAPBody responseBody = responseEnvelope.getBody();

      // obtain Iterator of all child elements of element Body
      Iterator responseBodyChildElements = 
         responseBody.getChildElements();

      // extract element titles from SOAP message element Body
      SOAPBodyElement titlesElement =
         ( SOAPBodyElement ) responseBodyChildElements.next();

      // extract number of book titles from element Titles
      int bookCount = Integer.parseInt( 
         titlesElement.getAttributeValue(
            responseEnvelope.createName( "bookCount" ) ) );

      // create array of Strings that represent book titles
      String bookTitles[] = new String[ bookCount ];

      // use Iterator to obtain child elements of element titles
      Iterator titleIterator = 
         titlesElement.getChildElements( 
            responseEnvelope.createName( "title" ));

      // store each book title in bookTitles String array
      int i = 0;
      while ( titleIterator.hasNext() ) {
         SOAPElement titleElement =
            ( SOAPElement ) titleIterator.next();
         bookTitles[ i++ ] = titleElement.getValue();
      }

      return bookTitles;

   } // end method handleSoapResponse

} // end class BookTitlesProxy