bookinformationscreen.java

java web services how to program

// Fig. 16.17: BookInformationScreen.java
// BookInformationScreen is a MIDlet screen that accesses and 
// displays the results of the BookDetails Web service.
package jws1casestudy.clients.j2me;

// import J2ME packages
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

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

class BookInformationScreen extends Form {

   // Form that selects a book on which to obtain information
   BookInformationScreen( final Display display )
   {
      super( "Select book to obtain info" );

      // ChoiceGroup that enables user to choose book
      final ChoiceGroup choices = 
         new ChoiceGroup( "", ChoiceGroup.EXCLUSIVE );
      choices.append( "0130895725", null );
      choices.append( "0130284181", null );
      choices.append( "0130341517", null );
      choices.append( "0130293636", null );
      choices.append( "0130895601", null );
      append( choices );

      // create soft button commands
      Command invokeCommand = 
         new Command( "Select", Command.OK, 0 );
      addCommand( invokeCommand );

      Command backCommand = 
         new Command( "Back", Command.BACK, 1 );
      addCommand( backCommand );

      // allow soft button access
      setCommandListener(
         new CommandListener() {

            // invoked when user presses soft button
            public void commandAction( 
               Command command, Displayable displayable )
            {
               // invoke service if user presses Select
               if ( command.getCommandType() == Command.OK ) {

                  // create object to invoke Web service
                  BookInformationService informationService = 
                     new BookInformationService();

                  // obtain isbn of book, based on user selection
                  int selection = choices.getSelectedIndex();
                  String isbn = choices.getString( selection );

                  // invoke Book Details Web service
                  BookDetails bookDetails = 
                     informationService.getBookDetails( isbn );

                  // display book details on success
                  if ( bookDetails != null )
                     display.setCurrent( new ResultScreen( 
                        bookDetails, display ) );

                  // display error page on failure
                  else
                  {
                     Alert errorPage = new Alert( "Error",
                        "Cannot invoke Web Service", null, 
                        AlertType.ERROR );
                     errorPage.setTimeout( 3000 );
                     display.setCurrent( errorPage );
                  }
               }

               // display MainScreen if user presses Back
               else if ( command.getCommandType() == 
                  Command.BACK )
                  display.setCurrent( new MainScreen( display ) );

            } // end method commandAction
         }
      );

   } // end BookInformationScreen constructor

   // Form to display book details after Web-service invocation
   private class ResultScreen extends Form {
      private BookDetails bookDetails;

      ResultScreen( BookDetails info, final Display display )
      {
         super( "Book Info" );
         bookDetails = info;

         // include book title on Form
         append( new StringItem( "", "Title: " + 
            bookDetails.getTitle() + '\n' ) );

         // include book ISBN on Form
         append( new StringItem( "", "ISBN: " + 
            bookDetails.getIsbn() + '\n'  ) );

         // include book authors on Form
         append( new StringItem( "", "Author: " + 
            bookDetails.getAuthors() + '\n'  ) );

         // include book description on Form
         append( new StringItem( "", "Description: " + 
            bookDetails.getDescription() + '\n'  ) );

         // create soft button command to view MainScreen
         Command okCommand = new Command( "OK", Command.OK, 0 );
         addCommand( okCommand );

         // allow soft button access
         setCommandListener(
            new CommandListener() {

               // view MainScreen when user presses OK
               public void commandAction( 
                  Command command, Displayable displayable )
               {
                  display.setCurrent( new MainScreen( display ) );
               }
            }
         );

      } // end ResultSet constructor

   } // end class ResultScreen

} // end class BookInformationScreen