SendMailApp.java

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import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.text.SimpleDateFormat;
import java.util.Calendar;

import javax.mail.MessagingException;
import javax.swing.GroupLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.WindowConstants;
import javax.swing.plaf.metal.MetalBorders;

/**
 *  Simple SMTP send mail application that demonstrates usage of the MailTransport class.
 *  It also offers presentation context for instances of MailTransport. 
 *  
 *  @author Mikica B Kocic
 */
public class SendMailApp extends JFrame 
    implements ActionListener, MailTransport.Context
{
    /**
     *  Implements java.io.Serializable interface
     */
    private static final long serialVersionUID = 6679954030573701419L;

    /**
     *  Common application title prefix.
     */
    private final static String appTitle = "IP1-6.1: SMTP Send Mail";
    
    /**
     *  GUI components
     */
    private JButton     buttonEnqueue;
    private JButton     buttonSend;
    
    private JLabel      labelServer;
    private JTextField  fieldServer;
    private JLabel      labelFrom;
    private JTextField  fieldFrom;
    private JLabel      labelTo;
    private JTextField  fieldTo;
    private JLabel      labelSubject;
    private JTextField  fieldSubject;
    private JScrollPane messageScrollPane;
    private JTextArea   messageContents;
    
    private JTabbedPane tabbedPane;
    
    private JScrollPane logPane;
    private JTextArea   logArea;
    
    /**
     *  Instance of the current mail transport channel.
     */
    private MailTransport mailTransport = null;

    /**
     *  Creates an instance of the send mail application GUI.
     */
    public SendMailApp ()
    {
        super( appTitle + ", idle" );
            
        setDefaultCloseOperation( WindowConstants.EXIT_ON_CLOSE );
        
        /////////////////////////////////////////////////////// GUI COMPONENTS ///////////
        
        addWindowListener( new java.awt.event.WindowAdapter () {
            public void windowClosing( java.awt.event.WindowEvent evt ) {
                formWindowClosing( evt );
            }
        });

        Font btnFont  = new Font( Font.SANS_SERIF, Font.BOLD,  12 );
        Font textFont = new Font( Font.SANS_SERIF, Font.PLAIN, 15 );
        Font logFont  = new Font( Font.MONOSPACED, Font.PLAIN, 14 );
        
        buttonEnqueue    = new JButton ();
        buttonSend       = new JButton ();
        labelServer      = new JLabel ();
        fieldServer       = new JTextField ();
        labelFrom        = new JLabel ();
        fieldFrom         = new JTextField ();
        labelTo          = new JLabel ();
        fieldTo           = new JTextField ();
        labelSubject     = new JLabel ();
        fieldSubject      = new JTextField ();

        labelServer.setText( "STMP Server:" );
        labelFrom.setText( "From:" );
        labelTo.setText( "To:" );
        labelSubject.setText( "Subject:" );
        
        fieldServer.setColumns( 40 );
        fieldFrom.setColumns( 40 );
        fieldTo.setColumns( 40 );
        fieldSubject.setColumns( 40 );

        buttonEnqueue.setFont( btnFont );
        buttonSend.setFont( btnFont );
        labelServer.setFont( textFont );
        labelFrom.setFont( textFont );
        labelTo.setFont( textFont );
        labelSubject.setFont( textFont );
        fieldServer.setFont( textFont );
        fieldFrom.setFont( textFont );
        fieldTo.setFont( textFont );
        fieldSubject.setFont( textFont );

        messageContents = new JTextArea ();
        messageContents.setLineWrap( true );
        messageContents.setWrapStyleWord( true );
        messageContents.setEditable( true );
        messageContents.setFont( textFont );

        messageScrollPane = new JScrollPane ();
        messageScrollPane.setViewportView( messageContents );
        
        logArea = new JTextArea ();
        logArea.setLineWrap( true );
        logArea.setWrapStyleWord( true );
        logArea.setEditable( false );
        logArea.setFont( logFont );
        logArea.setBackground( new Color( 255, 255, 240 ) );
        logArea.setForeground( Color.BLACK );
        logArea.setWrapStyleWord( true );
        
        logPane = new JScrollPane ();
        logPane.setViewportView( logArea );

        buttonEnqueue.setText( "Enqueue Message" );
        buttonEnqueue.addActionListener( this );

        buttonSend.setText( "Send Immediatelly" );
        buttonSend.addActionListener( this );

        /////////////////////////////////////////////////////// COMPONENTS LAYOUT ////////

        JPanel sendMailPane = new JPanel (); 
        sendMailPane.setBorder( new MetalBorders.Flush3DBorder() );
        
        GroupLayout layout = new GroupLayout( sendMailPane );
        sendMailPane.setLayout( layout );
        layout.setAutoCreateContainerGaps( true );
        layout.setAutoCreateGaps( true );
        
        layout.setHorizontalGroup
        (
            layout
            .createParallelGroup( GroupLayout.Alignment.LEADING )
            .addGroup
            (
                layout
                .createSequentialGroup ()
                .addGroup
                (
                    layout
                    .createParallelGroup( GroupLayout.Alignment.TRAILING )
                    .addComponent( messageScrollPane )
                    .addGroup
                    (
                        GroupLayout.Alignment.LEADING, 
                        layout
                        .createSequentialGroup ()
                        .addContainerGap( 10, 10 )
                        .addGroup
                        (
                            layout
                            .createParallelGroup( GroupLayout.Alignment.LEADING )
                            .addComponent( labelServer )
                            .addComponent( labelFrom )
                            .addComponent( labelTo )
                            .addComponent( labelSubject )
                        )
                        .addGroup
                        (
                            layout
                            .createParallelGroup( GroupLayout.Alignment.LEADING, false )
                            .addComponent( fieldServer )
                            .addComponent( fieldFrom )
                            .addComponent( fieldTo )
                            .addComponent( fieldSubject )
                        )
                    )
                    .addGroup
                    (
                        GroupLayout.Alignment.LEADING,
                        layout
                        .createSequentialGroup ()
                        .addContainerGap( 10, 10 )
                        .addGroup
                        (
                            layout
                            .createParallelGroup( GroupLayout.Alignment.LEADING, false )
                            .addComponent( buttonEnqueue )
                        )
                        .addGroup
                        (
                            layout
                            .createParallelGroup( GroupLayout.Alignment.LEADING, false )
                            .addComponent( buttonSend )
                        )
                    )
                )
            )
        );
        
        layout.setVerticalGroup
        (
            layout
            .createParallelGroup( GroupLayout.Alignment.LEADING )
            .addGroup
            (
                layout
                .createSequentialGroup ()
                .addGroup
                (
                    layout
                    .createParallelGroup( GroupLayout.Alignment.BASELINE )
                    .addComponent( labelServer )
                    .addComponent( fieldServer )
                )
                .addGroup
                (
                    layout
                    .createParallelGroup( GroupLayout.Alignment.BASELINE )
                    .addComponent( labelFrom )
                    .addComponent( fieldFrom )
                )
                .addGroup
                (
                    layout
                    .createParallelGroup( GroupLayout.Alignment.BASELINE )
                    .addComponent( labelTo )
                    .addComponent( fieldTo )
                )
                .addGroup
                (
                    layout.createParallelGroup( GroupLayout.Alignment.BASELINE )
                    .addComponent( labelSubject )
                    .addComponent( fieldSubject )
                )
                .addGroup
                (
                    layout.createParallelGroup( GroupLayout.Alignment.BASELINE )
                    .addComponent( buttonEnqueue )
                    .addComponent( buttonSend )
                )
                .addComponent( messageScrollPane )
            )
        );

        pack ();

        /////////////////////////////////////////////////////// TABBED PANES /////////////
        
        tabbedPane = new JTabbedPane ();
        getContentPane().add( tabbedPane );
        tabbedPane.addTab( "Compose Message", sendMailPane );
        tabbedPane.addTab( "MTA: Idle", logPane );

        /////////////////////////////////////////////////////// WINDOW PLACEMENT /////////
        
        /* Adjust window dimensions not to exceed screen dimensions ...
         */
        Dimension win = new Dimension( 695, 590 );
        Dimension scsz = Toolkit.getDefaultToolkit().getScreenSize();
        win.width  = Math.min( win.width, scsz.width );
        win.height = Math.min( win.height, scsz.height - 40 );
        setMinimumSize( win );
        setSize( win );
        
        /* ... then center window on the screen.
         */
        setLocation( ( scsz.width - win.width )/2, ( scsz.height - 40 - win.height )/2 );
        
        /* Ready for user to type in...
         */
        fieldServer.requestFocus ();
    }

    /**
     *  Enqueues message and optionally flushes the queue. It creates new instance of the
     *  mail transport channel (if there is no any and also keeps GUI elements 
     *  synchronized with the current state of the mail transport instance.  
     */
    private void enqueueMessage( boolean sendImmediately )
    {
        try 
        {
            /* Create new instance of mail transport (if there is no any) and lock the 
             * server input field so the user cannot change server name 
             * until the queue is flushed (because all subsequent messages
             * will be enqueued in the queue of the currently created MailTransport
             * instance). 
             */
            synchronized( this ) 
            {
                if ( mailTransport == null ) {
                    mailTransport = new MailTransport( this, fieldServer.getText(), 25 );
                    fieldServer.setEnabled( false );
                }
            }

            /* Now, create and put the message into sending queue of the mail transport...
             */
            String   from       = fieldFrom.getText().trim(); 
            String[] recipients = fieldTo.getText().trim().split(",");
            String   subject    = fieldSubject.getText().trim();
            String   contents   = messageContents.getText().trim();
           
            /* Enqueue message only if there is recipient specified
             */
            if ( recipients.length > 0 && ! recipients[0].isEmpty () )
            {
                mailTransport.enqueueMessage( from, recipients, subject, contents );

                int msgCount = mailTransport.getQueueSize ();
                assert msgCount > 0 
                    : "Ouch!. We have enqueued message, but the queue is still empty?";
                if ( msgCount == 1 ) {
                    setTitle( appTitle + ", 1 message waiting to be sent..." );
                } else {
                    setTitle( appTitle + ", " + msgCount 
                            + " messages waiting to be sent..." );
                }
                
                /* Keep "From:" field and clear other variable fields
                 */
                fieldTo.setText( "" );
                fieldSubject.setText( "" );
                messageContents.setText( "" );
            }
            
            /* If user wants to flush the queue, then start the worker thread
             * and indicate that we have no more messages to send, then release
             * mailTransport agent.
             */
            if ( sendImmediately && mailTransport.getQueueSize () > 0 )
            {
                println( "------------------------------------------------------------" );

                tabbedPane.setForegroundAt( 1, Color.BLUE );
                tabbedPane.setTitleAt( 1, "MTA: Sending..." );
                tabbedPane.setSelectedIndex( 1 );
                setTitle( appTitle + ", Sending messages..." );
                
                mailTransport.noMoreMessages ();
                mailTransport.startSending ();
                
                /* Release mailTransport agent and unlock the server field
                 */
                mailTransport = null;
                fieldServer.setEnabled( true );
            }
            else if ( mailTransport.getQueueSize () == 0 )
            {
                tabbedPane.setForegroundAt( 1, Color.BLACK );
                tabbedPane.setTitleAt( 1, "MTA: Idle" );
                setTitle( appTitle + ", idle" );
                
                /* Release mailTransport agent and unlock the server field
                 */
                mailTransport = null;
                fieldServer.setEnabled( true );
            }
            else
            {
                tabbedPane.setForegroundAt( 1, Color.BLACK );
                tabbedPane.setTitleAt( 1, "MTA: Idle" );
            }
        }
        catch( MessagingException e )
        {
            JOptionPane.showMessageDialog( this, 
                    "Failed to put e-mail message into the queue\n" + e.toString (), 
                    "Error while enqueing the message...", JOptionPane.ERROR_MESSAGE );
        }
    }
    
    /**
     *  Clears the log
     */
    public void clearLog ()
    {
        synchronized( logArea )
        {
            logArea.setText( "" );
            logArea.setRows( 0 );
            logArea.setCaretPosition( logArea.getText().length () );
        }
    }

    /**
     *  Gets current time stamp
     *  
     *  @return time in ISO format 
     */
    private static String now ()
    {
        Calendar cal = Calendar.getInstance ();
        SimpleDateFormat sdf = new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss" );
        return sdf.format( cal.getTime() );
    }

    /**
     *  Logs message terminated with new line
     *  
     *  @param str    message that will be logged
     */
    @Override
    public void println( String str )
    {
        synchronized( logArea )
        {
            logArea.append( now () + "  " + str + "\n" );
            logArea.setRows( logArea.getRows () + 1 );
            logArea.setCaretPosition( logArea.getText().length () );
        }
    }
    
    /**
     *  On send completed call-back
     *  
     *  @param errorMessage    contains an error message if not null, otherwise success
     */
    public void onSendCompleted( String errorMessage )
    {
        synchronized ( this )
        {
            int msgCount = mailTransport == null ? 0 : mailTransport.getQueueSize ();
            if ( msgCount == 0 ) {
                setTitle( appTitle + ", idle" );
            } else if ( msgCount == 1 ) {
                setTitle( appTitle + ", 1 message waiting to be sent..." );
            } else {
                setTitle( appTitle + ", " + msgCount 
                        + " messages waiting to be sent..." );
            }
        }

        if ( errorMessage != null ) {
            // tabbedPane.setSelectedIndex( 1 );
            tabbedPane.setForegroundAt( 1, Color.RED );
            tabbedPane.setTitleAt( 1, "MTA: Error!" );

            /* Commented because we don't want to disturb user...
             * 
            JOptionPane.showMessageDialog( this, 
                    "Failed to send e-mail messages from queue!\n"
                    + "Please, check the log for more details...\n"
                    + errorMessage,
                    "Error while flushing the queue...", 
                    JOptionPane.ERROR_MESSAGE );
            */
        } else {
            tabbedPane.setForegroundAt( 1, new Color( 0, 128, 0 ) ); // dark green
            tabbedPane.setTitleAt( 1, "MTA: OK" );
        }
    }
    
    /**
     *  Closes application gracefully
     * 
     *  @param evt
     */
    private void formWindowClosing( WindowEvent evt )
    {
        /* Signal to mail transport's worker thread to flush the queue before exit
         */
        synchronized( this ) 
        {
            if ( mailTransport != null ) {
                mailTransport.noMoreMessages ();
                mailTransport = null;
            }
        }

        System.exit( 0 );
    }

    /**
     *  Handles events from 'enqueue' and 'send immediately' buttons.
     */
    public void actionPerformed( ActionEvent evt )
    {
        boolean sendImmediately = ( evt.getSource () == buttonSend );
        
        enqueueMessage( sendImmediately );
    }

    /**
     *  Main entry point. Creates instance of <code>SendMailApp</code> application.
     *  
     *  @param args the command line arguments
     */
    public static void main( String args[] ) 
    {
        java.awt.EventQueue.invokeLater( 
                new Runnable() {
                    public void run() {
                        new SendMailApp ().setVisible( true );
                    }
                }
            );
    }
}

/*! 
 *  \mainpage Simple SMTP Client
 *
 *  \section s_intro Introduction
 *  
 *  The package implements solution to \ref p_task as a part of 
 *  the <a href="http://dsv.su.se/utbildning/distans/ip1" target="_blank"><b>SU/IP1 
 *  course</b></a>.
 *  
 *  \image html sendMailApp.png
 *  
 *  \section s_desc Description
 *
 *  The application is the simple SMTP client GUI that demonstrates usage of the 
 *  MailTransport class built on the top of 
 *  <a href="http://www.oracle.com/technetwork/java/index-jsp-139225.html" target="_blank">
 *  <b>Javamail</b></a> extension to JDK.
 *  
 *  The user has possibility to either compose one by one textual message and 
 *  send them immediately or compose several textual messages in a raw and 
 *  send them together.
 *  
 *  After the first message is put into outgoing queue, application does not allow user
 *  to change selected server (until the queue is released with <i>Send Immediatelly</i>
 *  button).
 *   
 *  \subsection s_mta The Mail Transport Client
 *
 *  The MailTransport class encapsulates mail transport agent with FIFO queue and 
 *  non-blocking send capabilities. Instances of this class may be used in two different
 *  scenarios.
 *  (Note the position of MailTransport.startSending() method and the usage of 
 *  MailTransport.noMoreMessages() bellow.)
 *  
 *  <hr><div style='color:darkred;font-weight:bold'>
 *  Scenario 1: Sends one or more messages at once.</div>
 *  
 *  Usage:
 *        - create instance using constructor MailTransport.MailTransport() 
 *          (with SMTP server as parameter)
 *        - call MailTransport.enqueueMessage()
 *        - call MailTransport.enqueueMessage()
 *        - ...
 *        - call MailTransport.noMoreMessages() to terminate worker thread
 *        - call MailTransport.startSending()
 *        
 *  <hr><div style='color:darkred;font-weight:bold'>
 *  Scenario 2. Works in background as relay client to SMTP server.</div>
 *
 *  Usage:
 *        - create instance using constructor MailTransport.MailTransport() 
 *          (with SMTP server as parameters)
 *        - call MailTransport.startSending()
 *        - call MailTransport.enqueueMessage()
 *        - call MailTransport.enqueueMessage()
 *        - ...
 *
 *  <hr>
 *  \section s_jar Executable
 *  
 *  The jar file of the package can be found 
 *  <a href="../sendMail.jar"><b>here</b></a>.
 *  
 *  The jar also includes repacked <code>mail.jar</code> retrieved from 
 *  <a href="http://www.oracle.com/technetwork/java/index-138643.html" target="_blank">
 *  JavaMail 1.4.3</a>.
 *  
 *  \section s_src Sources
 *  
 *  Source files:
 *   - \ref MailTransport.java
 *   - \ref SendMailApp.java
 */
/*! \page p_task IP1-6.1 Uppgift
 *  
 *  Gör ett fristående program med ett grafiskt användargränssnitt som med hjälp av 
 *  JDK-extensionen Javamail kan sända e-post. Användaren ska kunna skriva in följande:
 *  
 *   - Mail-server
 *   - Från
 *   - Till
 *   - Ämne
 *   - Meddelande 
 *
 */