MailClient.java

import java.io.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;

public class MailClient extends Frame {
  /* The stuff for the GUI. */
  private Button btSend = new Button("Send");
  private Button btClear = new Button("Clear");
  private Button btQuit = new Button("Quit");
  private Label serverLabel = new Label("Local mailserver:");
  private TextField serverField = new TextField("", 40);
  private Label fromLabel = new Label("From:");
  private TextField fromField = new TextField("", 40);
  private Label toLabel = new Label("To:");
  private TextField toField = new TextField("", 40);
  private Label subjectLabel = new Label("Subject:");
  private TextField subjectField = new TextField("", 40);
  private Label messageLabel = new Label("Message:");
  private TextArea messageText = new TextArea(10, 40);

  /**
   * Create a new MailClient window with fields for entering all
   * the relevant information (From, To, Subject, and message).
   */
  public MailClient() {
    super("Java Mailclient");

    /* Create panels for holding the fields. To make it look nice,
       create an extra panel for holding all the child panels. */
    Panel serverPanel = new Panel(new BorderLayout());
    Panel fromPanel = new Panel(new BorderLayout());
    Panel toPanel = new Panel(new BorderLayout());
    Panel subjectPanel = new Panel(new BorderLayout());
    Panel messagePanel = new Panel(new BorderLayout());
    serverPanel.add(serverLabel, BorderLayout.WEST);
    serverPanel.add(serverField, BorderLayout.CENTER);
    fromPanel.add(fromLabel, BorderLayout.WEST);
    fromPanel.add(fromField, BorderLayout.CENTER);
    toPanel.add(toLabel, BorderLayout.WEST);
    toPanel.add(toField, BorderLayout.CENTER);
    subjectPanel.add(subjectLabel, BorderLayout.WEST);
    subjectPanel.add(subjectField, BorderLayout.CENTER);
    messagePanel.add(messageLabel, BorderLayout.NORTH);
    messagePanel.add(messageText, BorderLayout.CENTER);
    Panel fieldPanel = new Panel(new GridLayout(0, 1));
    fieldPanel.add(serverPanel);
    fieldPanel.add(fromPanel);
    fieldPanel.add(toPanel);
    fieldPanel.add(subjectPanel);

    /* Create a panel for the buttons and add listeners to the
       buttons. */
    Panel buttonPanel = new Panel(new GridLayout(1, 0));
    btSend.addActionListener(new SendListener());
    btClear.addActionListener(new ClearListener());
    btQuit.addActionListener(new QuitListener());
    buttonPanel.add(btSend);
    buttonPanel.add(btClear);
    buttonPanel.add(btQuit);

    /* Add, pack, and show. */
    add(fieldPanel, BorderLayout.NORTH);
    add(messagePanel, BorderLayout.CENTER);
    add(buttonPanel, BorderLayout.SOUTH);
    pack();
    show();
  }

  static public void main(String argv[]) {
    new MailClient();
  }

  /* Handler for the Send-button. */
  class SendListener implements ActionListener {
    public void actionPerformed(ActionEvent event) {
      System.out.println("Sending mail");

      /* Check that we have the local mailserver */
      if ((serverField.getText()).equals("")) {
        System.out.println("Need name of local mailserver!");
        return;
      }

      /* Check that we have the sender and recipient. */
      if((fromField.getText()).equals("")) {
        System.out.println("Need sender!");
        return;
      }
      if((toField.getText()).equals("")) {
        System.out.println("Need recipient!");
        return;
      }

      /* Create the message */
      Message mailMessage = new Message(fromField.getText(),
          toField.getText(),
          subjectField.getText(),
          messageText.getText());

      /* Check that the message is valid, i.e., sender and
       *  recipient addresses look ok. */
      if(!mailMessage.isValid()) {
        return;
      }

      /* Create the envelope, open the connection and try to send
       *  the message. */
      Envelope envelope = null;
      try {
        envelope = new Envelope(mailMessage, serverField.getText());
      } catch (UnknownHostException e) {
        /* If there is an error, do not go further */
        return;
      }
      try {
        SMTPConnection connection = new SMTPConnection(envelope);
        connection.send(envelope);
        connection.close();
      } catch (IOException error) {
        System.out.println("Sending failed: " + error);
        return;
      }

      System.out.println("Mail sent succesfully!");
    }
  }

  /* Clear the fields on the GUI. */
  class ClearListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      System.out.println("Clearing fields");
      fromField.setText("");
      toField.setText("");
      subjectField.setText("");
      messageText.setText("");
    }
  }

  /* Quit. */
  class QuitListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      System.exit(0);
    }
  }
}