emailclient.java

这是Java编程艺术一书附带的源代码

import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.util.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.swing.*;
import javax.swing.event.*;

// The E-mail Client.
public class EmailClient extends JFrame
{
  // Message table's data model.
  private MessagesTableModel tableModel;

  // Table listing messages.
  private JTable table;

  // This the text area for displaying messages.
  private JTextArea messageTextArea;

  /* This is the split panel that holds the messages
     table and the message view panel. */
  private JSplitPane splitPane;

  // These are the buttons for managing the selected message.
  private JButton replyButton, forwardButton, deleteButton;

  // Currently selected message in table.
  private Message selectedMessage;

  // Flag for whether or not a message is being deleted.
  private boolean deleting;

  // This is the JavaMail session.
  private Session session;

  // Constructor for E-mail Client.
  public EmailClient()
  {
    // Set application title.
    setTitle("E-mail Client");

    // Set window size.
    setSize(640, 480);

    // Handle window closing events.
    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        actionExit();
      }
    });

    // Setup file menu.
    JMenuBar menuBar = new JMenuBar();
    JMenu fileMenu = new JMenu("File");
    fileMenu.setMnemonic(KeyEvent.VK_F);
    JMenuItem fileExitMenuItem = new JMenuItem("Exit",
      KeyEvent.VK_X);
    fileExitMenuItem.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        actionExit();
      }
    });
    fileMenu.add(fileExitMenuItem);
    menuBar.add(fileMenu);
    setJMenuBar(menuBar);

    // Setup buttons panel.
    JPanel buttonPanel = new JPanel();
    JButton newButton = new JButton("New Message");
    newButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        actionNew ();
      }
    });
    buttonPanel.add(newButton);

    // Setup messages table.
    tableModel = new MessagesTableModel();
    table = new JTable(tableModel);
    table.getSelectionModel().addListSelectionListener(new
      ListSelectionListener() {
      public void valueChanged(ListSelectionEvent e) {
        tableSelectionChanged();
      }
    });
    // Allow only one row at a time to be selected.
    table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);

    // Setup E-mails panel.
    JPanel emailsPanel = new JPanel();
    emailsPanel.setBorder(
      BorderFactory.createTitledBorder("E-mails"));
    messageTextArea = new JTextArea();
    messageTextArea.setEditable(false);
    splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
      new JScrollPane(table), new JScrollPane(messageTextArea));
    emailsPanel.setLayout(new BorderLayout());
    emailsPanel.add(splitPane, BorderLayout.CENTER);

    // Setup buttons panel 2.
    JPanel buttonPanel2 = new JPanel();
    replyButton = new JButton("Reply");
    replyButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        actionReply();
      }
    });
    replyButton.setEnabled(false);
    buttonPanel2.add(replyButton);
    forwardButton = new JButton("Forward");
    forwardButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        actionForward();
      }
    });
    forwardButton.setEnabled(false);
    buttonPanel2.add(forwardButton);
    deleteButton = new JButton("Delete");
    deleteButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        actionDelete();
      }
    });
    deleteButton.setEnabled(false);
    buttonPanel2.add(deleteButton);

    // Add panels to display.
    getContentPane().setLayout(new BorderLayout());
    getContentPane().add(buttonPanel, BorderLayout.NORTH);
    getContentPane().add(emailsPanel, BorderLayout.CENTER);
    getContentPane().add(buttonPanel2, BorderLayout.SOUTH);
  }

  // Exit this program.
  private void actionExit() {
    System.exit(0);
  }

  // Create a new message.
  private void actionNew () {
    sendMessage(MessageDialog.NEW, null);
  }

  // Called when table row selection changes.
  private void tableSelectionChanged() {
    /* If not in the middle of deleting a message, set
       the selected message and display it. */
    if (!deleting) {
      selectedMessage =
        tableModel.getMessage(table.getSelectedRow());
      showSelectedMessage();
      updateButtons();
    }
  }

  // Reply to a message.
  private void actionReply() {
    sendMessage(MessageDialog.REPLY, selectedMessage);
  }

  // Forward a message.
  private void actionForward() {
    sendMessage(MessageDialog.FORWARD, selectedMessage);
  }

  // Delete the selected message.
  private void actionDelete() {
    deleting = true;

    try {
      // Delete message from server.
      selectedMessage.setFlag(Flags.Flag.DELETED, true);
      Folder folder = selectedMessage.getFolder();
      folder.close(true);
      folder.open(Folder.READ_WRITE);
    } catch (Exception e) {
      showError("Unable to delete message.", false);
    }

    // Delete message from table.
    tableModel.deleteMessage(table.getSelectedRow());

    // Update GUI.
    messageTextArea.setText("");
    deleting = false;
    selectedMessage = null;
    updateButtons();
  }

  // Send the specified message.
  private void sendMessage(int type, Message message) {
    // Display message dialog to get message values.
    MessageDialog dialog;
    try {
      dialog = new MessageDialog(this, type, message);
      if (!dialog.display()) {
        // Return if dialog was cancelled.
        return;
      }
    } catch (Exception e) {
      showError("Unable to send message.", false);
      return;
    }

    try {
      // Create a new message with values from dialog.
      Message newMessage = new MimeMessage(session);
      newMessage.setFrom(new InternetAddress(dialog.getFrom()));
      newMessage.setRecipient(Message.RecipientType.TO,
        new InternetAddress(dialog.getTo()));
      newMessage.setSubject(dialog.getSubject());
      newMessage.setSentDate(new Date());
      newMessage.setText(dialog.getContent());

      // Send new message.
      Transport.send(newMessage);
    } catch (Exception e) {
      showError("Unable to send message.", false);
    }
  }

  // Show the selected message in the content panel.
  private void showSelectedMessage() {
    // Show hour glass cursor while message is loaded.
    setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
    try {
      messageTextArea.setText(
        getMessageContent(selectedMessage));
      messageTextArea.setCaretPosition(0);
    } catch (Exception e) {
      showError("Unabled to load message.", false);
    } finally {
      // Return to default cursor.
      setCursor(Cursor.getDefaultCursor());
    }
  }

  /* Update each button's state based off of whether or not
     there is a message currently selected in the table. */
  private void updateButtons() {
    if (selectedMessage != null) {
      replyButton.setEnabled(true);
      forwardButton.setEnabled(true);
      deleteButton.setEnabled(true);
    } else {
      replyButton.setEnabled(false);
      forwardButton.setEnabled(false);
      deleteButton.setEnabled(false);
    }
  }

  // Show the application window on the screen.
  public void show() {
    super.show();

    // Update the split panel to be divided 50/50.
    splitPane.setDividerLocation(.5);
  }

  // Connect to e-mail server.
  public void connect() {
    // Display connect dialog.
    ConnectDialog dialog = new ConnectDialog(this);
    dialog.show();

    // Build connection URL from connect dialog settings.
    StringBuffer connectionUrl = new StringBuffer();
    connectionUrl.append(dialog.getType() + "://");
    connectionUrl.append(dialog.getUsername() + ":");
    connectionUrl.append(dialog.getPassword() + "@");
    connectionUrl.append(dialog.getServer() + "/");

    /* Display dialog stating that messages are
       currently being downloaded from server. */
    final DownloadingDialog downloadingDialog =
      new DownloadingDialog(this);
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        downloadingDialog.show();
      }
    });

    // Establish JavaMail session and connect to server.
    Store store = null;
    try {
      // Initialize JavaMail session with SMTP server.
      Properties props = new Properties();
      props.put("mail.smtp.host", dialog.getSmtpServer());
      session = Session.getDefaultInstance(props, null);

      // Connect to e-mail server.
      URLName urln = new URLName(connectionUrl.toString());
      store = session.getStore(urln);
      store.connect();
    } catch (Exception e) {
      // Close the downloading dialog.
      downloadingDialog.dispose();

      // Show error dialog.
      showError("Unable to connect.", true);
    }

    // Download message headers from server.
    try {
      // Open main "INBOX" folder.
      Folder folder = store.getFolder("INBOX");
      folder.open(Folder.READ_WRITE);

      // Get folder's list of messages.
      Message[] messages = folder.getMessages();

      // Retrieve message headers for each message in folder.
      FetchProfile profile = new FetchProfile();
      profile.add(FetchProfile.Item.ENVELOPE);
      folder.fetch(messages, profile);

      // Put messages in table.
      tableModel.setMessages(messages);
    } catch (Exception e) {
      // Close the downloading dialog.
      downloadingDialog.dispose();

      // Show error dialog.
      showError("Unable to download messages.", true);
    }

    // Close the downloading dialog.
    downloadingDialog.dispose();
  }

  // Show error dialog and exit afterwards if necessary.
  private void showError(String message, boolean exit) {
    JOptionPane.showMessageDialog(this, message, "Error",
      JOptionPane.ERROR_MESSAGE);
    if (exit)
      System.exit(0);
  }

  // Get a message's content.
  public static String getMessageContent(Message message)
    throws Exception {
    Object content = message.getContent();
    if (content instanceof Multipart) {
      StringBuffer messageContent = new StringBuffer();
      Multipart multipart = (Multipart) content;
      for (int i = 0; i < multipart.getCount(); i++) {
        Part part = (Part) multipart.getBodyPart(i);
          if (part.isMimeType("text/plain")) {
            messageContent.append(part.getContent().toString());
          }
        }
      return messageContent.toString();
    } else {
      return content.toString();
    }
  }

  // Run the E-mail Client.
  public static void main(String[] args) {
    EmailClient client = new EmailClient();
    client.show();

    // Display connect dialog.
    client.connect();
  }
}