impeerlistener.java

java2高级教程大学教程的配套光盘源码

// IMPeerListener.java
// IMPeerListener extends JFrame and provides GUI for 
// conversations with other peers 
package com.deitel.advjhtp1.jini.IM.client;

// Java core packages
import java.awt.*;
import java.awt.event.*;
import java.rmi.RemoteException;

// Java extension packages
import javax.swing.*;
import javax.swing.text.*;
import javax.swing.border.*;

// Deitel Packages
import com.deitel.advjhtp1.jini.IM.IMPeer;
import com.deitel.advjhtp1.jini.IM.Message;

public class IMPeerListener extends JFrame {

   // JTextAreas for displaying and inputting messages
   private JTextArea messageArea;
   private JTextArea inputArea;
   
   // Actions for sending messages, etc.
   private Action sendAction;
   
   // userName to add to outgoing messages
   private String userName = "";
   
   // IMPeer to send messages to peer
   private IMPeer remotePeer;
   
   // constructor   
   public IMPeerListener( String name )
   {
      super( "Conversation Window" );
      
      // set user name
      userName = name;
      
      // init sendAction
      sendAction = new SendAction();
      
      // create JTextArea for displaying messages
      messageArea = new JTextArea( 15, 15 );
      
      // disable editing and wrap words at end of line
      messageArea.setEditable( false );
      messageArea.setLineWrap( true );
      messageArea.setWrapStyleWord( true );
      
      JPanel panel = new JPanel();
      panel.setLayout( new BorderLayout( 5, 5 ) );
      panel.add( new JScrollPane( messageArea ), 
         BorderLayout.CENTER );
      
      // create JTextArea for entering new messages
      inputArea = new JTextArea( 4, 12 );   
      inputArea.setLineWrap( true );
      inputArea.setWrapStyleWord( true );
      
      // map Enter key in inputArea area to sendAction
      Keymap keyMap = inputArea.getKeymap();
      KeyStroke enterKey = KeyStroke.getKeyStroke(
         KeyEvent.VK_ENTER, 0 );
      keyMap.addActionForKeyStroke( enterKey, sendAction );
      
      // lay out inputArea and sendAction JButton in Box
      Box box = Box.createVerticalBox();
      box.add( new JScrollPane( inputArea ) );
      box.add( new JButton( sendAction ) );
      
      panel.add( box, BorderLayout.SOUTH );
      
      // lay out components
      Container container = getContentPane();
      container.add( panel, BorderLayout.CENTER );
                           
      setSize( 200, 400 );
      setVisible( true );
   }
   
   // Action for sending messages
   private class SendAction extends AbstractAction {
      
      // configure SendAction
      public SendAction()
      {
         putValue( Action.NAME, "Send" );
         putValue( Action.SHORT_DESCRIPTION, 
            "Send Message" );
         putValue( Action.LONG_DESCRIPTION, 
            "Send an Instant Message" );
      }
      
      // send message and clear inputArea
      public void actionPerformed( ActionEvent event )
      {
         // send message to server
         try {
            Message message = new Message( userName, 
               inputArea.getText() );
            
            // use RMI reference to send a Message
            remotePeer.sendMessage( message );
            
            // clear inputArea
            inputArea.setText( "" );
            displayMessage( message );
         }
         
         // catch error sending message
         catch( RemoteException remoteException ) {
            JOptionPane.showMessageDialog( null,
               "Unable to send message." );
            
            remoteException.printStackTrace();
         }      
      } // end method actionPerformed
   } // end sendAction inner class
       
   public void displayMessage( Message message )
   {
      // displayMessage uses SwingUntilities.invokeLater 
      // to ensure thread-safe access to messageArea
      SwingUtilities.invokeLater(
         new MessageDisplayer( 
            message.getSenderName(), message.getContent() ) );
   }
   
   // MessageDisplayer displays a new message by appending
   // the message to the messageArea JTextArea. This Runnable
   // object should be executed only on the event-dispatch
   // thread, as it modifies a live Swing component.
   private class MessageDisplayer implements Runnable {
 
      private String fromUser;
      private String messageBody;

      // MessageDisplayer constructor
      public MessageDisplayer( String from, String body )
      {
         fromUser = from;
         messageBody = body;
      }

      // display new message in messageArea
      public void run() 
      {
         // append new message
         messageArea.append( "\n" + fromUser + "> " + 
            messageBody );   

         // move caret to end of messageArea to ensure new 
         // message is visible on screen
         messageArea.setCaretPosition( 
            messageArea.getText().length() );                    
      }     

   }  // end MessageDisplayer inner class   
   
   // addPeer takes IMPeer as arg
   // associates IMPeer with sendAction to send messages
   public void addPeer( IMPeer peer ) throws RemoteException
   {
      remotePeer = peer;
      
      // change title of window to name of peer
      setTitle( remotePeer.getName() );
   }  
} 

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