初期JAVA学习非常有用的资料。帮助深入了解API。特别是Applet。

				/* 				 * 1.1 version.				 */								import java.applet.*;				import java.awt.*;				import java.awt.event.*;				import java.util.Enumeration;								public class Sender extends Applet 				                    implements ActionListener {				    private String myName;				    private TextField nameField;				    private TextArea status;				    private String newline;								    public void init() {				        GridBagLayout gridBag = new GridBagLayout();				        GridBagConstraints c = new GridBagConstraints();								        setLayout(gridBag);								        Label receiverLabel = new Label("Receiver name:", 				                                        Label.RIGHT);				        gridBag.setConstraints(receiverLabel, c);				        add(receiverLabel);								        nameField = new TextField(getParameter("RECEIVERNAME"),				                                               10);				        c.fill = GridBagConstraints.HORIZONTAL;				        gridBag.setConstraints(nameField, c);				        add(nameField);				        nameField.addActionListener(this);								        Button button = new Button("Send message");				        c.gridwidth = GridBagConstraints.REMAINDER; //end row				        c.anchor = GridBagConstraints.WEST; //stick to the 				                                            //text field				        c.fill = GridBagConstraints.NONE; //keep the button 				                                          //small				        gridBag.setConstraints(button, c);				        add(button);				        button.addActionListener(this);								        status = new TextArea(5, 60);				        status.setEditable(false);				        c.anchor = GridBagConstraints.CENTER; //reset to the default				        c.fill = GridBagConstraints.BOTH; //make this big				        c.weightx = 1.0;				        c.weighty = 1.0;				        gridBag.setConstraints(status, c);				        add(status);								        myName = getParameter("NAME");				        Label senderLabel = new Label("(My name is " + myName + ".)",				                                      Label.CENTER);				        c.weightx = 0.0;				        c.weighty = 0.0;				        gridBag.setConstraints(senderLabel, c);				        add(senderLabel);									newline = System.getProperty("line.separator");				    }								    public void actionPerformed(ActionEvent event) {				        Applet receiver = null;				        String receiverName = nameField.getText(); //Get name to 				                                                   //search for.				        receiver = getAppletContext().getApplet(receiverName);				        if (receiver != null) {				            //Use the instanceof operator to make sure the applet				            //we found is a Receiver object.				            if (!(receiver instanceof Receiver)) {				                status.append("Found applet named "				                              + receiverName + ", "				                              + "but it's not a Receiver object."							      + newline);				            } else {				                status.append("Found applet named "				                              + receiverName + newline				                              + "  Sending message to it."							      + newline);				                //Cast the receiver to be a Receiver object				                //(instead of just an Applet object) so that the				                //compiler will let us call a Receiver method.				                ((Receiver)receiver).processRequestFrom(myName);				            }				        } else {				            status.append("Couldn't find any applet named "				                          + receiverName + "." + newline);				        }				    }								    public Insets getInsets() {				        return new Insets(3,3,3,3);				    }								    public void paint(Graphics g) {				        g.drawRect(0, 0, 				                   getSize().width - 1, getSize().height - 1);				    }								    public String getAppletInfo() {				        return "Sender by Kathy Walrath";				    }				}