sender.java

几个简单的java学习代码

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

import javax.swing.*;

import java.util.Enumeration;

public class Sender extends JApplet
                    implements ActionListener {
    private String myName;
    private JTextField nameField;
    private JTextArea status;
    private String newline;

    public void init() {
        GridBagLayout gridBag = new GridBagLayout();
        GridBagConstraints c = new GridBagConstraints();

        JPanel panel = new JPanel();
         panel.setLayout(gridBag);

         panel.setBorder(BorderFactory.createCompoundBorder(
                          BorderFactory.createEmptyBorder(10,10,10,10),
                        BorderFactory.createLineBorder(Color.black )));


        JLabel receiverLabel = new JLabel("Receiver name:",
                                        JLabel.RIGHT);

        gridBag.setConstraints(receiverLabel, c);
        panel.add(receiverLabel);

        nameField = new JTextField(getParameter("receiverName"),30);

        c.fill = GridBagConstraints.HORIZONTAL ;
              c.gridwidth = GridBagConstraints.REMAINDER; //end row
        gridBag.setConstraints(nameField, c);
        panel.add(nameField);

        nameField.addActionListener(this);

        JButton button = new JButton("Send message");
        c.gridwidth = GridBagConstraints.REMAINDER; //end row
      c.anchor = GridBagConstraints.CENTER ; //stick to the
                                            //text field
        c.fill = GridBagConstraints.NONE; //keep the button
                                          //small
        gridBag.setConstraints(button, c);
        panel.add(button);
        button.addActionListener(this);

        status = new JTextArea(5, 60);
        status.setEditable(false);
        JScrollPane scrollPane = new JScrollPane(status);
        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(scrollPane, c);
        panel.add(scrollPane);

        myName = getParameter("NAME");
        JLabel senderLabel = new JLabel("(My name is " + myName + ".)",
                                      JLabel.CENTER);
        c.weightx = 0.0;
        c.weighty = 0.0;
        gridBag.setConstraints(senderLabel, c);
        panel.add(senderLabel);

	newline = System.getProperty("line.separator");
        this.setContentPane(panel);

    }

    public void actionPerformed(ActionEvent event) {
        Applet receiver = null;
        String receiverName = nameField.getText(); //Get name to
                                                   //search for.
        receiver = getAppletContext().getApplet(receiverName);
        if (receiver != null) {

            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 String getAppletInfo() {
        return "Sender by Kathy Walrath";
    }
}