www.pudn.com > SRS.rar > PasswordPopup.java

// PasswordPopup.java - Chapter 16 version. 
 
// Copyright 2000 by Jacquie Barker - all rights reserved. 
 
// A GUI class. 
 
import java.awt.*; 
import java.awt.event.*; 
import java.util.*; 
import javax.swing.*; 
 
public class PasswordPopup extends JDialog { 
	private String password; 
 
	// Attributes representing the GUI components. 
 
	private Container contentPane; 
	private JLabel passwordLabel; 
	private JPasswordField passwordField; 
 
	// Constructor. 
	public PasswordPopup(Frame parent) { 
		// Invoke the generic JDialog constructor first. 
 
		super(parent, "Enter Password", true); 
 
		contentPane = this.getContentPane(); 
		contentPane.setLayout(new GridLayout(1, 2)); 
 
		passwordLabel = new JLabel("Password:  ", JLabel.RIGHT); 
		passwordLabel.setForeground(Color.black); 
 
		passwordField = new JPasswordField(); 
		ActionListener aListener = new ActionListener() { 
			public void actionPerformed(ActionEvent e) { 
				// Retrieve the password. 
				char[] pw = passwordField.getPassword(); 
				password = new String(pw).trim(); 
 
				// Hide, but don't dispose of, this window ... 
				// we need to give the client code a chance to 
				// retrieve the user's typed response via 
				// the getPassword() method first. 
				PasswordPopup.this.setVisible(false); 
			} 
		}; 
		passwordField.addActionListener(aListener); 
 
		contentPane.add(passwordLabel); 
		contentPane.add(passwordField); 
 
		this.setSize(200, 60); 
 
		// Center it on the screen. 
		Dimension screenSize = Toolkit.getDefaultToolkit(). 
					    getScreenSize(); 
		Dimension popupSize = this.getSize(); 
	        int width = popupSize.width; 
		int height = popupSize.height; 
	    	this.setLocation((screenSize.width - width)/2,  
		                 (screenSize.height - height)/2); 
 
		this.setVisible(true); 
	} 
 
	public String getPassword() { 
		return password; 
	} 
 
	// Test scaffold. 
	public static void main(String[] args) { 
		PasswordPopup pp = new PasswordPopup(new JFrame()); 
		System.out.println("Password typed:  " + pp.getPassword()); 
		pp.dispose(); 
		System.exit(0); 
	} 
}