Java Cryptography

SeederDialog

Wouldn’t it be nice if there were a modal dialog that used a Seeder to generate a seed value? And wouldn’t it be nice if the dialog had a progress bar that showed how far along the generation was? I’ll develop this nice dialog now.

SeederDialog is designed to make it easy to integrate Seeder into your application. Create one, show it, and retrieve the seed value as follows:

SeederDialog sd = new SeederDialog(this, 20);
sd.show();
byte[] seed = sd.getSeed();

The dialog itself is shown in Figure 4.1. As the user types characters, the progress bar fills up. When the seed is fully generated, the dialog goes away.

Figure 4-1. SeederDialog in action

SeederDialog is both an ActionListener and a KeyListener. It receives an ActionEvent from its Seeder when the seed is fully generated. It receives the same KeyEvents as the Seeder, which allows it to update the progress bar.

package oreilly.jonathan.awt;

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

import oreilly.jonathan.util.*;

public class SeederDialog
    extends Dialog
    implements ActionListener, KeyListener {

Internally, the dialog contains a Seeder object and a progress bar. (The progress bar is type oreilly.jonathan.awt.ProgressBar. I’ll present the code at the end of this section.)

  ProgressBar mProgressBar;
  Seeder mSeeder;

SeederDialog’s constructor accepts a parent Frame and a number of seed bytes. It creates itself as a modal dialog ...