Trail: Security Features in Java SE
Lesson: Implementing Your Own Permission

ExampleGame

Below is the source code for ExampleGame. For simplicity, ExampleGame does not actually contain code to play a game. It simply retrieves or updates a user's high score.

To see what the user's current high score value is, you could run:

java ExampleGame get

To set a new high score value for the user, you could run:

java ExampleGame set score

To retrieve the user's current high score, ExampleGame simply instantiates a HighScore object and makes a call to its getHighScore method. To set a new high score for the user, ExampleGame instantiates a HighScore object and calls setHighScore, passing it the user's new high score.

Here is the source code for ExampleGame, ExampleGame.java:


package com.gamedev.games;

import java.io.*;
import java.security.*;
import java.util.Hashtable;
import com.scoredev.scores.*;

public class ExampleGame
{
    public static void main(String args[])
	throws Exception 
    {
	HighScore hs = new HighScore("ExampleGame");

	if (args.length == 0)
	    usage();

	if (args[0].equals("set")) {
	    hs.setHighScore(Integer.parseInt(args[1]));
	} else if (args[0].equals("get")) {
	    System.out.println("score = "+ hs.getHighScore());
	} else {
	    usage();
	}
    }

    public static void usage()
    {
	System.out.println("ExampleGame get");
	System.out.println("ExampleGame set <score>");
	System.exit(1);
    }
}