Implementing Your Own Permission
\npackage com.gamedev.games;<\/p>\n
import java.io.*;
\nimport java.security.*;
\nimport java.util.Hashtable;
\nimport com.scoredev.scores.*;<\/p>\n
public class ExampleGame
\n{
\n public static void main(String args[])
\n\tthrows Exception
\n {
\n\tHighScore hs = new HighScore(“ExampleGame”);<\/p>\n
\tif (args.length == 0)
\n\t usage();<\/p>\n
\tif (args[0].equals(“set”)) {
\n\t hs.setHighScore(Integer.parseInt(args[1]));
\n\t} else if (args[0].equals(“get”)) {
\n\t System.out.println(“score = “+ hs.getHighScore());
\n\t} else {
\n\t usage();
\n\t}
\n }<\/p>\n
public static void usage()
\n {
\n\tSystem.out.println(“ExampleGame get”);
\n\tSystem.out.println(“ExampleGame set “);
\n\tSystem.exit(1);
\n }
\n}<\/p>\n
—<\/p>\n
\/*
\n * Copyright (c) 1995, 2008, Oracle and\/or its affiliates. All rights reserved.
\n *
\n * Redistribution and use in source and binary forms, with or without
\n * modification, are permitted provided that the following conditions
\n * are met:
\n *
\n * – Redistributions of source code must retain the above copyright
\n * notice, this list of conditions and the following disclaimer.
\n *
\n * – Redistributions in binary form must reproduce the above copyright
\n * notice, this list of conditions and the following disclaimer in the
\n * documentation and\/or other materials provided with the distribution.
\n *
\n * – Neither the name of Oracle or the names of its
\n * contributors may be used to endorse or promote products derived
\n * from this software without specific prior written permission.
\n *
\n * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS
\n * IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
\n * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
\n * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
\n * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
\n * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
\n * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
\n * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
\n * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
\n * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
\n * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
\n *\/<\/p>\n
package com.scoredev.scores;<\/p>\n
import java.io.*;
\nimport java.security.*;
\nimport java.util.Hashtable;<\/p>\n
public class HighScore
\n{
\n private String gameName;
\n private File highScoreFile;<\/p>\n
public HighScore(String gameName)
\n {
\n this.gameName = gameName;<\/p>\n
AccessController.doPrivileged(new PrivilegedAction() {
\n public Object run() {
\n String path =
\n System.getProperty(“user.home”) +
\n File.separator +
\n “.highscore”;<\/p>\n
highScoreFile = new File(path);
\n return null;
\n }
\n });
\n }<\/p>\n
public void setHighScore(final int score)
\n throws IOException
\n {
\n \/\/check permission first
\n SecurityManager sm = System.getSecurityManager();
\n if (sm != null) {
\n sm.checkPermission(new HighScorePermission(gameName));
\n }<\/p>\n
\/\/ need a doPrivileged block to manipulate the file
\n try {
\n AccessController.doPrivileged(new PrivilegedExceptionAction() {
\n public Object run() throws IOException {
\n Hashtable scores = null;
\n \/\/ try to open the existing file. Should have a locking
\n \/\/ protocol (could use File.createNewFile).
\n try {
\n FileInputStream fis =
\n new FileInputStream(highScoreFile);
\n ObjectInputStream ois = new ObjectInputStream(fis);
\n scores = (Hashtable) ois.readObject();
\n } catch (Exception e) {
\n \/\/ ignore, try and create new file
\n }<\/p>\n
\/\/ if scores is null, create a new hashtable
\n if (scores == null)
\n scores = new Hashtable(13);<\/p>\n
\/\/ update the score and save out the new high score
\n scores.put(gameName, new Integer(score));
\n FileOutputStream fos = new FileOutputStream(highScoreFile);
\n ObjectOutputStream oos = new ObjectOutputStream(fos);
\n oos.writeObject(scores);
\n oos.close();
\n return null;
\n }
\n });
\n } catch (PrivilegedActionException pae) {
\n throw (IOException) pae.getException();
\n }
\n }<\/p>\n
\/**
\n * get the high score. return -1 if it hasn’t been set.
\n *
\n *\/
\n public int getHighScore()
\n throws IOException, ClassNotFoundException
\n {
\n \/\/check permission first
\n SecurityManager sm = System.getSecurityManager();
\n if (sm != null) {
\n sm.checkPermission(new HighScorePermission(gameName));
\n }<\/p>\n
Integer score = null;<\/p>\n
\/\/ need a doPrivileged block to manipulate the file
\n try {
\n score = (Integer) AccessController.doPrivileged(
\n new PrivilegedExceptionAction() {
\n public Object run()
\n throws IOException, ClassNotFoundException
\n {
\n Hashtable scores = null;
\n \/\/ try to open the existing file. Should have a locking
\n \/\/ protocol (could use File.createNewFile).
\n FileInputStream fis =
\n new FileInputStream(highScoreFile);
\n ObjectInputStream ois = new ObjectInputStream(fis);
\n scores = (Hashtable) ois.readObject();<\/p>\n
\/\/ get the high score out
\n return scores.get(gameName);
\n }
\n });
\n } catch (PrivilegedActionException pae) {
\n Exception e = pae.getException();
\n if (e instanceof IOException)
\n throw (IOException) e;
\n else
\n throw (ClassNotFoundException) e;
\n }
\n if (score == null)
\n return -1;
\n else
\n return score.intValue();
\n }<\/p>\n
public static void main(String args[])
\n throws Exception
\n {
\n HighScore hs = new HighScore(args[1]);
\n if (args[0].equals(“set”)) {
\n hs.setHighScore(Integer.parseInt(args[2]));
\n } else {
\n System.out.println(“score = “+ hs.getHighScore());
\n }
\n }
\n}<\/p>\n
From: http:\/\/sitestree.com\/?p=10884
Categories:Root
Tags:
Post Data:2017-07-20 22:37:31<\/p>\n
\t\tShop Online: https:\/\/www.ShopForSoul.com\/<\/a> Implementing Your Own Permission 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(); } } … <\/p>\n
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