/*
* Copyright (c) 1996-1999 Bill Venners. All Rights Reserved.
*
* This Java source file is part of the Interactive Illustrations Web
* Site, which is delivered in the applets directory of the CD-ROM
* that accompanies the book "Inside the Java 2 Virtual Machine" by Bill
* Venners, published by McGraw-Hill, 1999, ISBN: 0-07-135093-4. This
* source file is provided for evaluation purposes only, but you can
* redistribute it under certain conditions, described in the full
* copyright notice below.
*
* Full Copyright Notice:
*
* All the web pages and Java applets delivered in the applets
* directory of the CD-ROM, consisting of ".html," ".gif," ".class,"
* and ".java" files, are copyrighted (c) 1996-1999 by Bill
* Venners, and all rights are reserved. This material may be copied
* and placed on any commercial or non-commercial web server on any
* network (including the internet) provided that the following
* guidelines are followed:
*
* a. All the web pages and Java Applets (".html," ".gif," ".class,"
* and ".java" files), including the source code, that are delivered
* in the applets directory of the CD-ROM that
* accompanies the book must be published together on the same web
* site.
*
* b. All the web pages and Java Applets (".html," ".gif," ".class,"
* and ".java" files) must be published "as is" and may not be altered
* in any way.
*
* c. All use and access to this web site must be free, and no fees
* can be charged to view these materials, unless express written
* permission is obtained from Bill Venners.
*
* d. The web pages and Java Applets may not be distributed on any
* media, other than a web server on a network, and may not accompany
* any book or publication.
*
* BILL VENNERS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE
* SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR PARTICULAR PURPOSE, OR NON-INFRINGEMENT. BILL VENNERS
* SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY A LICENSEE AS A
* RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES.
*/
import java.awt.*;
import java.applet.*;
import java.io.InputStream;
import java.io.DataInputStream;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.EOFException;
import java.net.URL;
import java.net.URLConnection;
import java.net.MalformedURLException;
/**
* This applet describes the contents of a particular a Java class
* file as it is loaded, one chunk of bytes at a time, by the JVM.
*
* @author Bill Venners
*/
public class GettingLoaded extends Applet
implements Runnable {
private URL theClassFileURL;
private URL theActTextURL;
private Thread runner;
private TextArea ta = new TextArea();
private StepNode firstNode;
private StepNode lastNode;
private StepNode currentNode;
private boolean ready = false;
private boolean jvmFinishedGobbling = false;
private int currentGobblePosition = 0;
private JVMPacman jvmPacman;
private String titleString = "Getting Loaded\n\n";
private boolean urlExceptionWasThrown = false;
private String cantGoFurtherString = "Unfortunately this means the applet cannot go any further.\n";
private String ioErrorMsg = "An IO Error occured while trying to read a file from the server.\n";
private String securityErrorMsg = "An security exception occured while trying to read a file from the server.\n";
private String urlErrorMsg = "This HTML file contains a malformed URL of a file required by this applet.\n";
public void init() {
super.init();
ta.setEditable(false);
setBackground(Color.blue);
String url = getParameter("classURL");
try {
this.theClassFileURL = new URL(getDocumentBase(), url);
}
catch (MalformedURLException e) {
urlExceptionWasThrown = true;
URL docBase = getDocumentBase();
ta.setText(titleString + "Bad URL: " + docBase.toString() + url + "\n\n" + urlErrorMsg + cantGoFurtherString);
}
url = getParameter("textURL");
try {
this.theActTextURL = new URL(getDocumentBase(), url);
}
catch (MalformedURLException e) {
urlExceptionWasThrown = true;
URL docBase = getDocumentBase();
ta.setText(titleString + "Bad URL: " + docBase.toString() + url + "\n\n" + urlErrorMsg + cantGoFurtherString);
}
ControlPanel controlPanel = new ControlPanel();
jvmPacman = controlPanel.getJVMPacman();
setLayout(new BorderLayout(5, 5));
ta.setBackground(Color.white);
add("North", new ColoredLabel("GETTING LOADED", Label.CENTER, Color.cyan));
add("South", controlPanel);
add("Center", ta);
}
public boolean handleEvent(Event event) {
return super.handleEvent(event);
}
public boolean action(Event evt, Object arg) {
if (evt.target instanceof Button) {
String bname = (String) arg;
if (bname.equals("Reset")) {
if (ready) {
if (!currentNode.first()) {
currentNode = firstNode;
currentGobblePosition = 0;
jvmPacman.setGobblePosition(0, currentNode.getByteCount());
ta.setText(currentNode.getString());
}
}
}
else if (bname.equals("Step")) {
if (ready) {
if (!currentNode.last()) {
currentGobblePosition += currentNode.getByteCount();
currentNode = currentNode.getNext();
jvmPacman.gobbleToPosition(currentGobblePosition, currentNode.getByteCount());
ta.setText(currentNode.getString());
}
else {
if (!jvmFinishedGobbling) {
currentGobblePosition += currentNode.getByteCount();
jvmPacman.gobbleToPosition(currentGobblePosition, 0);
jvmFinishedGobbling = true;
ta.setText("(The End)");
}
}
}
}
else if (bname.equals("Back")) {
if (ready) {
if (!currentNode.first()) {
if (jvmFinishedGobbling) {
jvmFinishedGobbling = false;
currentGobblePosition -= currentNode.getByteCount();
}
else {
currentNode = currentNode.getPrev();
currentGobblePosition -= currentNode.getByteCount();
}
jvmPacman.setGobblePosition(currentGobblePosition, currentNode.getByteCount());
ta.setText(currentNode.getString());
}
}
}
}
return true;
}
public Insets insets() {
return new Insets(5, 5, 5, 5);
}
public void start() {
if (runner == null && !ready && !urlExceptionWasThrown) {
runner = new Thread (this);
runner.start();
}
}
public void stop() {
if (runner != null) {
runner.stop();
runner = null;
}
}
public void run() {
InputStream conn = null;
DataInputStream data = null;
String line;
StringBuffer buf = new StringBuffer();
ta.setText(titleString + "Loading First Of Two Files...\n");
try {
conn = this.theClassFileURL.openStream();
data = new DataInputStream(new BufferedInputStream(conn));
try {
while (true) {
int unsignedByte = data.readUnsignedByte();
HexString hexStr = new HexString(unsignedByte, 2);
buf.append(hexStr.getString());
}
}
catch (EOFException e) {
jvmPacman.setText(buf.toString());
}
try {
ta.setText(titleString + "Loading Second Of Two Files...\n");
conn = this.theActTextURL.openStream();
data = new DataInputStream(new BufferedInputStream(conn));
buf.setLength(0);
while ((line = data.readLine()) != null) {
if (line.length() > 0 && line.charAt(0) == '*') {
int starCount = line.length();
StepNode nextNode = new StepNode(buf.toString(), starCount);
if (firstNode == null) {
firstNode = nextNode;
lastNode = nextNode;
}
else {
lastNode.setNext(nextNode);
nextNode.setPrev(lastNode);
lastNode = nextNode;
}
buf.setLength(0);
}
else {
buf.append(line + "\n");
}
}
ready = true;
currentNode = firstNode;
jvmPacman.setGobblePosition(0, firstNode.getByteCount());
ta.setText(currentNode.getString());
}
catch (IOException e) {
ta.setText(titleString + "IO Error: " + e.getMessage() + "\n\n"
+ ioErrorMsg + cantGoFurtherString);
}
catch (SecurityException e) {
ta.setText(titleString + "Security Exception: " + e.getMessage() + "\n\n"
+ securityErrorMsg + cantGoFurtherString);
}
}
catch (IOException e) {
ta.setText(titleString + "IO Error: " + e.getMessage() + "\n\n"
+ ioErrorMsg + cantGoFurtherString);
}
catch (SecurityException e) {
ta.setText(titleString + "Security Exception: " + e.getMessage() + "\n\n"
+ securityErrorMsg + cantGoFurtherString);
}
finally {
runner = null;
}
}
}