import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.io.*;
import java.net.*;
import javax.swing.text.*;
public class AWTBlockModels extends JFrame {
JButton blockButton, dontBlockButton;
JMenuItem blockMenuItem, dontBlockMenuItem, quitMenuItem;
JTextField urlField;
JTextArea contentArea;
final static String DEFAULT_URL =
"http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Component.html";
Thread loaderThread;
JProgressBar progressBar;
javax.swing.Timer progressBarUpdater;
public AWTBlockModels () {
super ("AWT Thread Blocking");
initMainLayout();
initMenus();
initActions();
}
private void initMainLayout() {
urlField = new JTextField (DEFAULT_URL, 60);
JPanel topPanel = new JPanel ();
topPanel.setLayout (new BoxLayout (topPanel, BoxLayout.Y_AXIS));
topPanel.add (urlField);
JPanel buttonPanel = new JPanel();
blockButton = new JButton ("Load (blocking)");
dontBlockButton = new JButton ("Load (non-blocking)");
buttonPanel.add (blockButton);
buttonPanel.add (dontBlockButton);
topPanel.add (buttonPanel);
contentArea = new JTextArea (25, 60);
JScrollPane scroller =
new JScrollPane (contentArea,
ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
getContentPane().setLayout(new BorderLayout());
getContentPane().add (topPanel, BorderLayout.NORTH);
getContentPane().add (scroller, BorderLayout.CENTER);
progressBar = new JProgressBar (0, 100);
getContentPane().add (progressBar, BorderLayout.SOUTH);
}
private void initMenus() {
JMenuBar bar = new JMenuBar();
JMenu fileMenu = new JMenu ("File");
blockMenuItem = new JMenuItem ("Load (blocking)");
dontBlockMenuItem = new JMenuItem ("Load (non-blocking)");
fileMenu.add (blockMenuItem);
fileMenu.add (dontBlockMenuItem);
fileMenu.addSeparator();
quitMenuItem = new JMenuItem ("Quit");
fileMenu.add (quitMenuItem);
bar.add (fileMenu);
setJMenuBar (bar);
}
private void initActions() {
quitMenuItem.addActionListener (new QuitAction());
BlockingLoadAction blocker = new BlockingLoadAction();
blockButton.addActionListener (blocker);
blockMenuItem.addActionListener (blocker);
NonBlockingLoadAction nonBlocker = new NonBlockingLoadAction();
dontBlockButton.addActionListener (nonBlocker);
dontBlockMenuItem.addActionListener (nonBlocker);
}
private void makeProgressBarUpdaterFor (NonBlockingURLDocument nbud) {
final NonBlockingURLDocument updatingDoc = nbud;
updateProgressBar (0);
ActionListener callback = new ActionListener() {
public void actionPerformed (ActionEvent ev) {
progressBar.setEnabled (true);
int progress = (int) (updatingDoc.getProgress() * 100);
updateProgressBar (progress);
if (! updatingDoc.isAlive())
progressBarUpdater.stop();
}
};
progressBarUpdater = new javax.swing.Timer (2000, callback);
progressBarUpdater.start();
}
private void updateProgressBar (int progress) {
// System.out.println ("update progress bar: " + progress);
if (progress > 0) {
progressBar.setValue (progress);
}
else
progressBar.setEnabled (false);
}
public static void main (String[] args) {
AWTBlockModels awtbm = new AWTBlockModels();
awtbm.pack();
awtbm.setVisible (true);
}
class QuitAction extends AbstractAction {
public void actionPerformed (ActionEvent e) {
System.exit(0);
}
}
class BlockingLoadAction extends AbstractAction {
public void actionPerformed (ActionEvent e) {
BlockingURLDocument bud =
new BlockingURLDocument (urlField.getText());
progressBar.setEnabled (true);
progressBar.setValue (0);
contentArea.setDocument (bud);
progressBar.setValue (100);
}
}
class NonBlockingLoadAction extends AbstractAction {
public void actionPerformed (ActionEvent e) {
NonBlockingURLDocument nbud =
new NonBlockingURLDocument (urlField.getText());
contentArea.setDocument (nbud);
makeProgressBarUpdaterFor (nbud);
}
}
class BlockingURLDocument extends PlainDocument {
public BlockingURLDocument (String urlString) {
super();
try {
URL url = new URL (urlField.getText());
BufferedReader in =
new BufferedReader (
new InputStreamReader (url.openStream()));
StringBuffer sbuf = new StringBuffer();
char[] buffy = new char [16 * 1024];
int bytesRead = 0;
while ((bytesRead = in.read (buffy, 0, buffy.length)) > -1) {
sbuf.append (buffy, 0, bytesRead);
// if your net connection is too fast to see blocking
// add the following here
// Thread.sleep (1000);
}
remove (0, getLength());
insertString (0, sbuf.toString(), null);
} catch (Exception e) {
CharArrayWriter writer = new CharArrayWriter();
e.printStackTrace (new PrintWriter (writer));
try {
remove (0, getLength());
insertString (0, writer.toString(), null);
} catch (Exception e2) {e2.printStackTrace();}
}
}
}
class NonBlockingURLDocument extends PlainDocument
implements Runnable {
protected int length = -1;
protected int totalBytesRead = 0;
protected String urlString;
protected Thread readThread;
public NonBlockingURLDocument (String urlString) {
super();
this.urlString = urlString;
// start thread here
readThread = new Thread (this);
readThread.start();
}
public void run() {
try {
remove (0, getLength());
URL url = new URL (urlField.getText());
URLConnection conn = url.openConnection();
length = conn.getContentLength();
System.out.println ("length is " + length);
BufferedReader in =
new BufferedReader (
new InputStreamReader (conn.getInputStream()));
// char[] buffy = new char [16 * 1024];
char[] buffy = new char [80];
totalBytesRead = 0;
int bytesRead = -1;
while ((bytesRead = in.read (buffy, 0, buffy.length)) > -1) {
final String str = new String (buffy, 0, bytesRead);
final int finalTBR = totalBytesRead;
Runnable worker = new Runnable () {
public void run() {
try {
insertString (finalTBR, str, null);
} catch (BadLocationException ble) {
ble.printStackTrace();
}
}
};
SwingUtilities.invokeLater (worker);
totalBytesRead += bytesRead;
System.out.println ("read " + totalBytesRead +
" of " + length +
", progress == " + getProgress());
// if your net connection is too fast to see updating,
// make buffy smaller above (maybe 512 bytes) and
// add the following here:
Thread.sleep (500);
}
} catch (Exception e) {
CharArrayWriter writer = new CharArrayWriter();
e.printStackTrace (new PrintWriter (writer));
try {
remove (0, getLength());
insertString (0, writer.toString(), null);
} catch (Exception e2) {e2.printStackTrace();}
} finally {
readThread = null;
}
}
public boolean isAlive() {
return (readThread != null) && (readThread.isAlive());
}
public float getProgress() {
return (float) totalBytesRead/length;
}
}
}
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