你试试这个: import java.awt.*; import java.awt.event.*; import java.io.*; import java.net.*; import javax.swing.*; import javax.swing.text.*; import javax.jnlp.*;/** A calculator with a calculation history that can be deployed as a Java Web Start application. */ public class WebStartCalculator { public static void main(String[] args) { CalculatorFrame frame = new CalculatorFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.show(); } }/** A frame with a calculator panel and a menu to load and save the calculator history. */ class CalculatorFrame extends JFrame { public CalculatorFrame() { setTitle(); Container contentPane = getContentPane(); panel = new CalculatorPanel(); contentPane.add(panel); JMenu fileMenu = new JMenu("File"); JMenuItem openItem = fileMenu.add("Open"); openItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { open(); } }); JMenuItem saveItem = fileMenu.add("Save"); saveItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { save(); } }); JMenuBar menuBar = new JMenuBar(); menuBar.add(fileMenu); setJMenuBar(menuBar);
pack(); }
/** Gets the title from the persistent store or asks the user for the title if there is no prior entry. */ public void setTitle() { try { String title = null; BasicService basic = (BasicService) ServiceManager.lookup("javax.jnlp.BasicService"); URL codeBase = basic.getCodeBase(); PersistenceService service = (PersistenceService) ServiceManager.lookup( "javax.jnlp.PersistenceService"); URL key = new URL(codeBase, "title"); try { FileContents contents = service.get(key); InputStream in = contents.getInputStream(); BufferedReader reader = new BufferedReader( new InputStreamReader(in)); title = reader.readLine(); } catch (FileNotFoundException exception) { title = JOptionPane.showInputDialog( "Please supply a frame title:"); if (title == null) return;
service.create(key, 100); FileContents contents = service.get(key); OutputStream out = contents.getOutputStream(true); PrintStream printOut = new PrintStream(out); printOut.print(title); setTitle(title); } setTitle(title); } catch (UnavailableServiceException exception) { JOptionPane.showMessageDialog(this, exception); } catch (MalformedURLException exception) { JOptionPane.showMessageDialog(this, exception); } catch (IOException exception) { JOptionPane.showMessageDialog(this, exception); } } /** Opens a history file and updates the display. */ public void open() { try { FileOpenService service = (FileOpenService) ServiceManager.lookup( "javax.jnlp.FileOpenService"); FileContents contents = service.openFileDialog(".", new String[] { "txt" }); JOptionPane.showMessageDialog(this, contents.getName()); if (contents != null) { InputStream in = contents.getInputStream(); BufferedReader reader = new BufferedReader( new InputStreamReader(in)); String line; while ((line = reader.readLine()) != null) { panel.append(line); panel.append("\n"); } } } catch (UnavailableServiceException exception) { JOptionPane.showMessageDialog(this, exception); } catch (IOException exception) { JOptionPane.showMessageDialog(this, exception); } } /** Saves the calculator history to a file. */ public void save() { try { ByteArrayOutputStream out = new ByteArrayOutputStream(); PrintStream printOut = new PrintStream(out); printOut.print(panel.getText()); InputStream data = new ByteArrayInputStream( out.toByteArray()); FileSaveService service = (FileSaveService) ServiceManager.lookup( "javax.jnlp.FileSaveService"); service.saveFileDialog(".", new String[] { "txt" }, data, "calc.txt"); } catch (UnavailableServiceException exception) { JOptionPane.showMessageDialog(this, exception); } catch (IOException exception) { JOptionPane.showMessageDialog(this, exception); } } private CalculatorPanel panel; } /** A panel with calculator buttons and a result display. */
class CalculatorPanel extends JPanel { /** Lays out the panel. */ public CalculatorPanel() { setLayout(new BorderLayout()); result = 0; lastCommand = "="; start = true;
// add the display display = new JTextArea(10, 20); add(new JScrollPane(display), BorderLayout.NORTH);
ActionListener insert = new InsertAction(); ActionListener command = new CommandAction(); // add the buttons in a 4 x 4 grid panel = new JPanel(); panel.setLayout(new GridLayout(4, 4)); addButton("7", insert); addButton("8", insert); addButton("9", insert); addButton("/", command); addButton("4", insert); addButton("5", insert); addButton("6", insert); addButton("*", command); addButton("1", insert); addButton("2", insert); addButton("3", insert); addButton("-", command); addButton("0", insert); addButton(".", insert); addButton("=", command); addButton("+", command); add(panel, BorderLayout.CENTER); } /** Gets the history text. @return the calculator history */ public String getText() { return display.getText(); }
/** Appends a string to the history text. @param s the string to append */ public void append(String s) { display.append(s); } /** Adds a button to the center panel. @param label the button label @param listener the button listener */ private void addButton(String label, ActionListener listener) { JButton button = new JButton(label); button.addActionListener(listener); panel.add(button); } /** This action inserts the button action string to the end of the display text. */ private class InsertAction implements ActionListener { public void actionPerformed(ActionEvent event) { String input = event.getActionCommand(); start = false; display.append(input); } } /** This action executes the command that the button action string denotes. */ private class CommandAction implements ActionListener { public void actionPerformed(ActionEvent evt) { String command = evt.getActionCommand(); if (start) { if (command.equals("-")) { display.append(command); start = false; } else lastCommand = command; } else { try { int lines = display.getLineCount(); int lineStart = display.getLineStartOffset(lines - 1); int lineEnd = display.getLineEndOffset(lines - 1); String value = display.getText(lineStart, lineEnd - lineStart); display.append(" "); display.append(command); calculate(Double.parseDouble(value)); if (command == "=") display.append("\n" + result); lastCommand = command; display.append("\n"); start = true; } catch (BadLocationException exception) { exception.printStackTrace(); } } } } /** Carries out the pending calculation. @param x the value to be accumulated with the prior result. */ public void calculate(double x) { if (lastCommand.equals("+")) result += x; else if (lastCommand.equals("-")) result -= x; else if (lastCommand.equals("*")) result *= x; else if (lastCommand.equals("/")) result /= x; else if (lastCommand.equals("=")) result = x; }
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import javax.swing.*;
import javax.swing.text.*;
import javax.jnlp.*;/**
A calculator with a calculation history that can be
deployed as a Java Web Start application.
*/
public class WebStartCalculator
{
public static void main(String[] args)
{
CalculatorFrame frame = new CalculatorFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.show();
}
}/**
A frame with a calculator panel and a menu to load and
save the calculator history.
*/
class CalculatorFrame extends JFrame
{
public CalculatorFrame()
{
setTitle();
Container contentPane = getContentPane();
panel = new CalculatorPanel();
contentPane.add(panel); JMenu fileMenu = new JMenu("File"); JMenuItem openItem = fileMenu.add("Open");
openItem.addActionListener(new
ActionListener()
{
public void actionPerformed(ActionEvent event)
{
open();
}
}); JMenuItem saveItem = fileMenu.add("Save");
saveItem.addActionListener(new
ActionListener()
{
public void actionPerformed(ActionEvent event)
{
save();
}
});
JMenuBar menuBar = new JMenuBar();
menuBar.add(fileMenu);
setJMenuBar(menuBar);
pack();
}
/**
Gets the title from the persistent store or
asks the user for the title if there is no prior entry.
*/
public void setTitle()
{
try
{
String title = null; BasicService basic = (BasicService)
ServiceManager.lookup("javax.jnlp.BasicService");
URL codeBase = basic.getCodeBase(); PersistenceService service = (PersistenceService)
ServiceManager.lookup(
"javax.jnlp.PersistenceService");
URL key = new URL(codeBase, "title"); try
{
FileContents contents = service.get(key);
InputStream in = contents.getInputStream();
BufferedReader reader = new BufferedReader(
new InputStreamReader(in));
title = reader.readLine();
}
catch (FileNotFoundException exception)
{
title = JOptionPane.showInputDialog(
"Please supply a frame title:");
if (title == null) return;
service.create(key, 100);
FileContents contents = service.get(key);
OutputStream out
= contents.getOutputStream(true);
PrintStream printOut = new PrintStream(out);
printOut.print(title);
setTitle(title);
}
setTitle(title);
}
catch (UnavailableServiceException exception)
{
JOptionPane.showMessageDialog(this, exception);
}
catch (MalformedURLException exception)
{
JOptionPane.showMessageDialog(this, exception);
}
catch (IOException exception)
{
JOptionPane.showMessageDialog(this, exception);
}
} /**
Opens a history file and updates the display.
*/
public void open()
{
try
{
FileOpenService service = (FileOpenService)
ServiceManager.lookup(
"javax.jnlp.FileOpenService");
FileContents contents = service.openFileDialog(".",
new String[] { "txt" }); JOptionPane.showMessageDialog(this, contents.getName());
if (contents != null)
{
InputStream in = contents.getInputStream();
BufferedReader reader = new BufferedReader(
new InputStreamReader(in));
String line;
while ((line = reader.readLine()) != null)
{
panel.append(line);
panel.append("\n");
}
}
}
catch (UnavailableServiceException exception)
{
JOptionPane.showMessageDialog(this, exception);
}
catch (IOException exception)
{
JOptionPane.showMessageDialog(this, exception);
}
} /**
Saves the calculator history to a file.
*/
public void save()
{
try
{
ByteArrayOutputStream out =
new ByteArrayOutputStream();
PrintStream printOut = new PrintStream(out);
printOut.print(panel.getText());
InputStream data = new ByteArrayInputStream(
out.toByteArray());
FileSaveService service = (FileSaveService)
ServiceManager.lookup(
"javax.jnlp.FileSaveService");
service.saveFileDialog(".",
new String[] { "txt" }, data, "calc.txt");
}
catch (UnavailableServiceException exception)
{
JOptionPane.showMessageDialog(this, exception);
}
catch (IOException exception)
{
JOptionPane.showMessageDialog(this, exception);
}
} private CalculatorPanel panel;
}
/**
A panel with calculator buttons and a result display.
*/
{
/**
Lays out the panel.
*/
public CalculatorPanel()
{
setLayout(new BorderLayout()); result = 0;
lastCommand = "=";
start = true;
// add the display display = new JTextArea(10, 20); add(new JScrollPane(display), BorderLayout.NORTH);
ActionListener insert = new InsertAction();
ActionListener command = new CommandAction(); // add the buttons in a 4 x 4 grid panel = new JPanel();
panel.setLayout(new GridLayout(4, 4)); addButton("7", insert);
addButton("8", insert);
addButton("9", insert);
addButton("/", command); addButton("4", insert);
addButton("5", insert);
addButton("6", insert);
addButton("*", command); addButton("1", insert);
addButton("2", insert);
addButton("3", insert);
addButton("-", command); addButton("0", insert);
addButton(".", insert);
addButton("=", command);
addButton("+", command); add(panel, BorderLayout.CENTER);
} /**
Gets the history text.
@return the calculator history
*/
public String getText()
{
return display.getText();
}
/**
Appends a string to the history text.
@param s the string to append
*/
public void append(String s)
{
display.append(s);
} /**
Adds a button to the center panel.
@param label the button label
@param listener the button listener
*/
private void addButton(String label, ActionListener listener)
{
JButton button = new JButton(label);
button.addActionListener(listener);
panel.add(button);
} /**
This action inserts the button action string to the
end of the display text.
*/
private class InsertAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String input = event.getActionCommand();
start = false;
display.append(input);
}
} /**
This action executes the command that the button
action string denotes.
*/
private class CommandAction implements ActionListener
{
public void actionPerformed(ActionEvent evt)
{
String command = evt.getActionCommand(); if (start)
{
if (command.equals("-"))
{
display.append(command);
start = false;
}
else
lastCommand = command;
}
else
{
try
{
int lines = display.getLineCount();
int lineStart
= display.getLineStartOffset(lines - 1);
int lineEnd
= display.getLineEndOffset(lines - 1);
String value = display.getText(lineStart,
lineEnd - lineStart);
display.append(" ");
display.append(command);
calculate(Double.parseDouble(value));
if (command == "=")
display.append("\n" + result);
lastCommand = command;
display.append("\n");
start = true;
}
catch (BadLocationException exception)
{
exception.printStackTrace();
}
}
}
} /**
Carries out the pending calculation.
@param x the value to be accumulated with the prior result.
*/
public void calculate(double x)
{
if (lastCommand.equals("+")) result += x;
else if (lastCommand.equals("-")) result -= x;
else if (lastCommand.equals("*")) result *= x;
else if (lastCommand.equals("/")) result /= x;
else if (lastCommand.equals("=")) result = x;
}
private JTextArea display;
private JPanel panel;
private double result;
private String lastCommand;
private boolean start;
}
import javax.jnlp.*查找不到!
怎么办呀!急!
good luck