苹果公司侦听器 [英] JApplet & KeyListener
问题描述
我正在为我的计算机科学课程开发一个应用程序.任务是编写一个计算器,但不使用JTextField
s或JTextArea
s.我想出了实现KeyListener
的想法,该实现在appletviewer和JFrame
中都很好,但在Google Chrome浏览器中(可能还有其他浏览器)根本不起作用.
I'm developing an application for my computer science classes. The task is to write a calculator but without using JTextField
s or JTextArea
s. I've come up with an idea of implementing KeyListener
which works nice in both appletviewer and JFrame
but doesn't work at all in Google Chrome (and probably other browsers).
这是我的代码段.
//- BinaryCalc.java
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
public class BinaryCalc extends JApplet implements KeyListener {
private JPanel panel;
public BinaryCalc() {
super();
panel = new JPanel();
this.add(panel);
panel.addKeyListener(this);
panel.requestFocusInWindow();
}
@Override
public void init() {
JOptionPane.showMessageDialog(this, "applet");
panel.setFocusable(true);
panel.requestFocus();
}
public void keyPressed(KeyEvent e) {
JOptionPane.showMessageDialog(this, (char) e.getKeyCode());
}
public void keyReleased(KeyEvent e) {}
public void keyTyped(KeyEvent e) {}
public JPanel getPanel() { return panel; }
public static void main(String args[]) {
JFrame frame = new JFrame("Binary Calculator");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setMinimumSize(new Dimension(320, 240));
BinaryCalc kalkulator = new BinaryCalc();
frame.add(kalkulator);
frame.pack();
frame.setVisible(true);
kalkulator.getPanel().requestFocusInWindow();
}
}
还有包含我的applet的HTML文件.
And HTML file containing my applet.
<!doctype html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" type="text/css" href="style.css">
<title>Kalkulator binarny</title>
</head>
<body>
<div style="text-align: center; border-bottom: 1px solid black">
<h1>Kalkulator Binarny</h1>
</div>
<br/>
<object style="display: block; margin: auto;" type="application/x-java-applet" width="320" height="240">
<param name="code" value="BinaryCalc.class" />
<!--- <param name="archive" value="Liczba.jar" /> -->
What a terrible failure: applet failed to load!
</object>
<br/>
</body>
</html>
有什么想法吗?
推荐答案
我很随意地将@David的有用示例转换为使用标签和数字小键盘.
I took the liberty of converting @David's helpful example to use a label and the numeric keypad.
更新:此混合可在Ubuntu/OpenJDK上运行,并且可以通过Java Web Start .
Update: This hybrid works on Ubuntu/OpenJDK, and it can be deployed via Java Web Start.
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.event.*;
import javax.swing.*;
/**
* @see https://stackoverflow.com/a/13363349/230513
*/
public class BinaryCalc extends JApplet {
private static BinaryCalc bc = new BinaryCalc();
private JLabel label = new JLabel("0000000000");
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame();
frame.setTitle("BinaryCalc");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
initContainer(frame);
frame.pack();
bc.label.setText("");
frame.setVisible(true);
}
});
}
// Common initialization for either JApplet or JFrame
private static void initContainer(Container container) {
JPanel panel = new JPanel();
bc.setKeyBindings(panel);
panel.add(bc.label);
container.add(panel, BorderLayout.CENTER);
panel.requestFocusInWindow();
}
@Override
public void init() {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
initContainer(BinaryCalc.this);
}
});
}
private void setKeyBindings(final JPanel panel) {
panel.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
.put(KeyStroke.getKeyStroke(KeyEvent.VK_0, 0), "0");
panel.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
.put(KeyStroke.getKeyStroke(KeyEvent.VK_NUMPAD0, 0), "0");
panel.getActionMap().put("0", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent ae) {
String tmp = label.getText();
label.setText(tmp + "0");
}
});
panel.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
.put(KeyStroke.getKeyStroke(KeyEvent.VK_1, 0), "1");
panel.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
.put(KeyStroke.getKeyStroke(KeyEvent.VK_NUMPAD1, 0), "1");
panel.getActionMap().put("1", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent ae) {
String tmp = label.getText();
label.setText(tmp + "1");
}
});
}
}
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