这里是用java写的一个计算器，用appllet的方式在浏览器中运行，如果电脑上装有java运行环境jre就能一试。将html代码保存为*.html(名称能够自定)，applettest编译为class文件放在同一文件夹下就能运行了。下面给出代码
applettest.html:
<html>
<head>
<title>CalculatorApplet</title>
</head>
<body>
<h1>CalculatorApplet</h1>
<h2>by:Carp_and_Wind</h2>
<applet code="applettest.class" width="400" height="400">
if your browser support java you would see javaapplet here.
</applet>
<br />
<a href="http://blog.csdn.net/Carp_and_Wind">My blog here to see the source code.</a>
</body>
</html>
applettest.java:
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class applettest extends JApplet
{
/**
* @param args
*/
public void init() {
EventQueue.invokeLater(new Runnable(){
public void run()
{
CalculatorPanel panel = new CalculatorPanel();//加入组件
add(panel);
}
});
}
}
/**
* A panel with calculator buttons and a result display.
*/
class CalculatorPanel extends JPanel//这个组建当中还能嵌套别的
{
public CalculatorPanel()
{
setLayout(new BorderLayout());
result = 0;
lastCommand = "=";
start = true;//初始化初始显示
// add the display
display = new JButton("0");
clear=new JButton("Clear");
display.setEnabled(false);
add(display, BorderLayout.NORTH);
ActionListener clearall = new ClearAction();
clear.addActionListener(clearall);
add(clear,BorderLayout.SOUTH);
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);//注意addbutton为自定义方法
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);
}
/**
* 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 ClearAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
start=true;
display.setText("0");
result = 0;
lastCommand = "=";
}
}
private class InsertAction implements ActionListener
{
public void actionPerformed(ActionEvent event)//event系统提供
{
String input = event.getActionCommand();
if (start)//why use start ?
{
display.setText("");//大概是初始化需要吧
start = false;
}
display.setText(display.getText() + input);
}
}
/**
* This action executes the command that the button action string denotes.
*/
private class CommandAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String command = event.getActionCommand();
if (start)//start什么用途？原来是用来表示第一计算顺序，这尼玛。。。够费心的！
{
if (command.equals("-"))
{
display.setText(command);
start = false;
}
else lastCommand = command;
}
else
{
calculate(Double.parseDouble(display.getText()));
lastCommand = command;
start = true;
}
}
}
/**
* 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;
display.setText("" + result);
}
private JButton clear;
private JButton display;
private JPanel panel;
private double result;
private String lastCommand;
private boolean start;
}