java中，用布局器实现计算器界面 并实现加减乘除等功能，怎样编程

java写的，可行

package ex1;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;

import javax.swing.BorderFactory;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.JTextField;

public class Calcutor extends JFrame {
private JTextField tf;
private JPanel panel1, panel2, panel3, panel4;
private JMenuBar myBar;
private JMenu menu1, menu2, menu3;
private JMenuItem editItem1, editItem2, help1, help2, help3;
private JRadioButtonMenuItem seeItem1, seeItem2;//单选框
private JCheckBoxMenuItem seeItem3;//复选框
private ButtonGroup bgb;
private String back;
private boolean IfResult = true, flag = false;
private String oper = "=";
private double result = 0;
private Num numActionListener;
private DecimalFormat df;

public Calcutor(){
super("科学计算器");//设置标题栏

df = new DecimalFormat("#.####");//保留四位小数

this.setLayout(new BorderLayout(10, 5));
panel1 = new JPanel(new GridLayout(1, 3, 10, 10));
panel2 = new JPanel(new GridLayout(5, 6, 5, 5));//5行6列
panel3 = new JPanel(new GridLayout(5, 1, 5, 5));
panel4 = new JPanel(new BorderLayout(5, 5));

/**
* 菜单栏
*/
myBar = new JMenuBar();
menu1 = new JMenu("编辑(E)");
menu2 = new JMenu("查看(V)");
menu3 = new JMenu("帮助(H)");

menu1.setFont(new Font("宋体", Font.PLAIN, 12));
menu2.setFont(new Font("宋体", Font.PLAIN, 12));
menu3.setFont(new Font("宋体", Font.PLAIN, 12));

/**
* 编辑栏
*/
editItem1 = new JMenuItem("复制(C) Ctrl+C");
editItem2 = new JMenuItem("粘贴(P) Ctrl+V");

editItem1.setFont(new Font("宋体",Font.PLAIN,12));
editItem2.setFont(new Font("宋体",Font.PLAIN,12));

/**
* 查看栏
*/
seeItem1 = new JRadioButtonMenuItem("科学型(T)");
seeItem2 = new JRadioButtonMenuItem("标准型(S)");
seeItem3 = new JCheckBoxMenuItem("数字分组(I)");

seeItem1.setFont(new Font("宋体",Font.PLAIN,12));
seeItem2.setFont(new Font("宋体",Font.PLAIN,12));
seeItem3.setFont(new Font("宋体",Font.PLAIN,12));

/**
* 帮助栏
*/
help1 = new JMenuItem("帮助主题(H)");
help2 = new JMenuItem("关于计算器(A)");

help1.setFont(new Font("宋体",Font.PLAIN,12));
help2.setFont(new Font("宋体",Font.PLAIN,12));

bgb = new ButtonGroup();//选项组

menu1.add(editItem1);
menu1.add(editItem2);

menu2.add(seeItem1);
menu2.add(seeItem2);
menu2.addSeparator();//添加一条分割线
menu2.add(seeItem3);

menu3.add(help1);
menu3.addSeparator();//添加一条分割线
menu3.add(help2);

myBar.add(menu1);
myBar.add(menu2);
myBar.add(menu3);

this.setJMenuBar(myBar);

numActionListener = new Num();//实现数字监听

/**
* 文本域，即为计算器的屏幕显示区域
*/
tf = new JTextField();
tf.setEditable(false);//文本区域不可编辑
tf.setBackground(Color.white);//文本区域的背景色
tf.setHorizontalAlignment(JTextField.RIGHT);//文字右对齐
tf.setText("0");
tf.setBorder(BorderFactory.createLoweredBevelBorder());
init();//对计算器进行初始化

}
/**
* 初始化操作
* 添加按钮
*/
private void init(){
addButton(panel1, "Backspace", new Clear(), Color.red);
addButton(panel1, "CE", new Clear(), Color.red);
addButton(panel1, "C", new Clear(), Color.red);

addButton(panel2, "1/x", new Signs(), Color.magenta);
addButton(panel2, "log", new Signs(), Color.magenta);
addButton(panel2, "7", numActionListener, Color.blue);
addButton(panel2, "8", numActionListener, Color.blue);
addButton(panel2, "9", numActionListener, Color.blue);
addButton(panel2, "÷", new Signs(), Color.red);

addButton(panel2, "n!", new Signs(), Color.magenta);
addButton(panel2, "sqrt", new Signs(), Color.magenta);
addButton(panel2, "4", numActionListener, Color.blue);
addButton(panel2, "5", numActionListener, Color.blue);
addButton(panel2, "6", numActionListener, Color.blue);
addButton(panel2, "×", new Signs(), Color.red);

addButton(panel2, "sin", new Signs(), Color.magenta);
addButton(panel2, "x^2", new Signs(), Color.magenta);
addButton(panel2, "1", numActionListener, Color.blue);
addButton(panel2, "2", numActionListener, Color.blue);
addButton(panel2, "3", numActionListener, Color.blue);
addButton(panel2, "-", new Signs(), Color.red);

addButton(panel2, "cos", new Signs(), Color.magenta);
addButton(panel2, "x^3", new Signs(), Color.magenta);
addButton(panel2, "0", numActionListener, Color.blue);
addButton(panel2, "-/+", new Clear(), Color.blue);
addButton(panel2, ".", new Dot(), Color.blue);
addButton(panel2, "+", new Signs(), Color.red);

addButton(panel2, "tan", new Signs(), Color.magenta);
addButton(panel2, "%", new Signs(), Color.magenta);
addButton(panel2, "π", numActionListener, Color.orange);
addButton(panel2, "e", numActionListener, Color.orange);
addButton(panel2, "′″", new Signs(), Color.orange);
addButton(panel2, "=", new Signs(), Color.red);

JButton btns = new JButton("计算器");
btns.setBorder(BorderFactory.createLoweredBevelBorder());
btns.setEnabled(false);//按钮不可操作
btns.setPreferredSize(new Dimension(20, 20));

panel3.add(btns);//加入按钮
addButton(panel3, "MC", null, Color.red);
addButton(panel3, "MR", null, Color.red);
addButton(panel3, "MS", null, Color.red);
addButton(panel3, "M+", null, Color.red);

panel4.add(panel1, BorderLayout.NORTH);
panel4.add(panel2, BorderLayout.CENTER);
this.add(tf, BorderLayout.NORTH);
this.add(panel3, BorderLayout.WEST);
this.add(panel4);

pack();
this.setResizable(false);//窗口不可改变大小
this.setLocation(300, 200);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
/**
* 统一设置按钮的的使用方式
* @param panel
* @param name
* @param action
* @param color
*/
private void addButton(JPanel panel, String name, ActionListener action, Color color){
JButton bt = new JButton(name);
panel.add(bt);//在面板上增加按钮
bt.setForeground(color);//设置前景（字体）颜色
bt.addActionListener(action);//增加监听事件
}
/**
* 计算器的基础操作（+ - × ÷）
* @param x
*/
private void getResult (double x){
if(oper == "+"){result += x;}
else if(oper == "-"){result -= x;}
else if(oper == "×"){result *= x;}
else if(oper == "÷"){result /= x;}
else if(oper == "="){result = x;}
tf.setText(df.format(result));
}
/**
* 运算符号的事件监听
*/
class Signs implements ActionListener{
public void actionPerformed(ActionEvent e) {
/*
* 用ActionEvent对象的getActionCommand()方法
* 取得与引发事件对象相关的字符串
*/
String str = e.getActionCommand();

/* sqrt求平方根 */
if(str.equals("sqrt")){
double i = Double.parseDouble(tf.getText());
if(i>=0){
/*
* String.valueOf() 转换为字符串
* df.format() 按要求保留四位小数
* Math.sqrt() 求算数平方根
*/
tf.setText(String.valueOf(df.format(Math.sqrt(i))));
}
else{
tf.setText("负数不能开平方根");
}
}

/* log求常用对数 */
else if(str.equals("log")){
double i = Double.parseDouble(tf.getText());
if(i>0){
tf.setText(String.valueOf(df.format(Math.log(i))));
}else{
tf.setText("负数不能求对数");
}
}

/* %求百分比 */
else if(str.equals("%")){
tf.setText(df.format(Double.parseDouble(tf.getText()) / 100));
}

/* 1/x求倒数 */
else if(str.equals("1/x")){
if(Double.parseDouble(tf.getText()) == 0){
tf.setText("除数不能为零");
}else{
tf.setText(df.format(1 / Double.parseDouble(tf.getText())));
}
}

/* sin求正弦函数 */
else if(str.equals("sin")){
double i = Double.parseDouble(tf.getText());
tf.setText(String.valueOf(df.format(Math.sin(i))));
}

/* cos求余弦函数 */
else if(str.equals("cos")){
double i = Double.parseDouble(tf.getText());
tf.setText(String.valueOf(df.format(Math.cos(i))));
}

/* tan求正切函数 */
else if(str.equals("tan")){
double i = Double.parseDouble(tf.getText());
tf.setText(String.valueOf(df.format(Math.tan(i))));
}

/* n!求阶乘 */
else if(str.equals("n!")){
double i = Double.parseDouble(tf.getText());
if((i%2==0)||(i%2==1))//判断为整数放进行阶乘操作
{
int j = (int)i;//强制类型转换
int result=1;
for(int k=1;k<=j;k++)
result *= k;
tf.setText(String.valueOf(result));
}
else
{
tf.setText("无法进行阶乘");
}
}

/* x^2求平方 */
else if(str.equals("x^2")){
double i = Double.parseDouble(tf.getText());
tf.setText(String.valueOf(df.format(i*i)));
}

/* x^3求立方 */
else if(str.equals("x^3")){
double i = Double.parseDouble(tf.getText());
tf.setText(String.valueOf(df.format(i*i*i)));
}

/* ′″角度转换 */
/**
* 将角度值转换成弧度值，方便三角函数的计算
*/
else if(str.equals("′″")){
double i = Double.parseDouble(tf.getText());
tf.setText(String.valueOf(i/180*Math.PI));
}

else{
if(flag){
IfResult = false;
}
if(IfResult){
oper = str;
}else{
getResult(Double.parseDouble(tf.getText()));
oper = str;
IfResult = true;
}
}
}
}
/**
* 清除按钮的事件监听
*/
class Clear implements ActionListener{
public void actionPerformed(ActionEvent e) {
/*
* 用ActionEvent对象的getActionCommand()方法
* 取得与引发事件对象相关的字符串
*/
String str = e.getActionCommand();
if(str == "C"){
tf.setText("0");
IfResult = true;
result = 0;
}else if(str == "-/+"){
double i = 0 - Double.parseDouble(tf.getText().trim());
tf.setText(df.format(i));
}else if(str == "Backspace"){
if(Double.parseDouble(tf.getText()) > 0){
if(tf.getText().length() > 1){
tf.setText(tf.getText().substring(0, tf.getText().length() - 1));
//使用退格删除最后一位字符
}else{
tf.setText("0");
IfResult = true;
}
}else{
if(tf.getText().length() > 2){
tf.setText(tf.getText().substring(0, tf.getText().length() - 1));
}else{
tf.setText("0");
IfResult = true;
}
}
}else if(str == "CE"){
tf.setText("0");
IfResult = true;
}
}
}
/**
* 数字输入的事件监听
*/
class Num implements ActionListener{
public void actionPerformed(ActionEvent e) {
String str = e.getActionCommand();
if(IfResult){
tf.setText("");
IfResult = false;
}
if(str=="π")
{
tf.setText(String.valueOf(Math.PI));
}
else if(str=="e")
{
tf.setText(String.valueOf(Math.E));
}
else{
tf.setText(tf.getText().trim() + str);
if(tf.getText().equals("0")){
tf.setText("0");
IfResult = true;
flag = true;
}
}
}
}
/**
* 小数点的事件监听
*/
class Dot implements ActionListener{
public void actionPerformed(ActionEvent e) {
IfResult = false;
if(tf.getText().trim().indexOf(".") == -1){
tf.setText(tf.getText() + ".");
}
}
}
/**
* main方法
*/
public static void main(String[] args) {
new Calcutor().setVisible(true);
}
}