计算器如何实现键盘输入？（附计算器代码）

public class Calculator extends JFrame implements ActionListener {

	

	// 定义计算器显示框

	public JTextField jtf, jtf2;

	// 定义0-9按键

	public Btn btnE, btn0, btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8,

			btn9, btnP, btnM, btnX, btnD, C, btnPO, btnA;

	// 定义数字面板,操作符面板

	public JPanel numP, numP1, numP2, showP, opP, opP1, opP2;

	// 定义计算的中间变量

	static double num1, num2, num3, result;

	// 定义操作符

	char opPerator;

	boolean next = false;

	static boolean flagE = false;// 监督是否按了等号

	static boolean isDot = false;// 监督是否按了小数点

	static String s = "=", str1, str2, newS, oldS;// 定义变量 创建对像

	// TextField txt;

	// UndoManager um=new UndoManager();

	public JMenuBar jmb;

	public JMenu jm;

	private JMenuItem SCal, Cal, Exit;



	public Calculator() {

		

		super("普通计算器");

		// 布局

		setSize(480, 357);// setSize(309, 345);

		setLocation(700, 100);

		Container c = this.getContentPane();

		BorderLayout bL = new BorderLayout();

		c.setLayout(bL);

		jmb = new JMenuBar();

		setJMenuBar(jmb);

		SCal = new JMenuItem("科学计算器");

		Cal = new JMenuItem("普通计算器");

		Exit = new JMenuItem("退出(Q)");

		Exit.setMnemonic('Q');

		Exit.addActionListener(new ActionListener() {

			public void actionPerformed(ActionEvent event) {

				System.exit(0);

			}

		});

		jm = new JMenu("编辑");

		jm.add(Cal);

		jm.add(SCal);

		jm.add(Exit);

		jmb.add(jm);

		showP = new JPanel();

		opP = new JPanel();

		opP1 = new JPanel();

		opP2 = new JPanel();

		numP = new JPanel();

		numP1 = new JPanel();

		numP2 = new JPanel();



		showP.setLayout(new BorderLayout());

		opP.setLayout(new BorderLayout());

		opP1.setLayout(new GridLayout(3, 2, 2, 2));

		opP2.setLayout(new BorderLayout());

		numP.setLayout(new BorderLayout());

		numP1.setLayout(new GridLayout(3, 3, 2, 2));

		numP2.setLayout(new GridLayout(1, 2, 2, 2));

		Font font = new Font("New Roma Times", Font.BOLD, 30);



		jtf2 = new JTextField("0");

		jtf = new JTextField("0");

		jtf.setFont(font);

		jtf.setEditable(false);//jtf设置不可编辑

		jtf2.setEditable(false);

		

		showP.add(jtf2, BorderLayout.NORTH);

		showP.add(jtf, BorderLayout.CENTER);

		jtf2.setHorizontalAlignment(jtf2.RIGHT);

		jtf.setHorizontalAlignment(jtf.RIGHT);

		c.add(showP, BorderLayout.NORTH);

		

	         	 /************创建对象***********/

		

		btn9 = new Btn("9");

		btn8 = new Btn("8");

		btn7 = new Btn("7");

		btn6 = new Btn("6");

		btn5 = new Btn("5");

		btn4 = new Btn("4");

		btn3 = new Btn("3");

		btn2 = new Btn("2");

		btn1 = new Btn("1");

		btn0 = new Btn("0");

		btnPO = new Btn(".");

		C = new Btn("C");

		btnA = new Btn("←");

		btnP = new Btn("+");

		btnM = new Btn("-");

		btnX = new Btn("*");

		btnD = new Btn("/");

		btnE = new Btn("=");

		

		         /************设置按钮外观*********/

		

		btn9.setFont(font);

		btn9.setForeground(Color.white);

		btn8.setFont(font);

		btn8.setForeground(Color.white);

		btn6.setFont(font);

		btn6.setForeground(Color.white);

		btn7.setFont(font);

		btn7.setForeground(Color.white);

		btn5.setFont(font);

		btn5.setForeground(Color.white);

		btn4.setFont(font);

		btn4.setForeground(Color.white);

		btn3.setFont(font);

		btn3.setForeground(Color.white);

		btn2.setFont(font);

		btn2.setForeground(Color.white);

		btn1.setFont(font);

		btn1.setForeground(Color.white);

		btn0.setFont(font);

		btn0.setForeground(Color.white);

		btnPO.setFont(font);

		btnPO.setForeground(Color.cyan);

		C.setFont(font);

		C.setForeground(Color.cyan);

		btnA.setFont(font);

		btnA.setForeground(Color.cyan);

		btnP.setFont(font);

		btnP.setForeground(Color.cyan);

		btnM.setFont(font);

		btnM.setForeground(Color.cyan);

		btnX.setFont(font);

		btnX.setForeground(Color.cyan);

		btnD.setFont(font);

		btnD.setForeground(Color.cyan);

		btnE.setFont(font);

		btnE.setForeground(Color.cyan);

		btnE.setEnabled(false);

		

		           /************按钮添加到面板***************/

		

		numP1.add(btn7);

		numP1.add(btn8);

		numP1.add(btn9);

		numP1.add(btn4);

		numP1.add(btn5);

		numP1.add(btn6);

		numP1.add(btn1);

		numP1.add(btn2);

		numP1.add(btn3);

		numP.add(numP1, BorderLayout.NORTH);//1-9

		

		numP2.add(btn0);//0

		numP2.add(btnPO);//小数点

		numP.add(numP2, BorderLayout.SOUTH);

		

		c.add(numP, BorderLayout.WEST);

		

		opP1.add(C);//复原 

		opP1.add(btnA);//撤消

		opP1.add(btnP);//加号

		opP1.add(btnM);//减号

		opP1.add(btnX);//乘号

		opP1.add(btnD);//除号

		opP.add(opP1, BorderLayout.NORTH);

		

		opP2.add(btnE);//等号

		opP.add(opP2, BorderLayout.SOUTH);

		

		c.add(opP, BorderLayout.EAST);

		this.setResizable(false);

		

		

		

		/************添加监听器*******************/

		

		btn0.addActionListener(this);

		btn1.addActionListener(this);

		btn2.addActionListener(this);

		btn3.addActionListener(this);

		btn4.addActionListener(this);

		btn5.addActionListener(this);

		btn6.addActionListener(this);

		btn7.addActionListener(this);

		btn8.addActionListener(this);

		btn9.addActionListener(this);

		btnP.addActionListener(this);

		btnM.addActionListener(this);

		btnX.addActionListener(this);

		btnD.addActionListener(this);

		btnE.addActionListener(this);

		btnPO.addActionListener(this);

		btnA.addActionListener(this);

		C.addActionListener(this);

		SCal.addActionListener(this);

	}



	public void actionPerformed(ActionEvent e) {

//代码太长发不了，这里就不加入了

		}

｝