java实现计算器的代码

//界面实现计算器

package com.hushi.calculator;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.text.DecimalFormat;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

import sun.print.resources.serviceui;


public class Calculator {
    //计算器面板
 private JFrame f = new JFrame("我的计算器");
 
 //输入面扳
 private JPanel inputPanel = new JPanel();
 //加减乘除面板
 private JPanel operationPanel = new JPanel();
 //数字面板
 private JPanel buttonsPanel = new JPanel();
 
 //输入数据文本框
 private JTextField input = new JTextField(20);
 
 //退格键
 private JButton backspace = new JButton("BackSpace");
 //清空
 private JButton CE = new JButton("CE  ");
 //删除
 private JButton C = new JButton("C  ");
 
 //四则运算符号键
 private JButton add = new JButton("+");
 private JButton sub = new JButton("-");
 private JButton mul = new JButton("*");
 private JButton div = new JButton("/");
 
 //小数点
 private JButton decimal = new JButton(".");
 //等号
 private JButton equal = new JButton("=");
 
 //数字键
 private JButton zero = new JButton("0");
 private JButton one = new JButton("1");
 private JButton two = new JButton("2");
 private JButton three = new JButton("3");
 private JButton four = new JButton("4");
 private JButton five = new JButton("5");
 private JButton six = new JButton("6");
 private JButton seven = new JButton("7");
 private JButton eight = new JButton("8");
 private JButton nine = new JButton("9");
 
 private String num1 = "";//保存第一个运算数字
 private String operator = "";//保存运算符号
 
 public static void main(String[] args) {
  new Calculator();//new计算器实例
 }
 
 public Calculator(){
      //添加组件，布局
  inputPanel.add(input);
  f.add(inputPanel, BorderLayout.NORTH);
  
  operationPanel.add(backspace);
  operationPanel.add(CE);
  operationPanel.add(C);
  f.add(operationPanel, BorderLayout.CENTER);
  
  buttonsPanel.add(add);
  buttonsPanel.add(sub);
  buttonsPanel.add(mul);
  buttonsPanel.add(div);
  buttonsPanel.add(one);
  buttonsPanel.add(two);
  buttonsPanel.add(three);
  buttonsPanel.add(zero);
  buttonsPanel.add(four);
  buttonsPanel.add(five);
  buttonsPanel.add(six);
  buttonsPanel.add(decimal);
  buttonsPanel.add(seven);
  buttonsPanel.add(eight);
  buttonsPanel.add(nine);
  buttonsPanel.add(equal);
  buttonsPanel.setLayout(new GridLayout(4, 4));
  f.add(buttonsPanel, BorderLayout.SOUTH);
  
  //注册各个组件监听事件
  backspace.addMouseListener(new OperationMouseListener());
  CE.addMouseListener(new OperationMouseListener());
  C.addMouseListener(new OperationMouseListener());
  decimal.addMouseListener(new OperationMouseListener());
  equal.addMouseListener(new OperationMouseListener());
  
  //注册四则运算监听
  add.addMouseListener(new CalcMouseListener());
  sub.addMouseListener(new CalcMouseListener());
  mul.addMouseListener(new CalcMouseListener());
  div.addMouseListener(new CalcMouseListener());
  
  //注册数字监听事件
  zero.addMouseListener(new NumberMouseListener());
  one.addMouseListener(new NumberMouseListener());
  two.addMouseListener(new NumberMouseListener());
  three.addMouseListener(new NumberMouseListener());
  four.addMouseListener(new NumberMouseListener());
  five.addMouseListener(new NumberMouseListener());
  six.addMouseListener(new NumberMouseListener());
  seven.addMouseListener(new NumberMouseListener());
  eight.addMouseListener(new NumberMouseListener());
  nine.addMouseListener(new NumberMouseListener());
  
  f.setVisible(true);
  f.pack();
  f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 }
 
 private class NumberMouseListener implements MouseListener{

  public void mouseClicked(MouseEvent e) {
   if(input.getText().trim().equals("0")){//如果文本框已经是0，结果还是0
    input.setText(((JButton)e.getSource()).getText().trim());
   }else{//否则的话，把0添加到后面，譬如文本框是1，结果就为10
    input.setText(input.getText().concat(((JButton)e.getSource()).getText().trim()));
   }
  }

  public void mouseEntered(MouseEvent e) {}
  public void mouseExited(MouseEvent e) {}
  public void mousePressed(MouseEvent e) {}
  public void mouseReleased(MouseEvent e) {} 
 }
 
 private class CalcMouseListener implements MouseListener{
  //如果输入的是运算符号，保存第一个结果和运算符号
  public void mouseClicked(MouseEvent e) {
   num1 = input.getText().trim();input.setText("");
   operator = ((JButton)e.getSource()).getText().trim();
  }

  public void mouseEntered(MouseEvent e) {}
  public void mouseExited(MouseEvent e) {}
  public void mousePressed(MouseEvent e) {}
  public void mouseReleased(MouseEvent e) {} 
 }
 
 private class OperationMouseListener implements MouseListener{

  public void mouseClicked(MouseEvent e) {
   if(e.getSource() == backspace){//退格键，删除一个直到没有字符删除
    String inputText = input.getText();
    if(inputText.length() > 0){
     input.setText(inputText.substring(0, inputText.length() - 1));
    }
   }else if(e.getSource() == C){
    input.setText("0");//C，清空所有运算数字和符号
    num1 = "";
   }else if(e.getSource() == CE){
    input.setText("0");//CE-->将文本框置为0
   }else if(e.getSource() == decimal){
    String text = input.getText().trim();
    //如果按了小数点，如果文本框已经有小数点，不做任何操作，否则在结果后面加上小数点
    if(text.indexOf(".") == -1){
     input.setText(text.concat("."));
    }
   }else if(e.getSource() == equal){
    //如果是等号
    if(!operator.trim().equals("")){
     if(!input.getText().trim().equals("")){
      double result = 0D;
      if(operator.equals("+")){//执行加法运算
       result = Double.parseDouble(num1) + Double.parseDouble(input.getText().trim());
      }else if(operator.equals("-")){//减法运算
       result = Double.parseDouble(num1) - Double.parseDouble(input.getText().trim());
      }else if(operator.equals("*")){//乘法运算
       result = Double.parseDouble(num1) * Double.parseDouble(input.getText().trim());
      }else if(operator.equals("/")){//除法运算
       result = Double.parseDouble(num1) / Double.parseDouble(input.getText().trim());
      }
       
       //格式化最终结果，保留两位小数点
      input.setText(new DecimalFormat("0.00").format(result));
     }
    }
    
   }
   
  }

  public void mouseEntered(MouseEvent e) {}
  public void mouseExited(MouseEvent e) {}
  public void mousePressed(MouseEvent e) {}
  public void mouseReleased(MouseEvent e) {} 
 }
 
}

//通过网页实现计算器

执行算法的页面

 <form action="web/result.jsp" method="post">  
    <input type="text" name="num1"/>
    <select name="op">
    <option value="add">+</option>
    <option value="min">-</option>
    <option value="mul">*</option>
    <option value="div">/</option> 
    </select>
    <input type="text" name="num2"/>
    <br>
    <hr>
    <input type="submit" value="等于">
    <input type="reset" value="重置">
    </form>

 

//得到执行结果的页面

<c:if test="${param.op=='add'}">
   ${param.num1}+${param.num2}=${param.num1+param.num2} 
   </c:if>
   
   <c:if test="${param.op=='min'}">
   ${param.num1}-${param.num2}=${param.num1-param.num2} 
   </c:if>
   
   <c:if test="${param.op=='mul'}">
   ${param.num1}*${param.num2}=${param.num1*param.num2} 
   </c:if>
   
   <c:if test="${param.op=='div'}">
   
<%--   <%  --%>
<%--    if(${param.num2}==0)--%>
<%--    {--%>
<%--     out.println("被除数不能为0");--%>
<%--    }--%>
<%--   --%>
<%--   %>--%>
   
   ${param.num1}/${param.num2}=${param.num1/param.num2} 
   </c:if>