<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>jsp 和 javaBean 实现计算器功能</title> </head> <body> <jsp:useBean id="calculator" class="de.bvb.domain.Calculator" /> <jsp:setProperty property="*" name="calculator" /> <% try { calculator.calculate(); } catch (Exception e) { out.write(e.getMessage()); } %> <form action="/web/calculator.jsp" method="post"> <table width="50%" border="1"> <tr> <td colspan="2">简单的计算器</td> </tr> <tr> <td>第一个参数</td> <td><input type="text" name="firstNum" value="11"></td> </tr> <tr> <td>运算符</td> <td><select name="operator"> <option value="+">+</option> <option value="-">-</option> <option value="*">*</option> <option value="/" selected="selected">/</option> </select></td> </tr> <tr> <td>第二个参数</td> <td><input type="text" name="secondNum" value="0" ></td> </tr> <tr> <td colspan="2"><input type="submit" value="计算"></td> </tr> <tr> <td>结果</td> <td> <jsp:getProperty property="firstNum" name="calculator" /> <jsp:getProperty property="operator" name="calculator" /> <jsp:getProperty property="secondNum" name="calculator" /> = <jsp:getProperty property="result" name="calculator" /> </td> </tr> </table> </form> </body> </html>
package de.bvb.domain; import java.math.BigDecimal; public class Calculator { private String firstNum = "0"; private char operator = '+'; private String secondNum = "0"; private String result; public void calculate() { BigDecimal first = new BigDecimal(firstNum); BigDecimal seconde = new BigDecimal(secondNum); switch (operator) { case '+': result = first.add(seconde).toString(); break; case '-': result = first.subtract(seconde).toString(); break; case '*': result = first.multiply(seconde).toString(); break; case '/': if (Double.parseDouble(secondNum) == 0) { throw new RuntimeException("除数不能为０"); } result = first.divide(seconde, 20, BigDecimal.ROUND_HALF_UP) .toString(); break; default: throw new RuntimeException("数据或操作符异常"); } } public String getFirstNum() { return firstNum; } public void setFirstNum(String firstNum) { this.firstNum = firstNum; } public char getOperator() { return operator; } public void setOperator(char operator) { this.operator = operator; } public String getSecondNum() { return secondNum; } public void setSecondNum(String secondNum) { this.secondNum = secondNum; } public String getResult() { return result; } public void setResult(String result) { this.result = result; } }