<%@ 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;
} }
04-19 18:05
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