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javaweb之jsp+javabean开发模式的web计算器

2014-03-16 23:57 429 查看

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>

<title>计算器</title>
<style type="text/css">
body{
margin:0px;
padding:0px;
text-align: center
}
form{
margin-left:500px;
}
</style>
</head>

<body>

<jsp:useBean id="calculatorBean" class="test.domain.CalculatorBean"/>
<jsp:setProperty name="calculatorBean" property="*" />

<%
try {
calculatorBean.calculate();
}catch(Exception e) {
out.write(e.getMessage());
}
%>

<br/>-----------------------------------------------------<br/>
计算结果是：
<jsp:getProperty name="calculatorBean" property="firstNum" />
<jsp:getProperty name="calculatorBean" property="operator" />
<jsp:getProperty name="calculatorBean" property="secondNum" />
=
<jsp:getProperty name="calculatorBean" property="result" />
<br/>-----------------------------------------------------<br/>

<br/>

<form action="/day09/calculator.jsp" method="post">
<table width="40%" 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"/></td>
</tr>

<tr>
<td>运算符</td>
<td>
<select name="operator">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select>
</td>
</tr>

<tr>
<td>第二个参数</td>
<td><input type="text" name="secondNum"/></td>
</tr>

<tr>
<td colspan="2"><input type="submit" value="计算"/></td>
</tr>
</table>
</form>
</body>
</html>

package test.domain;

import java.math.BigDecimal;

//封装计算器数据的bean
public class CalculatorBean {
private String firstNum = "0";
private char operator = '+';
private String secondNum = "0";
private String result;
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;
}

public void calculate() {
BigDecimal first = new BigDecimal(this.firstNum);
BigDecimal second = new BigDecimal(this.secondNum);
switch(this.operator) {
case '+':{
this.result = first.add(second).toString();
break;
}
case '-':{
this.result = first.subtract(second).toString();
break;
}
case '*':{
this.result = first.multiply(second).toString();
break;
}
case '/':{
if(second.doubleValue() == 0) {
throw new RuntimeException("被除数为0");
}
this.result = first.divide(second, 20, BigDecimal.ROUND_HALF_UP).toString();
break;
}
default:
throw new RuntimeException("运算符只能是+-*/");
}
}

}

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