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JSP页面实现简单的计算器(JSP+JavaBean适合简单页面显示)

2013-06-09 11:26 525 查看

1,CalculatorBean.java的实现封装数据和操作符.

import java.math.BigDecimal;

public class CalculatorBean {

private double firstNum;
private double secondNum;
private char operator = '+'; // int char byte short
private double result;

public double getFirstNum() {
return firstNum;
}

public void setFirstNum(double firstNum) {
this.firstNum = firstNum;
}

public double getSecondNum() {
return secondNum;
}

public void setSecondNum(double secondNum) {
this.secondNum = secondNum;
}

public char getOperator() {
return operator;
}

public void setOperator(char operator) {
this.operator = operator;
}

public double getResult() {
return result;
}

public void setResult(double result) {
this.result = result;
}

public void calculate() {

switch (this.operator) {
case '+': {
this.result = this.firstNum + this.secondNum;
break;
}

case '-': {
this.result = this.firstNum - this.secondNum;
break;
}
case '*': {
this.result = this.firstNum * this.secondNum;
break;
}
case '/': {
if (this.secondNum == 0) {
throw new RuntimeException("被除数不能为0!!!");
}

this.result = this.firstNum / this.secondNum;

// 四舍五入
this.result = new BigDecimal(this.result).setScale(2,
BigDecimal.ROUND_HALF_UP).doubleValue();

break;
}

default:
throw new RuntimeException("对不起，传入的运算符非法！！");
}

}

}

2,JSP显示层

<%@ 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>
</head>

<body style="text-align: center;">

<jsp:useBean id="CalculatorBean" class="cn.itcast.CalculatorBean"></jsp:useBean>
<jsp:setProperty name="CalculatorBean" property="*" />
<%
CalculatorBean.calculate();
%>

<br />
<hr>
<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 />
<hr>
<br />

<form action="/day09/calculator.jsp" method="post">
<table border="1" width="50%">
<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>

效果图

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