项目的 WebRoot 目录下的 calculator.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML>
<html>
<head>
<title>计算结果</title>
</head>
<body>
<jsp:useBean id="calculatorBean"
class="cn.itcast.domain.CalculatorBean"></jsp:useBean> <jsp:setProperty property="*" name="calculatorBean" />
<%
try {
calculatorBean.calculate();
} catch (Exception ex) {
out.write("计算出错：<font color='red'>" + ex.getMessage()
+ "</font>");
}
%> <hr />
<label>计算的结果是：<span id="x1"> <jsp:getProperty
property="arg1" name="calculatorBean" /> </span> <span id="x2"><jsp:getProperty
property="operator" name="calculatorBean" /></span> <span id="x3">
<jsp:getProperty property="arg2" name="calculatorBean" /> </span> = <span
id="x4"> <jsp:getProperty property="result"
name="calculatorBean" /> </span> </label>
<hr /> <form method="post" action="#">
<table border="1">
<tr>
<td colspan="2">简单计算器</td>
</tr>
<tr>
<td>第一个参数</td>
<td><input type="text" name="arg1" />
</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="arg2" />
</td>
</tr>
<tr>
<td colspan="2" align="center"><input type="submit" value="计算" />
</td>
</tr>
</table>
</form>
</body>
</html>
项目的 src 目录下的 包下面的 CalculatorBean.java
package cn.itcast.domain; import java.math.BigDecimal; // 封装计算方法 Bean
public class CalculatorBean {
private String arg1 = "0"; private String arg2 = "0"; private char operator = '+'; private String result; public String getArg1() {
return arg1;
} public void setArg1(String arg1) {
this.arg1 = arg1;
} public String getArg2() {
return arg2;
} public void setArg2(String arg2) {
this.arg2 = arg2;
} public char getOperator() {
return operator;
} public void setOperator(char operator) {
this.operator = operator;
} public String getResult() {
return result;
} public void setResult(String result) {
this.result = result;
} public void calculate() {
BigDecimal firstBigDecimal = new BigDecimal(arg1);
BigDecimal sencondBigDecimal = new BigDecimal(arg2); switch (this.operator) {
case '+':
result = firstBigDecimal.add(sencondBigDecimal).toString();
break;
case '-':
result = firstBigDecimal.subtract(sencondBigDecimal).toString();
break;
case '*':
result = firstBigDecimal.multiply(sencondBigDecimal).toString();
break;
case '/':
if (sencondBigDecimal.doubleValue() == 0) {
//result = "除零错误！";
//break;
throw new RuntimeException("除零错误！");
}
result = firstBigDecimal.divide(sencondBigDecimal, 20,
BigDecimal.ROUND_HALF_UP).toString();
break;
default:
result = "未设定的操作！" + String.valueOf(this.operator);
break;
}
}
}
附上效果图：