[Java.web]简单计算器
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[Java.web]简单计算器
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項目的 WebRoot 目錄下的calculator.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML>
<html>
<head>
<title>計算結果</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("計算出錯：<font color='red'>" + ex.getMessage()
+ "</font>");
}
%>
<hr />
<label>計算的結果是：<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">簡單計算器</td>
</tr>
<tr>
<td>第一個參數</td>
<td><input type="text" name="arg1" />
</td>
</tr>
<tr>
<td>運算符</td>
<td><select name="operator">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select>
</td>
</tr>
<tr>
<td>第二個參數</td>
<td><input type="text" name="arg2" />
</td>
</tr>
<tr>
<td colspan="2" align="center"><input type="submit" value="計算" />
</td>
</tr>
</table>
</form>
</body>
</html>
項目的 src 目錄下的 包下面的CalculatorBean.java
package cn.itcast.domain;
import java.math.BigDecimal;
// 封裝計算方法 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 = "除零錯誤！";
//break;
throw new RuntimeException("除零錯誤！");
}
result = firstBigDecimal.divide(sencondBigDecimal, 20,
BigDecimal.ROUND_HALF_UP).toString();
break;
default:
result = "未設定的操作！" + String.valueOf(this.operator);
break;
}
}
}
附上效果圖：
總結
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