web計算器案例

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

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

</head>

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

<jsp:useBean id="calcuilatorBean" class="cn.itcast.domain.CalcuilatorBean"></jsp:useBean>
<jsp:setProperty property="*" name="calcuilatorBean"/>

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

<br/>-----------------------------------------------------------<br/>
計算結果是：
<jsp:getProperty property="firstNum" name="calcuilatorBean"/>
<jsp:getProperty property="operator" name="calcuilatorBean"/>
<jsp:getProperty property="secondNum" name="calcuilatorBean"/>
=
<jsp:getProperty property="result" name="calcuilatorBean"/>

<br/>-----------------------------------------------------------

<br/>

<form action="/day09/calculate.jsp" method="post">
<table>

<tr width="40" border="1">
<td colspan="2">簡單的計算器</td>
</tr>

<tr>
<td>第一個引數</td>
<td>
<input type="text" name="firstNum">
</td>
</tr>

<tr>
<td>操作符</td>
<td>
<select name="operator">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/"></option>

</select>
</td>
</tr>

<tr>
<td>第二個引數</td>
<td>
<input type="text" name="secondNum">
</td>
</tr>

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

</html>

package cn.itcast.domain;

import java.math.BigDecimal;

//封裝計算機資料的bean
public class CalcuilatorBean {

private String firstNum = "0";
private String secondNum = "0";
private char operator = '+';
private String result;
public String getFirstNum() {
return firstNum;
}
public void setFirstNum(String firstNum) {
this.firstNum = firstNum;
}
public String getSecondNum() {
return secondNum;
}
public void setSecondNum(String secondNum) {
this.secondNum = secondNum;
}

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 first = new BigDecimal(firstNum);
BigDecimal second = new BigDecimal(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("被除數不能為0");
}
this.result = first.divide(second,20,BigDecimal.ROUND_HALF_UP).toString();
break;
}
default:
throw new RuntimeException("只能為+-*、/");

}
}
}

web計算器案例

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