JavaBean创建和使用——计算器
1、掌握JavaBean创建和使用方法；
2、领会JavaBean简化页面设计的优势等。
设计简单计算器
要求：完成加减乘除
? ? 当除数为零时报错
? ? 将加减乘除部分写在JavaBean中，在JSP页面中调用显示计算结果。
Calculator.java
?
package com.jk.yt;
import java.math.BigDecimal;
public class Calculator {
private String onenum = "0";
private String twonum = "0";
private char fuhao = ‘+‘;
private String result;
public String getOnenum() {
return onenum;
}
public void setOnenum(String onenum) {
this.onenum = onenum;
}
public String getTwonum() {
return twonum;
}
public void setTwonum(String twonum) {
this.twonum = twonum;
}
public char getFuhao() {
return fuhao;
}
public void setFuhao(char fuhao) {
this.fuhao = fuhao;
}
public String getResult() {
return result;
}
public void setResult(String result) {
this.result = result;
}
public void calculate(){
BigDecimal a=new BigDecimal(this.onenum);
BigDecimal b=new BigDecimal(this.twonum);
switch (this.fuhao) {
case ‘+‘:
this.result=a.add(b).toString();
break;
case ‘-‘:
this.result=a.subtract(b).toString();
break;
case ‘*‘:
this.result=a.multiply(b).toString();
break;
case ‘/‘:
if(b.doubleValue()==0){
throw new RuntimeException("<h1>sorry，出错了！！除数不能为零</h1>");
}
this.result=a.divide(b,10,BigDecimal.ROUND_HALF_DOWN).toString();
break;
default:
break;
}
}
}
?index.jsp：
?
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>计算器</title>
<style type="text/css">
#top {
text-align: center;
}
table {
width:330px;
height:220px;
text-align: center;
margin: 0 auto;
background: url(4.jpg);
}
</style>
</head>
<body>
<jsp:useBean id="calculate" class="com.jk.yt.Calculator"></jsp:useBean>
<jsp:setProperty property="*" name="calculate" />
<%
try {
calculate.calculate();
%>
<div id="top">
<h1>
计算结果：
<jsp:getProperty property="onenum" name="calculate" />
<jsp:getProperty property="fuhao" name="calculate" />
<jsp:getProperty property="twonum" name="calculate" />
=<jsp:getProperty property="result" name="calculate" />
</h1>
<hr>
</div>
<form action="index.jsp" method="post" name="form">
<table>
<tr>
<td colspan="2"><h1>简单的计算器</h1></td>
</tr>
<tr>
<td>第一个参数</td>
<td><input type="text" name="onenum" /></td>
</tr>
<tr>
<td colspan="2"><select name="fuhao" id="jisuan">
<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="twonum" /></td>
</tr>
<tr>
<td colspan="2">
<button type="submit">计算</button>
</td>
</tr>
</table>
</form>
<%
} catch (Exception e) {
out.write(e.getMessage());
}
%>
</body>
</html>
?最终结果如图所示：
加法：
?乘法：
?除法，除数为零时报错
代码上传至附件：Jspwork501.zip
?
?
?
原文：http://leaf-stop.iteye.com/blog/2302381