jsp部分的代码：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'caculate.jsp' starting page</title>
</head>
<body style="text-align: center;">
<%--把请求数据封装到bean里面 --%>
<jsp:useBean id="caculateBean" class="com.caculator.caculateBean" />
<%--参数名相同，用*代替 --%>
<jsp:setProperty name="caculateBean" property="*" />
<%--这里要捕获抛出的异常并输出--%>
<%
try {
caculateBean.caculate();
} catch (Exception e) {
out.write(e.getMessage());
}
%>
<br />-----------------------------------------------------------
<br /> 计算结果为：
<jsp:getProperty name="caculateBean" property="firstNum" />
<jsp:getProperty name="caculateBean" property="operator" />
<jsp:getProperty name="caculateBean" property="secondNum" />
=
<jsp:getProperty name="caculateBean" property="result" />
<br />-----------------------------------------------------------
<br />
<form action="/day0830/caculate.jsp" method="post">
<table border="1" width="30%" align="center">
<tr>
<td colspan="2" align="center"><strong>简单的计算器</strong>
</td>
</tr>
<tr>
<td>第一个数：</td>
<td><input type="text" name="firstNum" id="firstNum">
</td>
</tr>
<tr>
<td>选择运算符</td>
<td><select name="operator">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select></td>
</tr>
<tr>
<td>第二个数</td>
<td><input type="text" name="secondNum" id="secondNum">
</td>
</tr>
<tr>
<td colspan="2"><input type="submit" value=" 计算 ">
</td>
</tr>
</table>
</form>
</body>
</html>
javaBean部分的代码
package com.caculator;
import java.math.BigDecimal;
//封装计算器数据的bean
public class caculateBean {
private String firstNum="0";
private String secondNum="1";
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 caculate(){
BigDecimal first=new BigDecimal(this.firstNum);
BigDecimal second=new BigDecimal(this.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("除数不能为0");
}
this.result=first.divide(second).toString();
break;
}
default:
throw new RuntimeException("运算符错误！");
}
}
}