（1）jsp实现网页计算器代码如下：只有两个jsp页面
myCal.jsp如下：
<%@ 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 'myCal.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!-- jsp页面中不可以直接使用script -->
<script language="javascript">
<!--
//写一个函数判断是否两个数都有
function checkNum()
{
//判断num1 num2是否为空
if((form1.num1.value == "") || (form1.num2.value == ""))
{
window.alert("null,不能为空！");
return false;
}
//判断是否是数字
if(Math.round(form1.num1.value) != form1.num1.value && Math.round(form1.num2.value) != form1.num2.value)
{
window.alert("num1和num2不是一个数");
return false;
}
if(Math.round(form1.num1.value) != form1.num1.value)
{
window.alert("num1不是一个数");
return false;
}
if(Math.round(form1.num2.value) != form1.num2.value)
{
window.alert("num2不是一个数");
return false;
}
}
-->
</script>
</head>
<body>
<form name="form1" action="calculator/myResult.jsp" method="post">
请输入第一个数：<input type="text" name="num1">
<select name="flag">
<option value=+>+</option>
<option value=->-</option>
<option value=*>*</option>
<option value=/>/</option>
</select>
请输入第二个数：<input type="text" name="num2">
<input type="submit" value="计算" onclick="return checkNum();">
</form>
</body>
</html>
<%@ 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 'myResult.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<%
//第1步接收到 第1个数
String s_num1 = request.getParameter("num1");
//第2步接收到 第2个数
String s_num2 = request.getParameter("num2");
//第3步接收到 运算符
String flag = request.getParameter("flag");
//第4步 计算
int num1 = Integer.parseInt(s_num1);
int num2 = Integer.parseInt(s_num2);
int result = 0;
if(flag.equals("+"))
{
result = num1+num2;
}
else if(flag.equals("-"))
{
result = num1-num2;
}
else if(flag.equals("*"))
{
result = num1*num2;
}
else if(flag.equals("/"))
{
result = num1/num2;
}
//第5步
out.println("结果是:"+result);
%>
</body>
</html>
（2）虽然过程很简单但是有几个值得学习的地方：
如何判断输入的数据是不是数字：使用Math.round(form1.num1.value) != form1.num1.value 来判断；
如何获取操作值：设置name属性 flag实现；
原文地址：http://blog.csdn.net/xlgen157387/article/details/39136985
