JavaWeb学习记录（二十）——Model1模式（javaBean+jsp）实现简单计算器案例

¨JSP技术提供了三个关于JavaBean组件的动作元素，即JSP标签，它们分别为：

¨<jsp:useBean>标签：用于在JSP页面中查找或实例化一个JavaBean组件。

¨<jsp:setProperty>标签：用于在JSP页面中设置一个JavaBean组件的属性。

<jsp:getProperty>标签：用于在JSP页面中获取一个JavaBean组件的属性

一、计算器的实体Bean

package web13.domain;

public class Calculator {
   private double firstNum;
   private double secondNum;
   private String oper;
   private double result;
   public Calculator() {
       super();
       // TODO Auto-generated constructor stub
   }
   public Calculator(double firstNum, double secondNum, String oper,
           double result) {
       super();
       this.firstNum = firstNum;
       this.secondNum = secondNum;
       this.oper = oper;
       this.result = result;
   }
   public double getFirstNum() {
       return firstNum;
   }
   public void setFirstNum(double firstNum) {
       this.firstNum = firstNum;
   }
   public double getSecondNum() {
       return secondNum;
   }
   public void setSecondNum(double secondNum) {
       this.secondNum = secondNum;
   }
   public String getOper() {
       return oper;
   }
   public void setOper(String oper) {
       this.oper = oper;
   }
   public void calculator(){
       if("+".equals(oper)){
           result=firstNum+secondNum;
       }else if("-".equals(oper)){
           result=firstNum-secondNum;
       }else if("*".equals(oper)){
           result=firstNum*secondNum;
       }else if("/".equals(oper)){
           result=firstNum/secondNum;
       }
   }
   public double getResult() {
       calculator();
       return result;
   }
   public void setResult(double result) {
       this.result = result;
   }

}

二、jsp页面（cal.jsp）

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%
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 'cal.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">
   

</head>

<body>
    <div>
       <jsp:useBean /></td>
           </tr>
       </table>
       </form>
    </div>
</body>
</html>