使用JSP制作一个超简单的网页计算器的实例分享

来源：测品娱乐

实现一个简单的计算器程序，要求：使用jsp+javabean模式实现。
项目源代码如下：
文件：calculator.jsp

<%@ page language="java" pageEncoding="UTF-8"%> 
<%@ page isErrorPage="true"%> 
<%@ page errorPage="calculator.jsp" %> 
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
 <head> 
 <title>简单的计算机</title> 
 </head> 
 
 <body> 
 <%--创建Calculator对象--%> 
 <jsp:useBean id="cal" class="cn.zq.domain.Calculator" /> 
 <%--设置值 通配符*表示设置所有属性--%> 
 <jsp:setProperty property="*" name="cal"/> 
 
 
 <%-- 
 进行计算 
 --%> 
 <c:if test="${empty pageContext.exception}"> 
 <% 
 cal.calculate(); 
 %> 
 </c:if> 
 
 
 <hr/> 
 <p>计算结果：${cal.firstNum } ${cal.operator } ${cal.secondNum } = ${cal.result }</p> 
 <hr/> 
 
 <%-- 
 构建url 
 --%> 
 <c:url var="formUrl" value="/calculator.jsp"/> 
 <form action="${formUrl }" method="post"> 
 <table border="1" cellpadding="2"> 
 <tr> 
 <td colspan="2" align="center">我的计算器</td> 
 </tr> 
 <tr> 
 <td>第一个参数:</td> 
 <td><input type="text" name="firstNum"/></td> 
 </tr> 
 <tr> 
 <td>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>第二个参数：</td> 
 <td> 
 <input type="text" name="secondNum"> 
 </td> 
 </tr> 
 <tr> 
 <td colspan="2"> 
 <input type="submit" value="计算" /> 
 </td> 
 </tr> 
 </table> 
 </form> 
 </body> 
</html>

本文使用的javabean代码如下：

package cn.zq.domain; 
 
public class Calculator { 
 private String firstNum; 
 private String operator; 
 private String secondNum; 
 private String result; 
 public String getFirstNum() { 
 return firstNum; 
 } 
 public void setFirstNum(String firstNum) { 
 this.firstNum = firstNum; 
 } 
 public String getOperator() { 
 return operator; 
 } 
 public void setOperator(String operator) { 
 this.operator = operator; 
 } 
 public String getSecondNum() { 
 return secondNum; 
 } 
 public void setSecondNum(String secondNum) { 
 this.secondNum = secondNum; 
 } 
 public String getResult() { 
 return result; 
 } 
 public void setResult(String result) { 
 this.result = result; 
 } 
 public Calculator() {} 
 public Calculator(String firstNum, String operator, String secondNum, 
 String result) { 
 this.firstNum = firstNum; 
 this.operator = operator; 
 this.secondNum = secondNum; 
 this.result = result; 
 } 
 
 public void calculate(){ 
 if(operator != null && !operator.equals("")){ 
 double first = new Double(firstNum); 
 double second = new Double(secondNum); 
 char oper = operator.charAt(0); 
 switch (oper) { 
 case '+': 
 result = first + second + ""; 
 break; 
 case '-': 
 result = first - second + ""; 
 break; 
 case '*': 
 result = first * second + ""; 
 break; 
 case '/': 
 result = first / second + ""; 
 break; 
 default: 
 throw new RuntimeException("未知运算符!"); 
 } 
 } 
 } 
}

最终完成的效果图如下：

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