jsp开发模式和web计算器案例

浏览数：16 / 时间：2015年06月09日

 1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
 2 <%
 3 String path = request.getContextPath();
 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 5 %>
 6 
 7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 8 <html>
 9   <head>
10     <base href="<%=basePath%>">
11     
12     <title>My JSP ‘Calculator.jsp‘ starting page</title>
13     
14 
15   </head>
16   
17   <body>
18   
19       <jsp:useBean id="Calculator" class="cn.itcast.domain.Calculator"></jsp:useBean>
20       <jsp:setProperty property="*" name="Calculator"/>
21       
22       <%
23           try{
24           Calculator.calculate();
25           }catch(Exception e){
26               out.write(e.getMessage());
27           }
28        %>
29        
30        <br/>--------------------------------------------<br/>
31            计算的结果是：
32            <jsp:getProperty name="Calculator" property="firstnum"/>
33            <jsp:getProperty name="Calculator" property="operator"/>
34            <jsp:getProperty name="Calculator" property="secondnum"/>
35            =
36            <jsp:getProperty name="Calculator" property="result"/>
37        <br/>--------------------------------------------<br/>
38       <br/>
39       <form action="/JSPDemo/Calculator.jsp" method="post" style="text-align:center;">
40           <table width="40%" border="1">
41             <tr>
42                 <td colspan="2">简单的计算器</td>
43             </tr>
44             <tr>
45                 <td>第一个参数</td>
46                 <td>
47                     <input type="text" name="firstnum" />    
48                 </td>
49             </tr>
50             <tr>
51                 <td>操作符</td>
52                 <td>
53                     <select name="operator" >
54                         <option value="+">+</option>
55                         <option value="-">-</option>
56                         <option value="*">*</option>
57                         <option value="/">/</option>
58                     </select>
59                 </td>
60             </tr>
61             <tr>
62                 <td>第二个参数</td>
63                 <td>
64                     <input type="text" name="secondnum" />    
65                 </td>
66             </tr>
67             <tr>
68                 <td colspan="2">
69                     <input type="submit" value="计算" />
70                 </td>
71             </tr>
72         </table>
73       </form>
74         
75   </body>
76 </html>

Calculator.jsp

 1 package cn.itcast.domain;
 2 
 3 
 4 import java.math.BigDecimal;
 5 
 6 //封装计算器数据的bean
 7 public class Calculator {
 8 
 9     private String firstnum = "0";
10     private String secondnum = "0";
11     private char operator = ‘+‘;
12     private String result;
13     
14     public void calculate(){
15         BigDecimal first = new BigDecimal(this.firstnum);
16         BigDecimal second = new BigDecimal(this.secondnum);
17         
18         switch(this.operator){
19         case ‘+‘:{
20                 this.result = first.add(second).toString();
21                 break;
22             }
23         case ‘-‘:{
24             this.result = first.subtract(second).toString();
25             break;
26         }
27         case ‘*‘:{
28             this.result = first.multiply(second).toString();
29             break;
30         }
31         case ‘/‘:{
32             if(second.doubleValue()==0){
33                 throw new RuntimeException("被除数不能为0");
34             }
35             this.result = first.divide(second,20,BigDecimal.ROUND_HALF_UP).toString();
36             break;
37         }
38         
39         default:
40             throw new RuntimeException("运算符只能+-*/");
41         }
42         
43     }
44 
45     public String getFirstnum() {
46         return firstnum;
47     }
48 
49     public void setFirstnum(String firstnum) {
50         this.firstnum = firstnum;
51     }
52 
53     public String getSecondnum() {
54         return secondnum;
55     }
56 
57     public void setSecondnum(String secondnum) {
58         this.secondnum = secondnum;
59     }
60 
61     public char getOperator() {
62         return operator;
63     }
64 
65     public void setOperator(char operator) {
66         this.operator = operator;
67     }
68 
69     public String getResult() {
70         return result;
71     }
72 
73     public void setResult(String result) {
74         this.result = result;
75     }
76 }