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jsp开发模式和web计算器案例
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>
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 }
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