项目的 WebRoot 目录下的 calculator.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML> <html> <head> <title>计算结果</title> </head> <body> <jsp:useBean id="calculatorBean" class="cn.itcast.domain.CalculatorBean"></jsp:useBean> <jsp:setProperty property="*" name="calculatorBean" /> <% try { calculatorBean.calculate(); } catch (Exception ex) { out.write("计算出错：<font color='red'>" + ex.getMessage() + "</font>"); } %> <hr /> <label>计算的结果是：<span id="x1"> <jsp:getProperty property="arg1" name="calculatorBean" /> </span> <span id="x2"><jsp:getProperty property="operator" name="calculatorBean" /></span> <span id="x3"> <jsp:getProperty property="arg2" name="calculatorBean" /> </span> = <span id="x4"> <jsp:getProperty property="result" name="calculatorBean" /> </span> </label> <hr /> <form method="post" action="#"> <table border="1"> <tr> <td colspan="2">简单计算器</td> </tr> <tr> <td>第一个参数</td> <td><input type="text" name="arg1" /> </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="arg2" /> </td> </tr> <tr> <td colspan="2" align="center"><input type="submit" value="计算" /> </td> </tr> </table> </form> </body> </html>
项目的 src 目录下的 包下面的 CalculatorBean.java
package cn.itcast.domain; import java.math.BigDecimal; // 封装计算方法 Bean public class CalculatorBean { private String arg1 = "0"; private String arg2 = "0"; private char operator = '+'; private String result; public String getArg1() { return arg1; } public void setArg1(String arg1) { this.arg1 = arg1; } public String getArg2() { return arg2; } public void setArg2(String arg2) { this.arg2 = arg2; } public char getOperator() { return operator; } public void setOperator(char operator) { this.operator = operator; } public String getResult() { return result; } public void setResult(String result) { this.result = result; } public void calculate() { BigDecimal firstBigDecimal = new BigDecimal(arg1); BigDecimal sencondBigDecimal = new BigDecimal(arg2); switch (this.operator) { case '+': result = firstBigDecimal.add(sencondBigDecimal).toString(); break; case '-': result = firstBigDecimal.subtract(sencondBigDecimal).toString(); break; case '*': result = firstBigDecimal.multiply(sencondBigDecimal).toString(); break; case '/': if (sencondBigDecimal.doubleValue() == 0) { //result = "除零错误！"; //break; throw new RuntimeException("除零错误！"); } result = firstBigDecimal.divide(sencondBigDecimal, 20, BigDecimal.ROUND_HALF_UP).toString(); break; default: result = "未设定的操作！" + String.valueOf(this.operator); break; } } }
附上效果图：
