javaweb做一个计算器

ゞ浴缸里的玫瑰 2022-08-12 08:29 215阅读 0赞

首先需要有一个封装计算数和计算的类

package cn.itcast.domain;
    
    import java.math.BigDecimal;
    
    
    // 封装计算的bean
    public class CalculatorBean {
    	private String firstNum="0";
    	private char operator='+';
    	private String secondNum="0";
    	private String result;
    	public String getFirstNum() {
    		return firstNum;
    	}
    	public void setFirstNum(String firstNum) {
    		this.firstNum = firstNum;
    	}
    	public char getOperator() {
    		return operator;
    	}
    	public void setOperator(char 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 void calculate(){
    		BigDecimal first = new BigDecimal(this.firstNum);
    		BigDecimal second = new BigDecimal(this.secondNum);
    		
    		switch (this.operator) {
    			case '+':
    				this.result = first.add(second).toString();
    				break;
    			case '-':
    				this.result = first.subtract(second).toString();
    				break;
    			case '*':
    				this.result = first.multiply(second).toString();
    				break;
    			case '/':
    				if(second.doubleValue()==0){
    					throw new RuntimeException("被除数不能为0");
    				}
    				this.result = first.divide(second,20,BigDecimal.ROUND_HALF_UP).toString();
    				break;
    			default:
    				throw new RuntimeException("运算符不正确");
    
    				
    		}
    	}
    }

然后再jsp页面计算和输出

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body style="text-align:center;">
    
    	<jsp:useBean id="CalculatorBean" class="cn.itcast.domain.CalculatorBean"></jsp:useBean>
    	
    	<jsp:setProperty property="*" name="CalculatorBean"/>
    	
    	<%
    		try{
    			CalculatorBean.calculate();
    		}catch(Exception e){
    			out.write(e.getMessage());
    		}
    	%>
    	
    	<hr>
    	计算结果是：
    	<jsp:getProperty property="firstNum" name="CalculatorBean"/>
    	<jsp:getProperty property="operator" name="CalculatorBean"/>
    	<jsp:getProperty property="secondNum" name="CalculatorBean"/>
    	=
    	<jsp:getProperty property="result" name="CalculatorBean"/>
    	<hr>
    	
    	<form action="/day08/calculator.jsp" method="post">
    	<table width="40%" border="1" align="center">
    		<tr>
    			<td colspan="2">简单的计算器</td>
    		</tr>
    		<tr>
    			<td>第一个数</td>
    			<td>
    				<input type="text" name="firstNum">
    			</td>
    		</tr>
    		<tr>
    			<td>操作符</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>

结果是

![SouthEast][]

可用于计算

[SouthEast]: /images/20220810/6c5784df8b8944b1bc20d2f0de1a57f9.png