Web calculator based on servlet + JSP

• Java

Web calculator based on servlet + JSP

This time, the boss assigned us a task to review the jump of web pages

A big copy of the world's code depends on how you copy it

First of all, the calculation algorithm I think of is not a stack, but a simple one (it's actually very complex, but I just need to know that there is this thing, and others have done it well... The legendary CV method is good? Emmm, when you know that there is such an algorithm, but you can't write it yourself, but you can use it yourself, it's equivalent to... You can do it yourself...)

No more nonsense. It is a regular tool class collected, which supports bracket operation

package pers.cal.util;


import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
 
public class UtilArithmetic {
//    public static void main(String[] args) {
//        String src = "(3 + (5 - 2) * 10 / 2 * 3 + 15) * (8 - 4)";
//        Sy@R_404_2354@.out.println(cal(src));
//    }
    public static String cal(String src) {
        StringBuilder builder = new StringBuilder();
        if (src.contains("(")) {
            Pattern pattern = Pattern.compile("\\(([^()]+)\\)");
            Matcher matcher = pattern.matcher(src);
            int lastEnd = 0;
            while (matcher.find()) {
				
                builder.append(src.substring(lastEnd,matcher.start()));
				Sy@R_404_2354@.out.println(builder.toString());
                builder.append(cal(matcher.group(1)));
                lastEnd = matcher.end();
            }
            builder.append(src.substring(lastEnd));
        } else {
            Pattern pattern = Pattern.compile("([\\d.]+)\\s*([*/])\\s*([\\d.]+)");
            builder.append(src);
            Matcher matcher = pattern.matcher(builder.toString());
            while (matcher.find()){
                float f1 = Float.parseFloat(matcher.group(1));
                float f2 = Float.parseFloat(matcher.group(3));
                float result = 0;
                switch (matcher.group(2)){
                    case "*":
                        result = f1 * f2;
                        break;
                    case "/":
                        result = f1 / f2;
                        break;
                }
                builder.replace(matcher.start(),matcher.end(),String.valueOf(result));
                matcher.reset(builder.toString());
            }
            pattern = Pattern.compile("([\\d.]+)\\s*([+-])\\s*([\\d.]+)");
            matcher = pattern.matcher(builder.toString());
            while (matcher.find()){
                float f1 = Float.parseFloat(matcher.group(1));
                float f2 = Float.parseFloat(matcher.group(3));
                float result = 0;
                switch (matcher.group(2)){
                    case "+":
                        result = f1 + f2;
                        break;
                    case "-":
                        result = f1 - f2;
                        break;
                }
                builder.replace(matcher.start(),String.valueOf(result));
                matcher.reset(builder.toString());
            }
            return builder.toString();
        }
        Sy@R_404_2354@.out.println(builder);
        return cal(builder.toString());
    }
}

When calling, just use cal (string STR) directly

Then the corresponding foreground JSP

<%@ page language="java" contentType="text/html; charset=utf-8"
	pageEncoding="utf-8"%>
	<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!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>基于Servlet+jsp的Web计算器的项目</title>

<link href="./css/index.css" rel="stylesheet" type="text/css" />

<script type="text/javascript">
	var cleartext = false;//设置标识值
	function getNum(num) {
		//alert(num);
		var result = document.getElementById("result");
		if (cleartext) {
			result.value = "";
			//cleartext = false;
		}
		result.value += num;
	}

	function getResult() {
		var result = document.getElementById("result");
		//result.value=result.value+"="+eval(result.value);
		//next is the str we need
		result.value = result.value;
		//this result.value is the str we need
		//alert(result.value);
		//cleartext = true;//计算结果后改变标识
	}
</script>
</head>
<body>
	<div class="calculator">
		<span class="copyRight">金 聖 聰 ®</span>

		<form action="calculator.do" method="post" name="From"
			onclick="return getResult">

			<div class="calculator-display">
				<input type="text" name="result" id="result" size="33"
					readonly=readonly value="${ count}" >
			</div>

			<div class="calculator-keys">
				<button type="button" class="all-clear" value="all-clear"
					onclick="document.getElementById('result').value=''">AC</button>

				<button type="button" value="9" onclick="getNum('(')">(</button>
				<button type="button" value="9" onclick="getNum(')')">)</button>
				<button type="button" class="operator" value="+"
					onclick="getNum('+')">+</button>

				<button type="button" value="7" onclick="getNum(7)">7</button>
				<button type="button" value="8" onclick="getNum(8)">8</button>
				<button type="button" value="9" onclick="getNum(9)">9</button>

				<button type="button" class="operator" value="-"
					onclick="getNum('-')">-</button>
				<button type="button" value="4" onclick="getNum(4)">4</button>
				<button type="button" value="5" onclick="getNum(5)">5</button>
				<button type="button" value="6" onclick="getNum(6)">6</button>
				<button type="button" class="operator" value="*"
					onclick="getNum('*')">&times;</button>

				<button type="button" value="1" onclick="getNum(1)">1</button>
				<button type="button" value="2" onclick="getNum(2)">2</button>
				<button type="button" value="3" onclick="getNum(3)">3</button>

				<button type="button" class="operator" value="/"
					onclick="getNum('/')">&divide;</button>
				<button type="button" value="0" onclick="getNum(0)">0</button>
				<button type="button" class="decimal" value="."
					onclick="getNum('.')">.</button>
				<button class="equal-sign" value="=" onclick="getResult('.')">=</button>
			</div>

		</form>
	</div>


</body>
</html>

His CSS

html {
    font-size: 62.5%;
    @R_87_2419@-sizing: border-@R_87_2419@;
    margin: 0;
    padding: 0;
    @R_87_2419@-sizing: inherit
}

body {
  width: 100vw;
  min-height: 100vh;
  background-color: #B0C4DE;
  display: flex;
  justify-content: center;
  align-items: center;
}

.calculator {
  background: #1d1e22;
  padding:2.8rem .64rem .64rem;
  color: white;
  border-radius: .5rem;
  @R_87_2419@-shadow: 0 .3rem 3rem .1rem rgba(0,0.6);
  position: relative;
  min-width: 40rem;
}

.calculator-display {
  font-size: 5rem;
  height: 80px;
  padding: 0 20px;
  background-color: #1d1e22;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  
}
 #result{
	color:white; 
	background-color:#003300;
	width:100%;
	height:50%;
	font-size:33%;
	text-align:right;
}
button {
  height: 60px;
  border-radius: 3px;
  border: 1px solid #c4c4c4;
  font-size: 2rem;  
  background-color: #fff;

}

.calculator-keys {
  display: grid;
  grid-gap: 2rem;
  padding: 2rem 1.36rem;
  background-color: #fff;
}

.equal-sign {
  grid-row: 5 / span 1;
  grid-column: 3 / 5;
  height: 100%;
}
.copyRight{
	text-align: center;
	display:block;
	color:black;
	font-weight:bolder;
	font-size: 33px;
}

Look like this

The El expression is used

Related jar packages

XML configuration

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://java.sun.com/xml/ns/javaee"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	id="WebApp_ID" version="2.5">
	<display-name>Calculation</display-name>

	<servlet>
		<servlet-name>ServletDemo</servlet-name>
		<servlet-class>pers.cal.servlet.CalculationServlet</servlet-class>
	</servlet>

	<servlet-mapping>
		<servlet-name>ServletDemo</servlet-name>
		<url-pattern>/calculator.do</url-pattern>
	</servlet-mapping>
</web-app>

Corresponding Servlet

package pers.cal.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import pers.cal.util.UtilArithmetic;

public class CalculationServlet extends HttpServlet {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;


	@Override
	protected void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException {
		doPost(req,resp);
	}
	
	
	@Override
	protected void doPost(HttpServletRequest req,IOException {
	
		String result = req.getParameter("result");
	//	req.setAttribute("result","admin");
		String finalRes = result;
		result = finalRes+"="+UtilArithmetic.cal(result);
		
		HttpSession session = req.getSession();
		session.setAttribute("count",result);
		Sy@R_404_2354@.out.println(result);
		req.getRequestDispatcher("index.jsp").forward(req,resp);
	}

	
}

Finally, the structure

good night.

Have a good dream

おやすみ～

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