基于Servlet+jsp的web计算器
这次老大为了让我们自己复习web中页面的跳转给不值得任务
天下代码一大抄，关键看你怎么抄
首先我想到的计算算法不是什么堆栈，是简单的（其实很复杂，但是我就只需要知道有这个东西，东西别人做好了...传说中的CV大法好？Emmm，当你知道有这么个算法但是不会自己写可是自己会用的时候，也就相当于...自己会了.....）
废话不多说一下是收集的正则工具类，支持括号运算
package pers.cal.util;import java.util.regex.Matcher;import java.util.regex.Pattern;/** * 正则表达式实现的计算器带括号版本 * @author Administrator * */public class UtilArithmetic { ???/** ????* 计算可能含有括号的表达式 ????* ?????* @param s ????* @return ????*/ ???public static String calcu(String s) { ???????s = s.replaceAll(" +", "");// 消除空格，空格可以是一个或多个，找到就替换 ???????// \\(为左括号 \\)右括号，表示在括号内没有其他括号，然后用括号括起来是一个子组e ???????Pattern pa = Pattern.compile("\\(([^\\(\\)]*)\\)"); ???????while (true) { ???????????Matcher ma = pa.matcher(s); ???????????if (ma.find() == false) ???????????????break; ???????????// 先计算括号内，然后消除括号 ???????????s = s.replace(ma.group(), calcuNoParen(ma.group(1))); ???????} ???????return calcuNoParen(s); ???} ???/** ????* 计算没有括号的运算 ????* ?????* @param s2 ????* @return ????*/ ???public static String calcuNoParen(String s2) { ???????if (s2.length() < 1) ???????????return s2; ???????// 先把乘法消除 ???????Pattern pat = Pattern.compile("([0-9]+)\\*([0-9]+)");//0-9一个或多个，乘法 ???????while (true) { ???????????Matcher mc = pat.matcher(s2); ???????????if (mc.find() == false) ???????????????break; ???????????int res = Integer.parseInt(mc.group(1)) * Integer.parseInt(mc.group(2)); ???????????// 计算出结果，并且消除括号，注意这里不能用replaceAll ???????????s2 = s2.replace(mc.group(), res + ""); ???????} ???????// 再从左到右消除所有加法和减法 ???????pat = Pattern.compile("([0-9]+)([\\+\\-])([0-9]+)");// 0-9一个或多个，加法或者减法 ???????while (true) { ???????????Matcher mc = pat.matcher(s2); ???????????if (mc.find() == false) ???????????????break; ???????????int res = 0; ???????????switch (mc.group(2)) { ???????????case "+": ???????????????res = Integer.parseInt(mc.group(1)) + Integer.parseInt(mc.group(3)); ???????????????break; ???????????case "-": ???????????????res = Integer.parseInt(mc.group(1)) - Integer.parseInt(mc.group(3)); ???????????????break; ???????????} ???????????// 计算出结果，并且消除括号，注意这里不能用replaceAl ???????????s2 = s2.replace(mc.group(), res + ""); ???????} ???????return s2; ???}}调用的时候直接用calcu()就好
然后是对应的前台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('*')">×</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('/')">÷</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>他的css
html { ???font-size: 62.5%; ???box-sizing: border-box; ???margin: 0; ???padding: 0; ???box-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; ?box-shadow: 0 .3rem 3rem .1rem rgba(0,0,0,0.6); ?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;}长这个样子
用到了El表达式
相关jar包
xml配置
<?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>对应的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, HttpServletResponse resp) throws ServletException, IOException { ???????????String result = req.getParameter("result"); ???// ?req.setAttribute("result", "admin"); ???????String finalRes = result; ???????result = finalRes+UtilArithmetic.calcu(result); ???????????????HttpSession session = req.getSession(); ???????session.setAttribute("count",result); ???????System.out.println(result); ???????req.getRequestDispatcher("index.jsp").forward(req, resp); ???} ???}最后是结构
晚安。
做个好梦
おやすみ～
基于Servlet+jsp的web计算器
原文地址：https://www.cnblogs.com/jsccc520/p/10325489.html