欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  IT编程

基于Servlet+jsp的web计算器

程序员文章站 2022-04-28 12:45:51
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 ......

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.....)

基于Servlet+jsp的web计算器

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('*')">&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>

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

基于Servlet+jsp的web计算器

用到了el表达式

相关jar包

基于Servlet+jsp的web计算器

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

基于Servlet+jsp的web计算器

晚安。

做个好梦

おやすみ~