An example of using JSP to create a super simple web calculator-JS Tutorial-php.cn

An example of using JSP to create a super simple web calculator

高洛峰

Release： 2017-03-30 10:15:22

Original

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To implement a simple calculator program, requirements: use jsp+javabean mode.
The project source code is as follows:
File: calculator.jsp

<%@ page language="java" pageEncoding="UTF-8"%> 
<%@ page isErrorPage="true"%> 
<%@ page errorPage="calculator.jsp" %> 
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
 <head> 
  <title>简单的计算机</title> 
 </head> 
   
 <body> 
  <%--创建Calculator对象--%> 
  <jsp:useBean id="cal" class="cn.zq.domain.Calculator" /> 
  <%--设置值  通配符*表示设置所有属性--%> 
  <jsp:setProperty property="*" name="cal"/> 
    
    
  <%-- 
    进行计算 
   --%> 
   <c:if test="${empty pageContext.exception}"> 
    <% 
      cal.calculate(); 
    %> 
   </c:if> 
    
    
  <hr/> 
  <p>计算结果：${cal.firstNum } ${cal.operator } ${cal.secondNum } = ${cal.result }</p> 
  <hr/> 
    
  <%-- 
    构建url 
   --%> 
  <c:url var="formUrl" value="/calculator.jsp"/> 
  <form action="${formUrl }" method="post"> 
    <table border="1" cellpadding="2"> 
      <tr> 
        <td colspan="2" align="center">我的计算器</td> 
      </tr> 
      <tr> 
        <td>第一个参数:</td> 
        <td><input type="text" name="firstNum"/></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="secondNum"> 
        </td> 
      </tr> 
      <tr> 
        <td colspan="2"> 
          <input type="submit" value="计算" /> 
        </td> 
      </tr> 
    </table> 
  </form>   
 </body> 
</html>

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The javabean code used in this article is as follows:

package cn.zq.domain; 
  
public class Calculator { 
  private String firstNum; 
  private String operator; 
  private String secondNum; 
  private String result; 
  public String getFirstNum() { 
    return firstNum; 
  } 
  public void setFirstNum(String firstNum) { 
    this.firstNum = firstNum; 
  } 
  public String getOperator() { 
    return operator; 
  } 
  public void setOperator(String 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 Calculator() {} 
  public Calculator(String firstNum, String operator, String secondNum, 
      String result) { 
    this.firstNum = firstNum; 
    this.operator = operator; 
    this.secondNum = secondNum; 
    this.result = result; 
  } 
    
  public void calculate(){ 
    if(operator != null && !operator.equals("")){ 
      double first = new Double(firstNum); 
      double second = new Double(secondNum); 
      char oper = operator.charAt(0); 
      switch (oper) { 
      case &#39;+&#39;: 
        result = first + second + ""; 
        break; 
      case &#39;-&#39;: 
        result = first - second + ""; 
        break; 
      case &#39;*&#39;: 
        result = first * second + ""; 
        break; 
      case &#39;/&#39;: 
        result = first / second + ""; 
        break; 
      default: 
        throw new RuntimeException("未知运算符!"); 
      } 
    } 
  } 
}

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The final completed rendering is as follows:

An example of using JSP to create a super simple web calculator