GDPU JavaWeb mvc模式

搭建一个mvc框架的小实例。

简易计算器

有一个名为inputNumber.jsp的页面提供一个表单，用户可以通过表单输入两个数和运算符号提交给Servlet控制器；由名为ComputerBean.java生成的JavaBean负责存储运算数、运算符号和运算结果，由名为handleComputer的servlet控制器负责运算，将结果存储到JavaBean中，并负责请求JSP页面lookResult.jsp显示JavaBean中的数据。

inputNumber.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<p>输入运算数、选择运算符</p>
<form action="handleComputer" method="post">
    <input type="text" name="numberOne" />
    <select name="operator">
        <option value="+">+</option>
        <option value="-">-</option>
        <option value="*">*</option>
        <option value="/">/</option>
    </select>
    <input type="text" name="numberTwo" /><br>
    <input type="submit" value="计算"/>
</form>
</body>
</html>

ComputerBean

package Beans;

public class ComputerBean {
    private double num1, num2, result;
    private String opt;

    // 省略部分setter和getter方法

    public double getNum1() {
        return num1;
    }

    public void setNum1(double num1) {
        this.num1 = num1;
    }

    public double getNum2() {
        return num2;
    }

    public void setNum2(double num2) {
        this.num2 = num2;
    }

    public double getResult() {
        return result;
    }

    public void setResult(double result) {
        this.result = result;
    }

    public String getOpt() {
        return opt;
    }

    public void setOpt(String opt) {
        this.opt = opt;
    }

    public double optResult(String opt, double num1, double num2) {
        if (opt.equals("+")) {
            result = num1 + num2;
        }
        if (opt.equals("-")) {
            result = num1 - num2;
        }
        if (opt.equals("*")) {
            result = num1 * num2;
        }
        if (opt.equals("/")) {
            result = num1 / num2;
        }
        return result;
    }
}

handleComputer

import Beans.ComputerBean;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/handleComputer")
public class handleComputer extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        double num1 = Double.parseDouble(request.getParameter("numberOne"));
        double num2 = Double.parseDouble(request.getParameter("numberTwo"));
        String operator = request.getParameter("operator");
        ComputerBean computerBean = new ComputerBean();
        computerBean.setNum1(num1);
        computerBean.setNum2(num2);
        computerBean.setOpt(operator);
        double result = computerBean.optResult(operator, num1, num2);
        computerBean.setResult(result);
        request.setAttribute("computerBean", computerBean);
        RequestDispatcher dispatcher = request.getRequestDispatcher("lookResult.jsp");
        dispatcher.forward(request, response);
    }
}

lookResult.jsp

<%@ page import="Beans.ComputerBean" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%--EL表达式--%>
<p>${computerBean.num1}${computerBean.opt}${computerBean.num2}=${computerBean.result}</p>
<%--JSP--%>
<%
//    ComputerBean computerBean = (ComputerBean) request.getAttribute("computerBean");
%>
<%--<%= computerBean.getNum1() %><%= computerBean.getOpt() %><%= computerBean.getNum2() %> = <%= computerBean.getResult() %>--%>
</body>
</html>