jsp练习 MVC（计算面积）

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package demo.controller;

import demo.service.Service;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ComputeServlet extends HttpServlet
{
    public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws IOException, ServletException
    {
        doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws IOException, ServletException
    {
        //1.接收圆的半径
        String r =  "";
        r = (String)request.getParameter("radius");

        if (r.equals("") || r == null)
        {
            //System.out.println("null");
            response.sendRedirect("index.jsp");//未输入圆的半径，返回输入页面
        }   

        else
        {
            double radius = Double.parseDouble(r);

            //2.计算圆的面积
            Service service = new Service();
            double area = service.computeArea(radius);

            String msg = "半径为：" + radius + "圆的面积为：" + area + "!";
            HttpSession session = request.getSession(true);//获取会话
            session.setAttribute("msg", msg);
            response.sendRedirect("showArea.jsp");
        }
    }
}

//服务层
package demo.service;

public class Service
{
    public double computeArea(double radius)
    {
        return Math.PI * radius * radius;
    }
}

<%@ page language="java" contentType="text/html; charset=GB2312" %>  
<html>
    <head> 
        <title> Servlet版本计算圆的面积</title>
        <style type="text/css">
            form, h1{
                text-align:center;
                color:#33ffcc;
            }
        </style>
    </head>
    <body>
        <h1> Servlet版本的计算圆的面积</h1>
        <form action="compute.action" method="post" onsubmit="return check()">
            请输入圆的半径：<input type="text" name="radius"/>
            <input type="submit" valur="计算"/>
        </form>
    </body>
</html>

<%@ page language="java" contentType="text/html; charset=GB2312" %>  
<html>
    <head>
        <title>Servlet版本的计算圆的面积</title>
        <style type="text/css">
            body{
                text-align:center;
                color:#00ffcc;
            }
        </style>
    </head>
    <body>
        <h1> Servlet版本的计算圆的面积</h1>
        <hr />
        <br />
        <%= (String)session.getAttribute("msg")%>
        <a href="index.jsp"> 返回继续 </a>
    </body>
</html>

<%@ page language="java" contentType="text/html; charset=GB2312" %>  
<html>
    <head>
        <title>MVC模式的注册登录系统</title>
        <style type="text/css">
            body{
                text-align:center;
                color:#0066ff;
            }
        </style>
    </head>
    <body>
        <h1>MVC模式的注册登录系统</h1>
        <hr />
        <br />
        <%= (String)session.getAttribute("msg")%>
        <a href="index.jsp">返回继续</a>
    </body>
</html>

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                      http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
  version="4.0" metadata-complete="true">

    <servlet>
        <servlet-name>computearea</servlet-name>
        <servlet-class>demo.controller.ComputeServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>computearea</servlet-name>
        <url-pattern>/compute.action</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

</web-app>

jsp练习 MVC（计算面积）

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