JSP与Servlet实现圆面积计算-优快云博客

本文链接：https://blog.youkuaiyun.com/beginner_C_P_P/article/details/84340066

题目：编写一个JSP页面，该页面提供一个表单，用户通过表单输入半径提交后，JSP页面将计算圆的面积的任务交给一个servlet去完成，并将计算结果存入session，在转向另一个JSP页面中显示结果。

输入界面Input.jsp

<%@ page contenType = "text/html;charset = gb2312"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
	<body bgcolor = cyan>
		<font size = 5>
			<form action = "Circle" method = post>
				请输入圆的半径：
				<input type = "text" name = "radius"><br>
				<input type = "submit" value = "提交" name = "submit">
			</form>
		</font>
	</body>
</html>

web.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
  <servlet>
    <servlet-name>Circle</servlet-name>
    <servlet-class>com.Servlet.Circle</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>Circle</servlet-name>
    <url-pattern>/Circle</url-pattern>
  </servlet-mapping>
</web-app>

Servlet文件

package com.Servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.*;
public class Circle extends HttpServlet {
	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		HttpSession session = request.getSession(true);
		request.setCharacterEncoding("gb2312");
		response.setContentType("text/html;charset=gb2312");
		PrintWriter out = response.getWriter();
		out.println("<html><body bgcolor = cyan>");
		try{
			double radius = Double.parseDouble
					(request.getParameter("radius"));
			double CircleArea = getArea(radius);
			session.setAttribute("CircleArea", CircleArea+"");
			request.getRequestDispatcher("Show.jsp").forward(request, response);
		}catch(Exception e) {
			e.printStackTrace();
			out.println("数据错误");
		}
		out.println("  </body>");
		out.println("</html>");
		out.flush();
		out.close();
	}
	public static double getArea(double radius){
		return radius*radius*3.14;
	}
}

输出文件Show.jsp

<%@page import="java.util.function.DoublePredicate"%>
<%@ page contentType="text/html; charset=gb2312" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
	<body bgcolor = cyan>
		<%
			double CircleArea = Double.parseDouble((String)session.getAttribute("CircleArea"));
			out.println("圆的面积为：" + CircleArea);
		 %>
	</body>
</html>

运行结果：
在这里插入图片描述