Session的实现例子

2019-11-06 06:01:59

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用session实现一个购物车

1.首先搭建web项目框架

目录为：

2.再来看看web.xml的配置

<?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_3_0.xsd"	id="WebApp_ID" version="3.0">	<display-name>session</display-name>	<welcome-file-list>		<welcome-file>/jsp/bookChose.jsp</welcome-file>	</welcome-file-list>	<servlet>		<servlet-name>shoppingcar</servlet-name>		<servlet-class>session.SessionShoppingCarSevlet</servlet-class>	</servlet>	<servlet-mapping>		<servlet-name>shoppingcar</servlet-name>		<url-pattern>/SessionShoppingCarSevlet</url-pattern>	</servlet-mapping>	<servlet>		<servlet-name>shoppinglist</servlet-name>		<servlet-class>session.ShoppingCarListServlet</servlet-class>	</servlet>	<servlet-mapping>		<servlet-name>shoppinglist</servlet-name>		<url-pattern>/ShoppingCarListServlet</url-pattern>	</servlet-mapping></web-app>3.代码的是实现
SessionShoppingCarSevlet.class
package session;import java.io.IOException;import java.util.HashMap;import java.util.Map;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class SessionShoppingCarSevlet extends HttpServlet {	PRivate static final long serialVersionUID = 1L;	@SuppressWarnings("unchecked")	@Override	protected void doPost(HttpServletRequest req, HttpServletResponse resp)			throws ServletException, IOException {		req.setCharacterEncoding("UTF-8");		resp.setContentType("text/html;charset = UTF-8");		// 获取会话对象		HttpSession session = req.getSession();		// 从会话域中获取shoppingCar属性对象		// 定义key为书名，value为数量		Map<String, Integer> shoppingCar = (Map<String, Integer>) session				.getAttribute("shoppingCar");		if (null == shoppingCar) {			shoppingCar = new HashMap<String, Integer>();		}		String[] books = req.getParameterValues("book");		if (books != null && books.length > 0) {			for (String bookname : books) {				// 判断书籍是否在购物车中				if (null == shoppingCar.get(bookname)) {					shoppingCar.put(bookname, 1);				} else {					shoppingCar.put(bookname, shoppingCar.get(bookname) + 1);				}			}		}		// 将更新后的购物车存储在会话域中		session.setAttribute("shoppingCar", shoppingCar);		resp.sendRedirect("http://localhost:8080/SessionExampleServlet/ShoppingCarListServlet");	}}
ShoppingCarListServlet类package session;import java.io.IOException;import java.io.PrintWriter;import java.util.Map;import java.util.Map.Entry;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class ShoppingCarListServlet extends HttpServlet {	private static final long serialVersionUID = 1L;	@Override	protected void doGet(HttpServletRequest req, HttpServletResponse resp)			throws ServletException, IOException {		this.doPost(req, resp);	}	@SuppressWarnings("unchecked")	@Override	protected void doPost(HttpServletRequest req, HttpServletResponse resp)			throws ServletException, IOException {		req.setCharacterEncoding("UTF-8");		resp.setContentType("text/html;charset = UTF-8");		PrintWriter out = resp.getWriter();		HttpSession session = req.getSession();		Map<String, Integer> shoppingCar = (Map<String, Integer>) session				.getAttribute("shoppingCar");		if (shoppingCar != null && shoppingCar.size() > 0) {			out.print("<p>您购买的书籍有：</p>");			for (Entry<String, Integer> book : shoppingCar.entrySet()) {				out.print(book.getKey() + "---" + book.getValue() + "本");			}		} else {			out.print("您还没有购买书籍");		}		out.print("<a href = 'http://localhost:8080/SessionExampleServlet/jsp/bookChose.jsp'>继续购买书籍</a>");	}}4.bookChose.jsp代码的实现<%@ page language="java" contentType="text/html; charset=UTF-8"	pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/htnl4/losse.dtd"><html><head><meta http-equiv="Content-Type" content="text/html;charset=UTF-8"><title>书籍选购</title></head><body>	<h3>请选择你的书籍</h3>	<form		action="http://localhost:8080/SessionExampleServlet/SessionShoppingCarSevlet"		method="post">		<p>			<input type="checkbox" name="book" value="javaSE 应用开发">javaSE			应用开发		</p>		<p>			<input type="checkbox" name="book" value="javaEE 应用开发">javaEE			应用开发		</p>		<p>			<input type="checkbox" name="book" value="javaWeb 应用开发">javaWeb			应用开发		</p>		<p>			<input type="submit" value="提交">		</p>	</form></body></html>