Servlet session: 用session实现简单购物车 – 小飞侠

Servlet session: 用session实现简单购物车

Post author:xfxia
Post published:2023年7月22日
Post category:其他

目录

listBookServlet

purcharseServlet

实现步骤

1. 创建 Book 封装图书信息

2. 创建 BookDB ，模拟数据库，里面保存图书

3. 提供图书的购买页面：listBookServlet

4. 添加购物车：purcharseServlet

5. 回显购物车信息：cartServlet

导航栏

Book

package chapter05.session;

public class Book {

	
	public String id;
	public String name;
	//alt + shift + s
		//构造有参 Generate constructors using fields...
		public Book(String id, String name) {		
			this.id = id;
			this.name = name;
		}
	
	//添加get、set方法 generate getters and setters
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	
	
}

BookDB

模拟数据库

package chapter05.session;

import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Map;

public class BookDB {
//模拟数据库
	private static Map<String,Book> map =new LinkedHashMap<String,Book>();
		static {
			map.put("1", new Book("1","第一战场指挥官"));
			//选中需要复制的，alt+ctrl+pgDn
			map.put("2", new Book("2","开端"));
			map.put("3", new Book("3","海岛基建日常"));
			map.put("4", new Book("4","吾友皆大佬"));
			map.put("5", new Book("5","荣誉老王"));
			map.put("6", new Book("6","赚钱真的好难哦!"));
	
		}
		
		//1.提供一个得到图书的方法
		public static Collection<Book> getAll(){
			return map.values();
		}
		//2.根据map的key，也就是图书id，得到图书
		public static Book getBook(String id) {
			return map.get(id);
		}
	
}

listBookServlet

package chapter05.session;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Collection;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 * 提供一个图书的界面
 */
@WebServlet("/listBookServlet")
public class listBookServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub	
		// 处理中文乱码
		response.setContentType("text/html;charset=utf-8");
		//1.得到所有图书
		Collection<Book> books = BookDB.getAll();
		//2.图书回显到页面
		PrintWriter out = response.getWriter();
		out.print("以下是本网站所售卖的所有图书："+"<br/><br/>");
		//3.遍历集合，图书显示
		for(Book b :books) {
			//4.得到图书的名称
			String url = "purcharseServlet?id="+b.getId();
			out.print("图书名称 ： 《"+b.getName()+"》           "+"<a href ='"+url+"'>点击购买</a><br>");			       
		}
}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

purcharseServlet

package chapter05.session;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 添加购物车
 */
@WebServlet("/purcharseServlet")
public class purcharseServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		// 处理中文乱码
		response.setContentType("text/html;charset=utf-8");
		//1.获取图书信息
		String id = request.getParameter("id");
		//判断id是否存在
		if(id==null) {
			//没有 购买图书
			response.sendRedirect("listBookServlet");
			return;
		}
		System.out.println();
		//2.图书已经购买
		Book book = BookDB.getBook(id);
		//3.把图书添加至购物车
		HttpSession session = request.getSession();
		List<Book> list = (List<Book>) session.getAttribute("cart");
		//4.判断购物车是否存在：是不是首次购买图书
		if(list==null) {//首次购买
			//创建购物车
			list = new ArrayList<Book>();
			//把购物车放进session
			session.setAttribute("cart", list);
			
		}
		//5.把图书添加到购物车
		list.add(book);
		//6.把请求跳转到CartServlet
		//session基于自己创建的cookie完成效果：在浏览器关闭后，cookie对象还存在/目的
		Cookie cookie = new Cookie("JESSIONID", session.getId());
		cookie.setMaxAge(60*30);//1h
		cookie.setPath("/chapter05.session");
		response.addCookie(cookie);
		
		//跳转到cartServlet里面		
		response.sendRedirect("/chapter03/cartServlet");
		//response.sendRedirect("cartServlet");		
		/**
		 * String url = "cartServlet";
	       response.sendRedirect(url);
		 */
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

cartServlet

package chapter05.session;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

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 javax.servlet.http.HttpSession;

/**
 * 回显图书信息
 */
@WebServlet("/cartServlet")
public class cartServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		// 处理中文乱码
		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();
		//1.得到购物车
		List<Book> cart = null;
		//2.得到用户自己的session
		HttpSession session = request.getSession(false);
		//3.自己定义一个标识，判断购物车里面是否有图书
		boolean cartFlag = true;
		if(session==null) {//购物车没有图书
			cartFlag = false;
		}
		else {
			cart = (List<Book>) session.getAttribute("cart");
			if(cart==null) {
				cartFlag=false;
			}
		}
		//4.判断购物车有商品
		if(!cartFlag) {//没有书
			out.print("对不起，您的购物车没有图书，请去购买。");			
		}
		else {
			//有图书，遍历图书
			out.print("购买图书如下： "+"<br/>");
			for(Book b:cart) {
				out.print("购买的图书："+b.getName()+"<br/>");
			}
			
		}
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

web.xml

<?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>chapter03</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>

<servlet>  
  	<servlet-name>book1</servlet-name>
  	<servlet-class>chapter05.session.listBookServlet</servlet-class>
  </servlet>  
  
  <servlet-mapping>
  	<servlet-name>book1</servlet-name>
  	<url-pattern>/test17</url-pattern>
  </servlet-mapping>
  
  
    <servlet>  
  	<servlet-name>book2</servlet-name>
  	<servlet-class>chapter05.session.purcharseServlet</servlet-class>
  </servlet>  
  
  <servlet-mapping>
  	<servlet-name>book2</servlet-name>
  	<url-pattern>/test18</url-pattern>
  </servlet-mapping>
  
    <servlet>  
  	<servlet-name>book3</servlet-name>
  	<servlet-class>chapter05.session.cartServlet</servlet-class>
  </servlet>  
  
  <servlet-mapping>
  	<servlet-name>book3</servlet-name>
  	<url-pattern>/test19</url-pattern>
  </servlet-mapping>


</web-app>

运行效果

版权声明：本文为weixin_54348877原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。

原文链接：https://blog.csdn.net/weixin_54348877/article/details/120835132