javaWeb_08-用session实现简单的购物

首页

package com.rsl.Session;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.Serializable;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.Map;

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;

/**
 * Servlet implementation class SessionDemo8
 */
@WebServlet("/SessionDemo8")
public class SessionDemo8 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		//1,输出网站所有商品
		out.write("本网站有如下商品：");
		Map map = Db.getAll();
			/*for(Map.Entry entry:map.entrySet()){
				Book book = entry.getValue();
				out.print(book.getName()+""+"购买"+"");
				
			}*/
		/*----------------------------当用户禁用cookie之后哟这样写-------------------------------------*/
		//首先得到session
		request.getSession();
		for(Map.Entry entry:map.entrySet()){
			Book book = entry.getValue();
			String url = response.encodeURL("/day07/SessionDemo8_1?id="+book.getId());
			out.print(book.getName()+""+"购买"+"");
			
		}
		/*-----------------------------------------------------------------*/
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}

}

/*-------------------模拟数据库，存储书籍信息---------------------*/
class Db{
	private static LinkedHashMap map = new LinkedHashMap();
	static {
		map.put("1",new Book("1", "数学", "张三", "math"));
		map.put("2",new Book("2", "语文", "里斯", "chinese"));
		map.put("3",new Book("3", "英语", "王五", "english"));
		map.put("4",new Book("4", "化学", "赵六", "chemistry"));
	}
	public static Map getAll(){
		return map;
	}

}
/*-------------------维护对象---------------------*/
class Book implements Serializable{
	public Book() {
		super();
		// TODO Auto-generated constructor stub
	}
	public Book(String id, String name, String author, String description) {
		super();
		this.id = id;
		this.name = name;
		this.author = author;
		this.description = description;
	}
	private String id;
	private String name;
	private String author;
	private String description;
	
	
	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;
	}
	public String getAuthor() {
		return author;
	}
	public void setAuthor(String author) {
		this.author = author;
	}
	public String getDescription() {
		return description;
	}
	public void setDescription(String description) {
		this.description = description;
	}
}

中间处理页面

package com.rsl.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.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class SessionDemo8
 */
@WebServlet("/SessionDemo8_1")
public class SessionDemo8_1 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	String id = request.getParameter("id");
	Book book = Db.getAll().get(id);
	HttpSession session = request.getSession();
	//从session得到用户用于保存所有书的集合（购物车）；
	List list = (List) session.getAttribute("list");
	if(list == null){
		list = new ArrayList();
		session.setAttribute("list",list);
	}
	list.add(book);
	/*细节一：
	 * 使用转发会导致，重复刷新 ，重复提交表单
	 * request.getRequestDispatcher("/SessionDemo8_2").forward(request, response);
	*/
	//细节二：使用request.getContextPath()代替死板的工程名称
	//不禁用 response.sendRedirect(request.getContextPath()+"/SessionDemo8_2");
	
	
	/*----------------------------当用户禁用cookie之后哟这样写-------------------------------------*/
	String url = response.encodeRedirectURL(request.getContextPath()+"/SessionDemo8_2");
	response.sendRedirect(url);
	
	/*----------------------------end-------------------------------------*/
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}

}

显示结构页

package com.rsl.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;

/**
 * Servlet implementation class SessionDemo8_2
 */
@WebServlet("/SessionDemo8_2")
public class SessionDemo8_2 extends HttpServlet {
	private static final long serialVersionUID = 1L;
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		HttpSession session = request.getSession(false);
		if(session == null){
			out.write("您没有购买任何商品");
			return;
		}
		out.write("您购买了如下商品：");
		List list = (List)session.getAttribute("list");
		for(Book book:list){
			out.write(book.getName()+"");
		}
		
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}

}