Java Web　Session购物商店小范例

package cn.com.shopping;

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

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
//完成购买
public class BuyServlet 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=(Book)Db.getAll().get(id);
		//再加上那个关闭Cookie时session的剞劂方案
		//阻止session的时候解决方案
		
		HttpSession session=request.getSession(false);
		//从session中得到用户的保存所有书的集合（购物车）
		List list=(List)session.getAttribute("list");
		if(list==null)
		{
			list=new ArrayList();
			session.setAttribute("list", list);
		}
		list.add(book);
		
		String url=response.encodeRedirectURL("/Session/SessionCountDemo");
		response.sendRedirect(url);
	}

	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request,response);
	}

}
package cn.com.shopping;

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

//显示书
public class ListBookServlet 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();
		
		out.print("本店有如下的商品：<br/>");
		Map<String ,Book > map=Db.getAll();
		for(Map.Entry<String, Book> entry:map.entrySet())
		{
			Book book=entry.getValue();
			String url=response.encodeURL("/Session/BuyServlet?id="+book.getId());
			out.print(book.getName()+"<a href='"+url+"' target='_blank' >购买</a><br/>");
		}
		
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request,response);
	}

}
//Db作为数据库
class Db
{
	private static Map<String ,Book> map=new LinkedHashMap();
	static
	{
		map.put("1", new Book("1","Java WEB开发","WY","好书"));
		map.put("2", new Book("2","WEB开发","zt","一般"));
		map.put("3", new Book("3","程序设计","df","较好书"));
		map.put("4", new Book("4","计算机组成","as","一般好书"));
		map.put("5", new Book("5","编译原理","ty","很好书"));
		map.put("6", new Book("6","网络维护","hj","非常好书"));
	}
	
	public static Map getAll()
	{
		return map;
	}
}
//书
class Book
{
	private String id;
	private String name;
	private String author;
	private String description;
	
	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;
	}
	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;
	}
	
	
}
package cn.com.shopping;

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

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 SessionCountDemo 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();
		if(session==null)
		{
			out.write("您没买任何的商品！");
			return;
		}
		out.write("您购买了如下的商品：");
		List<Book> list=(List) session.getAttribute("list");
		for(Book book:list)
		{
			out.write(book.getName());
		}
		
	}

	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request,response);
	}

}