Java Web Session购物商店小实例

 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);
     }

 }