使用session完成简单的购物功能。
大型的上午网站一般使用cookie来实现,目的是减少服务器的压力。
package cn.itcast.shoping;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.Serializable;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//代表首页的servlet
public class ListBookServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setCharacterEncoding("utf-8");//第一句,设置服务器端编码
response.setContentType("text/html;charset=utf-8");//第二句,设置浏览器端解码
PrintWriter writer = response.getWriter();
//1.输出网页所有商品
writer.println("本网站所有商品:<br>");
Map<String, Book> map = DB.getall();
for(Map.Entry<String, Book> entry :map.entrySet()){
Book book = entry.getValue();
writer.print("<a href='/web2/servlet/BuyServlet?id=" + book.getId()+"' target='_blank\'>" + book.getName()+"</a><br/>");
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
class DB{
private static Map<String,Book> map = new LinkedHashMap();
static {
map.put("1", new Book("1","java web开发","老张","一本好书"));
map.put("2", new Book("2","java jdbc开发","老张","一本好书"));
map.put("3", new Book("3","java spring开发","老a","一本好书"));
map.put("4", new Book("4","java struts开发","老v","一本好书"));
map.put("5", new Book("5","java android开发","老b","一本好书"));
}
public static Map getall(){
return map;
}
}
class Book implements Serializable{
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.itcast.shoping;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
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;
public class BuyServlet extends HttpServlet {
//完成购买
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String id = request.getParameter("id");
Book book = (Book) DB.getall().get(id);
HttpSession session = request.getSession();
//手动cookie 形式发送sessionid,以解决关闭浏览器后上次买的东西还在
String sessionid = session.getId();
Cookie cookie = new Cookie("JSESSIONID",sessionid);
cookie.setMaxAge(30*60);
System.out.println(request.getContextPath());
cookie.setPath(request.getContextPath());
response.addCookie(cookie);
//从session中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);
System.out.println(book.getName());
//request.getRequestDispatcher("/servlet/ListCarServlet").forward(request, response);
response.sendRedirect(request.getContextPath()+"/servlet/ListCarServlet");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
package cn.itcast.shoping;
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;
//显示用户购买的商品
public class ListCarServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setCharacterEncoding("utf-8");//第一句,设置服务器端编码
response.setContentType("text/html;charset=utf-8");//第二句,设置浏览器端解码
PrintWriter writer = response.getWriter();
HttpSession session = request.getSession(false);
if(session==null){
writer.println("您没有购买任何商品");
return;
}
writer.println("您购买了如下商品:<br/>");
List<Book> list = (List) session.getAttribute("list");
for (Book book:list){
writer.println(book.getName());
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}