public class Products {
public Vector items=new Vector();
public Vector getItems() {
return items;
}
public Item getItems(String itemId){
int index=Integer.parseInt(itemId);
return (Item)items.elementAt(index);
}
public void setItems(Item item,String itemId) {
int index=Integer.parseInt(itemId);
items.set(index, item);
}
public Products(){
items.addElement(new Item("0",(float)59,"jsp应用开发详解",true,"电子工业出版社"));
items.addElement(new Item("1",(float)45,"java web服务开发",true,"电子工业出版社"));
items.addElement(new Item("2",(float)99,"java编程思想",true,"机械工业出版社"));
items.addElement(new Item("3",(float)10,"jsp编程指南",true,"电子工业出版社"));
items.addElement(new Item("4",(float)68,"J2EE应用开发详解",true,"电子工业出版社"));
items.addElement(new Item("5",(float)56,"J2EE企业级应用开发",true,"电子工业出版社"));
items.addElement(new Item("6",(float)56,"J2EE参考手册",true,"电子工业出版社"));
items.addElement(new Item("7",(float)55,"J2EE Web服务开发",true,"电子工业出版社"));
}
public int getSize(){
return items.size();
}
public void clear(){
items.clear();
}
}
<%@ page language="java" import="java.util.*,com.test.java.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<jsp:useBean id="products" class="com.test.java.Products" scope="page"/>
<jsp:setProperty name="products" property="*"/>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'shopping.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<form action="shop/cart.jsp" method="post">
<table width="75%" border=1 bordercolor="#006633">
<tr bgcolor="#999999"><td>id</td><td>名称</td><td>价格</td><td>是否有货</td>
<td>出版社</td></tr>
<%
Vector v=products.getItems();
Enumeration e=v.elements();
while(e.hasMoreElements()){
Item item=(Item)e.nextElement();
%>
<tr>
<td>
<input type="checkbox" name="itemId" value="<%=item.getItemId()%>">
</td>
<td><%=item.getDescription()%></td>
<td><%=item.getPrice() %></td>
<td><%=item.isAvailable() %></td>
<td><%=item.getProducer() %></td>
</tr>
<%}%>
<tr><td colspan=5><input type="submit" value="add" name="action"></td></tr>
<tr><td colspan=5><a href="shop/cart.jsp">购物车</a>[]<a href="shop/logout.jsp">注销</a></td></tr>
</table>
</form>
</body>
</html>
我第一次试的时候数据全部都是写的JSP应用开发详解,后来改成代码上写的数据,但是再次加载的时候显示的还是JSP应用开发详解,添加或删除都没反应。求解?

------解决方案--------------------
这个问题你可以试一试,然后你在重新部署一下,就没有问题了
你应该加上Products pro=new Products();
或者将你添加物品的代码写在静态代码块里面:
static{
items.addElement(new Item("0",(float)59,"jsp应用开发详解",true,"电子工业出版社"));
items.addElement(new Item("1",(float)45,"java web服务开发",true,"电子工业出版社"));
items.addElement(new Item("2",(float)99,"java编程思想",true,"机械工业出版社"));
items.addElement(new Item("3",(float)10,"jsp编程指南",true,"电子工业出版社"));
items.addElement(new Item("4",(float)68,"J2EE应用开发详解",true,"电子工业出版社"));
items.addElement(new Item("5",(float)56,"J2EE企业级应用开发",true,"电子工业出版社"));