Question

我有一个使用Session的Shopping Cart项目并将数据插入数据库。我的showCart.jsp：

<html>
<body>
<h1>Shopping Cart Details</h1>
<table width=50%>
<tr><td>Item ID</td><td>Number of item in Shopping Cart</td></tr>
<%
    java.util.Enumeration em = session.getAttributeNames(); 
    for(;em.hasMoreElements();){
       String id= em.nextElement().toString();
    //get value from session object (see HttpSession)
       String count=session.getAttribute(id).toString();
       out.println("<tr>");
       out.println("<td>"+id+"</td>");
       out.println("<td>"+count+"</td>");
       out.println("</tr>");
    }
%>
</table>
<h2><a href="itemList.jsp">Items List</h2>
<br>
<h2><a href="checkout.jsp">Check-out</h2>

</body>
</html>

在我的showCart.jsp中，它负责获取用户请求的产品（addtoCart）并显示它。在我的Checkout.jsp

中

<%@page import="DAO.DAO_Product"%>
<%@page import="Entity.Product"%>
<html>
<body>
<h1>Checkout!</h1>
<%
    DAO_Product dao = new DAO_Product();
    int count = Integer.parseInt(request.getParameter("count"));
    int id = Integer.parseInt("id");
    Product pro = new Product(id,count);
    int n = dao.addBill(pro);
    if(n>0){
        out.println("Your request has been approved");
    }
    session.invalidate();
 %>

 <h2><a href="itemList.jsp">New Shopping Cart</h2>


 </body>
 </html>

在checkout.jsp中，它将使会话无效并将数据插入数据库（客户请求的数据库）。我的问题是：我无法插入“count”参数，并抛出异常：

org.apache.jasper.JasperException: java.lang.NumberFormatException: null
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServlet    Wrapper.java:548)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.jav    a:471)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
root cause

java.lang.NumberFormatException: null
java.lang.Integer.parseInt(Integer.java:454)
java.lang.Integer.parseInt(Integer.java:527)
org.apache.jsp.checkout_jsp._jspService(checkout_jsp.java:73)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.jav    a:433)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

有什么想法解决我的问题吗？谢谢。

使用JSP创建购物车并将数据插入数据库

0 个答案: