JSP session.getAttribute異常錯誤

所以我試圖用會話製作購物車。如果我第一次添加一個項目，它會成功，但如果我添加另一個它會返回爲異常錯誤。（我已經宣佈session.setAttribute（「我」，「0」），當你登錄成爲會員）JSP session.getAttribute異常錯誤

這裏的doAddCart.jsp

<%@ page contentType="text/html; charset=utf-8" language="java" import="java.sql.*" errorPage="" %> 
<% 
    String id = request.getParameter("id"); 
    String qty = request.getParameter("qty"); 
    String temp = (String)session.getAttribute("i"); 
    int temp2 = Integer.parseInt(temp)+1; 
    session.setAttribute("i",temp2); 
    temp = Integer.toString(temp2); 
    session.setAttribute(temp,id); 
    session.setAttribute("q"+temp,qty); 
    response.sendRedirect("../product.jsp"); 
%>

這裏的錯誤，我得到

org.apache.jasper.JasperException: An exception occurred processing JSP page /Controller/doAddCart.jsp at line 5 

2: <% 
3: String id = request.getParameter("id"); 
4: String qty = request.getParameter("qty"); 
5: String temp = (String)session.getAttribute("i"); 
6: int temp2 = Integer.parseInt(temp)+1; 
7: session.setAttribute("i",temp2); 
8: temp = Integer.toString(temp2); 


Stacktrace:  org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)  org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) root cause 

java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String org.apache.jsp.Controller.doAddCart_jsp._jspService(doAddCart_jsp.java:68) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)  org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) note The full stack trace of the root cause is available in the Apache Tomcat/7.0.29 logs.

沒有人有解決這個問題嗎？

來源

2015-05-27 Kevin Fernando

這行假定會話[ 「我」]是一個字符串：

String temp = (String)session.getAttribute("i");

此行設置會話[ 「I」]爲Integer：

session.setAttribute("i",temp2);

刪除第7行並將其添加到底部，而不是將該屬性保留爲字符串：

session.setAttribute("i",temp);

來源

2015-05-27 19:52:10 Barett

但它不會執行增量。 – EJP

這解決了這個問題非常感謝你！ –

嘗試此線

session.setAttribute("i", String.valueOf(temp2));

來源

2015-05-27 19:50:50 Arjit

JSP session.getAttribute異常錯誤

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