晚安社区， 这是我的第一篇文章，所以首先，我要感谢大家的辛勤工作。
我在Servlet中的会话出现了问题（也许答案也很容易，我现在无法“看到”它。）
Servlet 1。
public void init() {
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
getCustomerIdFromSessionRequest(request);
out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet</title>");
out.println("</head>");
out.println("<body>");
String action = request.getParameter("action");
if (action != null && action.equals("addArticle")) {
String articleId = request.getParameter("ArticleId");
if (articleId != null) {
Article article = shop.getArticle(Integer.parseInt(articleId));
printAddedArticle(article);
cart.addCartItem(article);
}
}
printCatalog();
}
private Integer getCustomerIdFromSessionRequest(HttpServletRequest request) {
HttpSession session = request.getSession();
session.setAttribute("de.leuphana.webshop.customerId", session.getId());
session.setAttribute("de.leuphana.webshop.cart", cart.getCartItems());
return customerId;
}
Servlet 2
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
HttpSession session = request.getSession(false);
String customerId=(String)session.getAttribute("de.leuphana.webshop.customerId");
Cart cart=(Cart)session.getAttribute("de.leuphana.webshop.cart");
System.out.println(customerId);
System.out.println(cart.getNumberOfArticles());
System.out.println(cart.getCartItems());
out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Cart</title>");
out.println("</head>");
out.println("<body>");
printCart(cart);
out.println("</br><a href=\"showCatalog\"> Show Catalog </a>");
out.println("</body>");
out.println("</html>");
}
ATM我收到消息： 消息java.util.HashMap $ Values无法转换为de.leuphana.shop.structure.Cart
现在我无法确切地找出问题所在。
在此我可以阅读一些有关此主题的信息，提示，评论或链接，谢谢。
最好的问候
e：消息用于servlet 2行 购物车cart =（Cart）session.getAttribute（“ de.leuphana.webshop.cart”）;