Question

这件事让我头疼了过去3天。我试图存储我从数据库中获得的结果集并存储在对象的arraylist中，然后将其传递给jsp进行显示，但是在运行程序之后，它给了我这个错误： enter image description here

任何人都知道如何解决这个问题？提前致谢！下面是我的代码： menu.java

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse     response)
        throws ServletException, IOException {
    PrintWriter out = response.getWriter();
    try {
        Class.forName("com.mysql.jdbc.Driver");

        //Create connection object
        conn = DriverManager.getConnection(request.getServletContext().getInitParameter("url"), request.getServletContext().getInitParameter("username"), request.getServletContext().getInitParameter("password"));
        String sql = "select name,price,imageurl from food";
        stmt = conn.createStatement();
        rs = stmt.executeQuery(sql);
        class food {

            String name;
            double price;
            String imageurl;

        }
        ArrayList<food> foodDetail = new ArrayList<food>();

        while (rs.next()) {
            food temp = new food();

            temp.name = rs.getString("name");
            temp.price = rs.getDouble("price");
            temp.imageurl = rs.getString("imageurl");

            foodDetail.add(temp);

        }
        request.setAttribute("menu", foodDetail);
        RequestDispatcher req = request.getRequestDispatcher("menu.jsp");
        req.forward(request, response);

    } catch (ClassNotFoundException ex) {
        Logger.getLogger(Menu.class.getName()).log(Level.SEVERE, null, ex);
    } catch (SQLException ex) {
        Logger.getLogger(Menu.class.getName()).log(Level.SEVERE, null, ex);
    } finally {

        try {
            rs.close();
            stmt.close();
            conn.close();
        } catch (SQLException ex) {
        }

    }

引入了menu.jsp

<%
        class food {

            String name;
            double price;
            String imageurl;
        }


        ArrayList<food> foodDetail = (ArrayList<food>) request.getAttribute("menu");
        food temp = new food();
java.util.Iterator it = foodDetail.iterator();
        while (it.hasNext()) {

            food z = (food) it.next();

            out.println(z.getName());


        }


    %>

Answer 1

尝试从jsp页面中删除此类food：

  class food {

        String name;
        double price;
        String imageurl;
    }

而是尝试在您的页面jsp中导入类似<%@ page import="package.food " %>的类食物。并在路径中添加反斜杠：

   RequestDispatcher req = request.getRequestDispatcher("/menu.jsp");

Answer 2

您尝试传递的列表ArrayList<food> foodDetail = new ArrayList<food>();中使用的servlet中的食物类正试图转换在jsp本身中定义的org.apache.jsp_menu$1food。删除类食物的jsp中的声明并使用<%@ page import="your.package.food" %>它应该与我在servlet中使用的声明相同。

将对象的arraylist从servlet传递给jsp失败

2 个答案: