Member Avatar for shilu2

HI All,
I have three tables tbl_category, tbl_subcategory, tbl_product . where categoryid is foreign key in subcategory table and subcategoryid is foreign key in prduct table. I want to show category and subcategory on home page menubar. I just reach upto display category on menubar but not able to get subcategory on mouseover of particular menu.

So I have a servlet to retrive data and jsp to display it.and jsp code is as below which can show only category.

<ul>
                <% Iterator itr;%>
               <% List data=(List)request.getAttribute("data");
                    for(itr=data.iterator(); itr.hasNext(); ){
                %>
                <li><a href=""><%=itr.next()%></a></li>
                <%}%>
                </ul>



can you please help me to show subcategory on mouseover
  • 2 Contributors
  • 4 Replies
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  • 3 Days Discussion Span
  • Latest Post Latest Post by shilu2

Dani AI

Generated

A simple, robust approach is to send a hierarchical menu from the servlet to the JSP and render it with JSTL/EL (avoid scriptlets). Build a model where each Category has a List of Subcategory objects (or a LinkedHashMap preserving order). You can either (A) fetch categories and subcategories in one LEFT JOIN, or (B) fetch categories first and subcategories in a second query. Option (A) is usually simpler and faster for a single menu load.

Example SQL (one-query approach):

SELECT c.id AS cat_id, c.name AS cat_name,
       s.id AS sub_id, s.name AS sub_name
FROM category c
LEFT JOIN subcategory s ON s.category_id = c.id
ORDER BY c.name, s.name;

Server-side: iterate the ordered ResultSet and assemble a List<Category> (create a new Category only when the category id changes; append subcategories to its list). Put that List as a request attribute, e.g. request.setAttribute("categories", categories); and forward to the JSP.

JSP (JSTL/EL) pattern to render nested <ul>/<li>:

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<ul class="menu">
  <c:forEach var="cat" items="${categories}">
    <li>
      ${cat.name}
      <c:if test="${not empty cat.subcategories}">
        <ul class="submenu">
          <c:forEach var="sub" items="${cat.subcategories}">
            <li><a href="products.jsp?sub=${sub.id}">${sub.name}</a></li>
          </c:forEach>
        </ul>
      </c:if>
    </li>
  </c:forEach>
</ul>

Minimal CSS for mouseover submenu:

.menu, .menu ul { list-style:none; margin:0; padding:0; }
.menu .submenu { display:none; position:absolute; }
.menu li:hover > .submenu { display:block; }

Quick troubleshooting notes: remove the extra call you make after forwarding (do not call another response writer or processRequest after RequestDispatcher.forward), use PreparedStatement and try-with-resources (or a pool), and avoid printing HTML from the servlet. As observed, this belongs in the JSP/Servlet area; implementing the hierarchical model + JSTL will produce the desired mouseover submenus for .

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All 4 Replies

Member Avatar for poojavb

May be u shud post this code under jsp section....

in this section we can help u with queries

Member Avatar for shilu2

Here is my servlet code

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Category extends HttpServlet {

    /**
     * Processes requests for both HTTP
     * <code>GET</code> and
     * <code>POST</code> methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            Class.forName("com.mysql.jdbc.Driver");
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet Category</title>");            
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet Category at " + request.getContextPath() + "</h1>");
            out.println("</body>");
            out.println("</html>");
        }catch(ClassNotFoundException cne){
        } finally {            
            out.close();
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP
     * <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out=response.getWriter();
        ArrayList list=new ArrayList();
        try{
            Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/store?user=shilpa&password=password");
            String query="select category_id,category_name from tbl_category";
            Statement st1=con.createStatement();
            ResultSet rs=st1.executeQuery(query);
            while (rs.next()) {
                //list.add(rs.getInt("category_id"));
                list.add(rs.getString("category_name"));          
             }
            request.setAttribute("data",list);
          RequestDispatcher rd=request.getRequestDispatcher("category.jsp");
          rd.forward(request, response);
        processRequest(request, response);
        }catch(Exception e){

        }
    }

    /**
     * Handles the HTTP
     * <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}

Here is jsp code

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@page language="java" import="java.util.*" %>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
             <ul>
                  <% Iterator itr;%>
                  <% List data=(List)request.getAttribute("data");
                     for(itr=data.iterator(); itr.hasNext(); ){
                   %>
                   <li><a href=""><%=itr.next()%></a></li>
              <%}%>
             </ul>

                <%}%>
          </body>
</html>

Which shows result category name from category table only but I want subcategory too on mouseover...
Thank you

Member Avatar for poojavb

This is VB.net section.... Servlet comes in Java....
This is not the correct section to post the code dear.....

Member Avatar for shilu2

so can I change tags ?

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