ProductListServlet.java

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package sit.int303.webpro.classicmodels.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.PersistenceUnit;
import javax.persistence.Query;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import sit.int303.webpro.classicmodels.model.Products;

/**
 *
 * @author INT303
 */
@WebServlet(name="ProductListServlet",urlPatterns={"/ProductList"})
public class ProductListServlet extends HttpServlet {

    @PersistenceUnit(unitName = "sit.int303.webpro_ClassicModelsWebApp_war_1.0-SNAPSHOTPU")
    /**
     * 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 {
        String searchParam = request.getParameter("searchParam");
        if (searchParam == null || searchParam.trim().length() == 0) {
            request.setAttribute("message", "Please enter part of product name");
            doGet(request, response);
            return;

        }
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("sit.int303.webpro_ClassicModelsWebApp_war_1.0-SNAPSHOTPU");
        EntityManager em = emf.createEntityManager();
        Query qry = em.createQuery("SELECT p FROM Products p");//ชื่อคลาสที่อยู่ใน entity "Product"
        List<Products> pd = qry.getResultList();
        request.setAttribute("products", pd);
        request.getRequestDispatcher("/ProductList.jsp").forward(request, response);
    }

    // <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 { // คอยสังเกตอย่าให้มี รีเควสตีกลับมาไม่งั้นจะทำให้แฮงค์
        request.getRequestDispatcher("/ProductList.jsp").forward(request, response);
    }

    /**
     * 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>

}