Retrieving record from database in Java by using select option tag

Question

I want to retrieve record from database by clicking on the option selected from drop down list and it as a table on the web page. But after implementing following code the web page is blank now what should I do? Any type of help will be appreciable. Here is my index.jsp page:

<%@page contentType="text/html" pageEncoding="UTF-8"%>


    
        
        JSP Page
    
    
        
            Name of the Book :

And here is my servlet page for retrieving data from database

package com;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
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 portal extends HttpServlet {

    /**
     * Processes requests for both HTTP GET and POST
     * 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 {
            String book = request.getParameter("book");
            Class.forName("com.mysql.jdbc.Driver");
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql", "root", "password");
            PreparedStatement pt = conn.prepareStatement("Select * from book where Book_Name = ?");
            pt.setString(1, book);
            out.print("");
            out.print("Welcome To The Portal");
            ResultSet rs = pt.executeQuery();
            ResultSetMetaData rsd = rs.getMetaData();
            while (rs.next()) {
                out.print("");
                out.print("");
                out.print("");
                out.print("");
                out.print("");
                out.print("");
                out.print("");
                out.print("");
                out.print("");
                RequestDispatcher rd = request.getRequestDispatcher("logout.jsp");
                rd.include(request, response);
            }
            out.println("" + rsmd.getColumnName(1) + " " + rs.getString(1) + "
" + rsmd.getColumnName(2) + " " + rs.getString(2) + "
" + rsmd.getColumnName(3) + " " + rs.getString(3) + "
" + rsmd.getColumnName(4) + " " + rs.getString(4) + "");
        }

        catch (Exception e) {
            out.println(e);
        }
    }

    // 
    /**
     * Handles the HTTP GET 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 {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP POST 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";
    }// 

}

now I don't know where I miss something.

Taha · Accepted Answer

I suggest that you use your servlet as a controller that control the data in your application and not as a vue where you write html tags

this example may help you :

Firstly, create a serialisable java class where you put communicate with database :

public class BookData implements Serializable {

    private String ISBN;
    private String titre;
    private String auteur;
    private int ID;
    private String editeur;

    // ADD GETTER AN SETTER METHODS

    public BookData(String titre, String auteur, int ID, String editeur, String ISBN) {
        this.titre = titre;
        this.auteur = auteur;
        this.ID = ID;
        this.editeur = editeur;
        this.ISBN = ISBN;
    }

    public List loadData(String book) {
        List actorList = new ArrayList();

        com.mysql.jdbc.PreparedStatement ps = null;

        ResultSet rs = null;

        String url = "jdbc:mysql://127.0.0.1:3306/DATABASENAME";// CHANGE
        String name = "NAME";// CHANGE
        String pw = "PWD";// CHANGE
        String driver = "com.mysql.jdbc.Driver";

        Connection connexion = null;

        try {
            Class.forName(driver).newInstance();
            connexion = DriverManager.getConnection(url, name, pw);

            String q = "Select * from book where Book_Name ='" + book + "'";
            Statement commande = connexion.createStatement();
            rs = commande.executeQuery(q);

            while (rs.next()) {
                BookData bk = new BookData(rs.getString("Book_Title"), rs.getString("Book_Author"), rs.getInt("ID"),
                        rs.getString("Publisher"), rs.getString("ISBN"));/* CHANGE COLUMN NAMES */

                actorList.add(bk);
            }

            return actorList;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        } finally {
            try {
                rs.close();
                connexion.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

Secondly the servlet :

public class EXAMPLE_SERVLET extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        String option = request.getParameter("book");

        BookData dao = new BookData();
        List list = dao.loadData(option);

        request.setAttribute("booklist", list);

        RequestDispatcher view = request.getRequestDispatcher("test.jsp");
        view.forward(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

    }
}

then the JSP ((test.jsp))

 //...COLUMNS
        
            
                //...ROWS
            
    
        
            titre
    
    
        
                ${employee.titre}

Retrieving record from database in Java by using select option tag

Answers (2)

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