Calling Servlet to build a List of data from database and show this on the JSP page in table

In this example we are calling a servet to retrieve all the data from database and then add the data into list. The list is then added to the request object and sen to JSP page. On the JSP page this value is displayed.

This example illustrate how a servlet can be used to create a data list from database and how it can be added to the request object and sent to the JSP page. We are using tomcat to run and test the application

In our example "DataServlet.java" is the servlet which is making the connection to the database and retrieves the data from database. After getting the values from database, data is added to the Data List. Then data list is added to the request object and sent to the JSP page. In JSP page the values are displayed using Iterator class object.


import java.io.*;

import java.util.*;

import java.sql.*;

import javax.servlet.*;

import javax.servlet.http.*;



public class DataServlet extends HttpServlet{



  private ServletConfig config;

  //Setting JSP page

  String page="DataPage.jsp";



  public void init(ServletConfig config)

    throws ServletException{

     this.config=config;

     }

  public void doGet(HttpServletRequest request, HttpServletResponse response)

              throws ServletException,IOException
{

    

    PrintWriter out = response.getWriter();

    //Establish connection to MySQL database

    String connectionURL = "jdbc:mysql://192.168.10.59/messagepaging";

    Connection connection
= null;

    ResultSet rs;

    response.setContentType("text/html");

    List dataList
= new ArrayList(); 

      try {

       // Load the database driver

      Class.forName("com.mysql.jdbc.Driver");

      // Get a Connection to the database

      connection = DriverManager.getConnection(connectionURL, "root", "root"); 

      //Select the data from the database

      String sql = "select * from message";

      Statement s = connection.createStatement();

      s.executeQuery (sql);

      rs = s.getResultSet();

      while (rs.next ()){

        //Add records into data list

        dataList.add(rs.getInt("id"));

        dataList.add(rs.getString("message"));

      }

      rs.close ();

      s.close ();

      }catch(Exception e){

      System.out.println("Exception is ;"+e);

      }

      request.setAttribute("data",dataList);

      //Disptching request

      RequestDispatcher dispatcher = request.getRequestDispatcher(page);

      if (dispatcher != null){

        dispatcher.forward(request, response);

      } 

  }

}

For servlet to be invoked we have to do following entry in the web.xml file for servlet mapping.

1.Create and Save "DataServlet.java".
2.Compile that java file and place the DataServlet.class file into classes folder.
3.Do the servlet mapping in the web.xml
4.Create and Save "DataPage.jsp" and place it into appropriate folder.
5.Deploy the Tomcat Server.
6.Type following line in address bar "http://localhost:8080/JSPMultipleForms/DataServlet".