by Dinesh Thakur Category: Servlet with MySql Database

This function will repeat a string the specified number of times.

First we make a table in database named 'dbase' with required fields with in the reference of mySql(php myAdmin). Next step will be to import the required packages from the java library. After then we make a class named ‘MySqlREPEATFunction’, which is, extends the 'HttpServlet'. And then we use serviceMethod() which will access the granting for getting request from doGet()Method. Then load all the required Drivers. After, that we declare some mandatory variable to access control on the program like Connection (The Connection variable will be used to create a link between the database and the actual code (backend and the frontend). The other variable is resultset this variable is responsible for the fetching value from required columns and rows. And the last variable known as preparedStatement is used to execute the query like executeQuery() as (Select REPEAT('MYSQL',4)).and to present the output we use doGet()Method which provide the output on the Web Browser.

While executing the output on web browser i use 'HTML' code and tags that will present the output in tabular form.

import java.io.IOException;

import java.io.PrintWriter;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MySqlREPEATFunction extends HttpServlet
   {
       public void service(HttpServletRequest rq, HttpServletResponse rp)throws IOException, ServletException
         {
              rp.setContentType("text/html");
              PrintWriter disp = rp.getWriter();
              String driver = "com.mysql.jdbc.Driver";
              String url = "jdbc:mysql://localhost/dbase";
              String uid = "root";
              String psw = "root";
              Connection con=null;
              PreparedStatement ps = null;
              ResultSet rs;
              try
               {
                   Class.forName(driver);
                   con = DriverManager.getConnection(url,uid,psw);
                   ps=con.prepareStatement("Select REPEAT('MYSQL',4)");
                   rs = ps.executeQuery();
               String title = "Using Repeat Function";
                   String docType ="<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";
              disp.println(docType + "<html>\n" + "<head><title>" + title + "</title></head>\n" +
                  "<body bgcolor=\"#f4efef\">\n" + "<h1 align=\"center\">" + title + "</h1>\n" + "<ul>\n" +
              "<table width=\"50%\" border=\"1\" align=\"center\">\n" + "<th>Value Is </th>\n"+ "</body> </html>");
                  while(rs.next())
                      {
                           String val = rs.getString(1);
                       disp.println("<tr><td align=\"center\">" + val +"</td></tr>" );  
                      }     
              }       
                       catch(Exception e) 
                          {
                          e.printStackTrace();
                          }
                          disp.close();
         }
                       public void doPost(HttpServletRequest rq,HttpServletResponse rp)throws IOException,ServletException
                                  {
                                     doGet(rq,rp);
                                  }
   }
WEB.xml
 
<servlet>
   <servlet-name>MySqlREPEATFunction</servlet-name>
   <servlet-class>MySqlREPEATFunction</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
   <servlet-name>MySqlREPEATFunction</servlet-name>
   <url-pattern>/MySqlREPEATFunction</url-pattern>
</servlet-mapping>




About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.



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