by Dinesh Thakur Category: Servlet with MySql Database

This Function will Returns the value of one expression raised to the power of another expression.

First i made a database named 'dbase' within the complete reference of mySql(php myAdmin).Then i import all the required java package from java library as program need. Then after i made a class named 'MySqlPOWFunction' that is been extends the 'HttpServlet'. Then i use to get request from doGet()method the serviceMethod() for output on web browser. Then i loaded all the mandatory drivers for database accessing. After then the next move is to declare variables like i use 'connection' this will use to make a bridge or link between database and the actual code(java code).after then i use 'resultSet' that will be responsible for the getting value from the selected columns and rows. Then i use 'preparedStatement' this will use to executing the selected query like executeQuery as (Select POW(7,2)). In the last i use doGet() method that will bring the output on the web browser.

To get output on the web browser i use 'HTML' code and tags which present it 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 MySqlPOWFunction 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 POW(7,2)");
                   rs = ps.executeQuery();
               String title = "Using POW 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</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>MySqlPOWFunction</servlet-name>
   <servlet-class>MySqlPOWFunction</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
   <servlet-name>MySqlPOWFunction</servlet-name>
   <url-pattern>/MySqlPOWFunction</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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