by Dinesh Thakur Category: Servlet with MySql Database

This Function Will Returns the base-2 logarithm of the passed numeric expression.

I use to made a database first named 'dbase' within the reference of mySql(php myAdmin). Then i import all important java packages from java library. Then i made a class named ' MySqlLOG2Function' extends 'HttpServlet'. Then i use service()Method this will be responsible for the getting the request from the doGet()Method for output. Then i loaded all the required drivers for the database accessing. Then i use to set variables like i use first variable 'connection' that will be responsible for the creating a link between database and the java code. Then i use 'resultSet' this will use to get value from the selected columns and the rows from table. I use here 'preparedStatement' that use to executing the selected query like executeQuery() as (Select LOG2(512)). Then in last phase i use doGet()Method that will provide the output on the web browser.

To feel look good the result we use a tabular form concept. For this kind of requirement, we use ‘HTML’ coding and some of tags to use Output in Designer look to show on a web browser.

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 MySqlLOG2Function 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 LOG2(512)");
                   rs = ps.executeQuery();
                String title = "Using LOG2(LOGRITHM) 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>MySqlLOG2Function</servlet-name>
   <servlet-class>MySqlLOG2Function</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
   <servlet-name>MySqlLOG2Function</servlet-name>
   <url-pattern>/MySqlLOG2Function</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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