by Dinesh Thakur Category: Servlet with MySql Database

This function will show that the expression value’s are Equal or Not.

First of all i made a database named 'dbase' within the reference of mySql(php myAdmin).here i also import required java packages from java library. Then after i made a class named 'MySqlEQUALFunction' which extends 'HttpServlet'. Then i use service()Method that will bring request from the doGet()Method for output. Just before declaring variable I loaded all the required drivers that are necessary for database accessing. Then after i use variable like i use 'connection' for creating a link between database and java code. Other i use 'resultSet' that will do the required job to fetch value from the selected columns and rows. Other one is 'preparedStatement' that will use to executing the selected Query like executeQuery() as (SELECT 1=2). In the last phase i use doGet()Method that will present output on the web browser.

I use 'HTML' code and some of these tags that will provide the output on the web browser 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 MySqlEQUALFunction 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 1=2");
              rs = ps.executeQuery();
              String title = "Using EQUAL  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>MySqlEQUALFunction</servlet-name>
   <servlet-class>MySqlEQUALFunction</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
   <servlet-name>MySqlEQUALFunction</servlet-name>
   <url-pattern>/MySqlEQUALFunction</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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