by Dinesh Thakur Category: Servlet with MySql Database

The Function 'CHAR_LENGTH' will provide the numbers of character.

I make a table in database named 'dbase' within the reference of mySql(php myAdmin).then i import all the required java packages from java library.then i made a class named 'MySqlCHARLENGTHFunc' which extends 'HttpServlet'. After i loaded the all required drivers for accessing the database. Then i declare mandatory variables which will be used to connect with database completely. I first declare 'connection' this variable will be responsible for making a bridge between database and java code. Then i declare 'resultSet' that will use to bring the values from required columns and rows. I declare 'preparedStatement' that variable will be used to executing the selected query like executeQuery() as (Select CHAR_LENGTH('mysql')). Then i used doGet()method that will get the output on the web browser.

Now i used some kind of 'HTML' code and tags that will present the output in a tabular form on a web browser.

 
EXAMPLE
 
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 MySqlCHARLENGTHFunc 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 CHAR_LENGTH('mysql')");
        rs = ps.executeQuery();
            String title = "Using CHAR LENGTH 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>MySqlCHARLENGTHFunc</servlet-name>
   <servlet-class>MySqlCHARLENGTHFunc</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
   <servlet-name>MySqlCHARLENGTHFunc</servlet-name>
   <url-pattern>/MySqlCHARLENGTHFunc</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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