by Dinesh Thakur Category: Servlet with MySql Database

The 'ATAN' function will return the arctangent value of a numeric expression.

First i make a table in database named 'dbase' with required fields and values in it and within the reference of mySql(Php Admin).then i import all the required java package from java library. I made a class named 'MySqlATANFunction' extends the 'HttpServlet'. Then i use serviceMethod() which will bring the request from doGet()Method for Output. Then i load all the drivers for database accessing. after then i declare variables which are necessary for database conditions like i declare connection(this variable will use to make a link between database and java code or actual code).after then i declare resultset (this variable will use to get the values from desired columns and rows as required from query). The next one will be the preparedStatement (this variable will responsible for the executing query like executeQuery() as (Select ATAN('1')).in the last i used the doGet()Method which will bring the output on the web Browser.

On the web Browser for getting output in the manner way i used 'HTML' tags which 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 MySqlATANFunction 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 ATAN('1')");
         rs = ps.executeQuery();
             String title = "Using ATAN 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>MySqlATANFunction</servlet-name>
   <servlet-class>MySqlATANFunction</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
   <servlet-name>MySqlATANFunction</servlet-name>
   <url-pattern>/MySqlATANFunction</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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