Untitled

My servlet code:``

package servlet;

import java.io.*;

import javax.servlet.*;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.sql.*;

public class MyServlet extends HttpServlet
{

    Connection con=null;

    public void init(ServletConfig config)
    {
        try{
            Class.forName("oracle.jdbc.driver.OracleDriver");
            String url="jdbc:oracle:thin:@localhost:1521:xe";
            String username="system";
            String password="manager";
            con=DriverManager.getConnection(url,username,password);
            if(con!=null){
                System.out.println("connetion established");
            }
        }catch(Exception e){
            e.printStackTrace();
        }
    }

public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{


String username=request.getParameter("username");

        String password=request.getParameter("password");

        String email=request.getParameter("email");
        String x=request.getParameter("phone");
        long phone=0;
        if(x!=null){
            phone =Long.parseLong(x);
                }
    try {
            PreparedStatement ps=con.prepareStatement("insert into students values(?,?,?,?)");
            ps.setString(1, username);
            ps.setString(2,password);
            ps.setString(3,email);
            ps.setLong(4, phone);
            ps.executeUpdate();

            }catch(Exception e){
                    e.printStackTrace();
                }

PrintWriter pw=response.getWriter();
    pw.println("<html><body bgcolor='powderblue'><center>");
    pw.println(username+"registered succesfully");
    pw.println("</center></body></html>");
            }
}

here my html codes starts

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Welcome</title>
</head>
<body>
<form action="./register" name="ureg" style="position: relative;left: 110px;" method="post" onsubmit="return validation()">
<!--                  USERNAME:<br>-->
ENTER USERNAME:<BR>
<input type="text" name="username" placeholder="Enter username"><br></br>
<!--                  PASSWORD:<br>-->
ENTER PASSWORD:<BR>
<input type="password" name="password" placeholder="Enter password"><br></br>
ENTER MAIL:<BR>
<input type="email" name="email" placeholder="Enter your email"><br></br>
ENTER PHONE NO:<BR>
<input type="text" name="phone" placeholder="Enter your mobile no" maxlength="10"><br></br>

&nbsp;<input type="submit" id="but" value="Register"style="background-color: yellowgreen;color: #ffffff"/>
&nbsp;&nbsp;   <input type="reset"id="but" value="Reset" style="background-color: #AA3300;color: #ffffff"></input><br></br>

        </form>


</body>
</html>


My xml file:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>Practice1</display-name>
  <welcome-file-list>
    <welcome-file>register.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
  <servlet-name>registerapp</servlet-name>
  <servlet-class>MyServlet</servlet-class>

  </servlet>
  <servlet-mapping>
  <servlet-name>registerapp</servlet-name>
  <url-pattern>/register</url-pattern>
  </servlet-mapping>
</web-app>