LoginServlet.java

package iprog;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.mysql.jdbc.Driver;

/**
 * Servlet implementation class LoginServlet
 */
public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public LoginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {		
		doPost(request, response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		HttpSession session = request.getSession();
	
		String name =request.getParameter("name");
		String pwd =request.getParameter("pwd");
		
		PrintWriter out = response.getWriter();
		if (!(name==null)&&!(pwd==null)){
			Connection con = null;
			Statement stmt = null;
		
			try {
				Class.forName ("com.mysql.jdbc.Driver");
				con = DriverManager.getConnection( "jdbc:mysql://localhost/iprogusers?user=root&password=");
			
				String qry = "SELECT * FROM users WHERE username='"+name+"' AND userpass='"+pwd+"';";
				
				stmt = con.createStatement();
				ResultSet rs = stmt.executeQuery( qry );
				
				if (rs.first())
					session.setAttribute("user", name);
				
				else out.println("This is not a valid user'");
				
				stmt.close();
		
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (ClassNotFoundException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			finally{
				try {
					stmt.close();
				} catch (SQLException e) {
					// do nothing
				}
				try {
					con.close();
				} catch (SQLException e) {
					// do nothing
				}
				
			}

		}
		
		
		if (!(session.getAttribute("user")==null)){
			out.println("Hello "+session.getAttribute("user")+"<br>");
			out.println("IP Address: "+ request.getRemoteAddr()+"<br>");
			Cookie[] cookies = request.getCookies();
			int visits = 0;
			String action = request.getParameter("reset");
			if (!(action==null)&&action.equals("Reset")){
				Cookie visitCookie = new Cookie("visits", "");
				visitCookie.setMaxAge(0);
				response.addCookie(visitCookie);
			}
			else{
				try{
					for (int i=0;i<cookies.length;i++)
						if (cookies[i].getName().equals("visits"))
							visits = Integer.parseInt(cookies[i].getValue());
					visits++;
				}
				catch (NullPointerException ex){
					
				}
				Cookie visitCookie = new Cookie("visits", visits+"");
				response.addCookie(visitCookie);
			}
			out.print("You have visited this page "+ visits+" times<br>");
			out.print("<FORM METHOD=GET action = LoginServlet> ");
			out.print("Reset Counter : <INPUT TYPE=SUBMIT NAME=reset VALUE=Reset>");
			out.print("</FORM>");
		}
		out.print("<a href = guestbook.jsp>Guest book </a>");
		
	}

	}