Download - Sessionex1
SiteHome.html<html> <head> <title>URL Rewriting Example</title> </head> <body>
This is the Home page for the example to demonstrate how to use <BR>
URL Rewriting and Hidden form fields to mantain the client state. <BR><BR>
<a href="Login.html">Login</a> </body></html>
Login.html<html> <head> <title>URL Rewriting Example</title> </head> <body> <form name="loginform" action="login" method="post"> <table border="0"> <tr> <td>UserName:</td> <td><input type="text" name="uname"></td> </tr> <tr> <td>Password:</td> <td><input type="password" name="password"></td> </tr> <tr> <td colspan="2" align="center"><input type="submit"></td> </tr> </table> </form> </body></html>
• Once you click on submit button• Post method is executed, data is submitted
into server in the form of request object• Later LoginServlet program gets executed
because of <form action=“login”> whose url pattern servlet name is “LoginServlet” (see web.xml file)
LoginServlet.javapackage com.rajendra.servlets;
import java.io.IOException;import java.io.PrintWriter;
import javax.servlet.*;import javax.servlet.http.*;
public class LoginServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
String uname=request.getParameter("uname");String pass=request.getParameter("password");
LoginServlet.java
response.setContentType("text/html");PrintWriter out = response.getWriter();out.println("<HTML>");out.println(" <HEAD><TITLE>A
Servlet</TITLE></HEAD>");out.println(" <BODY>");
LoginServlet.javaif (uname==null||uname.equals("")){
out.println("<b><i>Username Cannot be empty</i></b>");RequestDispatcher rd=request.getRequestDispatcher("/Login.html");rd.include(request, response);return;}if (pass==null||pass.equals("")){out.println("<b><i>Password Cannot be empty</i></b>");RequestDispatcher rd=request.getRequestDispatcher("/Login.html");rd.include(request, response);return;}
UserDAO ud=new UserDAO();
LoginServlet.javaif(ud.validate(uname,pass)){
out.println("<table width=98% height=95% border=1><tr>");out.println("<td height=45 colspan=2 align=center><font size=5>My Email Site</font></td>");out.println("</tr><tr>");out.println("<td width=12% height=545 align=center valign=top>");out.println("<p> </p><p><font size=4>");out.println("<a href='inbox?uname="+uname+"'>InBox</a>");out.println("</font></p>");out.println("<p><font size=4>Bulk Mail</font></p>");out.println("<p><font size=4>Sent Items</font></p>");out.println("<p><font size=4>Write Mail</font></p>");out.println("<p><font size=4><a href='Login.html'>Logout</a></font></p>");out.println("<p> </p></td>");out.println("<td width=88% align=left valign=top><p> </p>");out.println("<p><font size=4>Welcome, "+uname+"</font></p></td>");out.println("</tr><tr align=center>");out.println("<td colspan=2><div align=center>@Copyrights 2001-08</div></td>");out.println("</tr></table>");
LoginServlet.java}//if
else{out.println("<b><i>Username or Password given are not valid</i></b>");RequestDispatcher rd=request.getRequestDispatcher("/Login.html");rd.include(request, response);return;
}out.println(" </BODY>");out.println("</HTML>");out.flush();out.close();
}
}
• Now servlet container calls the public service() and which intern calls the protected service() method
• Protected service() calls doPost() method
• Now if() conditions becomes false, (server side validation for username and password).
• Now UserDao object is created to call validate() method
LoginServlet.java
if(ud.validate(uname,pass))
• if(ud.validate(uname,pass))• if(ud.validate(rajendra,raj)) method calling• Now control goes to validate () method in
UserDao class
UserDAO.javapackage com.rajendra.servlets;import java.sql.*;public class UserDAO {
public boolean validate(String uname, String pass){
try {Connection con=DriverConnection.getConnection();Statement st=con.createStatement();ResultSet rs=st.executeQuery("select count(*) from userdetails where uname=\'"+uname+"\' and pass=\'"+pass+"\'");return rs.next();}//trycatch(Exception e){e.printStackTrace();}return false;}
}
• return rs.next();• return true;//it returns true as resultset
contains next element• Now control come back to the
LoginServlet.java
if(ud.validate(uname,pass)){ //if condition becomes trueout.println("<table width=98% height=95% border=1><tr>");out.println("<td height=45 colspan=2 align=center><font size=5>My Email Site</font></td>");out.println("</tr><tr>");out.println("<td width=12% height=545 align=center valign=top>");out.println("<p> </p><p><font size=4>");out.println("<a href='inbox?uname="+uname+"'>InBox</a>");out.println("</font></p>");out.println("<p><font size=4>Bulk Mail</font></p>");out.println("<p><font size=4>Sent Items</font></p>");out.println("<p><font size=4>Write Mail</font></p>");out.println("<p><font size=4><a href='Login.html'>Logout</a></font></p>");out.println("<p> </p></td>");out.println("<td width=88% align=left valign=top><p> </p>");out.println("<p><font size=4>Welcome, "+uname+"</font></p></td>");out.println("</tr><tr align=center>");out.println("<td colspan=2><div align=center>@Copyrights 2001-08</div></td>");out.println("</tr></table>");
