servlet

C:: Create a servlet demonstrating the use of session creation anddestruction. Also check whether the user has visited this page first time or has visited earlier also using sessions.
INPUT::

Index.html
<html>
<body>
<form action="session" method="get">
Enter User Id:<input type="text" name="txtName"><br>
<input type="reset" value="Reset">
<input type="submit" value="Submit">
</form>
</body>
</html>

Session.java
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.";
public class session extends HttpServlet
{
  public void doGet(HttpServletRequest req. HttpServletResponse res) throws IOException, ServletException
  {
    PrintWriter out-res.getWriter();
    out.println("<html><body>");
    HttpSession hs req.getSession(true);
    if(hs.isNew())
    {
      String name-req.getParameter("txtName");
      hs.setAttribute("uname", name);
      hs.setAttribute("visit","1");
      out.println("<h5>Welcome First Time</h5>");
    else
    {
      out.println("<h5>Welcome Again</h5>");
      int visit-Integer.parseInt((String)hs.getAttribute("visit"))+1;
      out.println("<h5>You visited "+visit+" times</h5>");
      hs.setAttribute("visit", visit);
    }
    out.println("<h5>Your Seesion Id "+hs.getId()+"</h5>");
    out.println("<h5>You Loged in at "+new java.util.Date(hs.getCreation Time())+"</h5>");
    out.println("<h5><a href=logoutservlet>Click to LOGOUT</a></h5>");
    out.println("</body>");
    out.println("</html>");
  }
}


wqlogoutServlet.java
package logoutservlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.*;
public class logoutservlet extends HttpServlet {
  public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException,   ServletException
  {
    PrintWriter out=res.getWriter();
    out.println("<html>");
    out.println("<body>");
    HttpSession hs=req.getSession();
    if(hs!=null);
    {
      hs.invalidate();
    }
    out.println("<h1>You are logout now...</h1>");
    out.println("</body>");
    out.println("</html>");
  }
}


INPUT::

Index.html::
<html><body>
<a href="download">Download the file</a>
</body></html>

Download.java::
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class download extends HttpServlet {
  public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException,   ServletException{
    PrintWriter out res.getWriter();
    String filename="sam.txt"; String filepath="D:\\":
    res.setHeader("Content-Disposition","attachment; filename="+filename);
    FileInputStream f=new FileInputStream(filepath+filename);
    int i;
    while((i=f.read())!=-1){
      out.write(i):
    }
    f.close();
  }
}