Basic concept of session- store some data of client temporarily which should be available until client destroy it.
Session management definition- It’s a mechanism used by web container to save state of client.
Session management includes-
1- session (interface)
2- cookies(class)
3- url rewriting
4- Hidden form field
1-Session-
step 1- creation of sessions-
(i)HttpSession ses=request.getsession();
-Returns existing session object else creates new session object.
(ii)HttpSession ses=request.getsession(true);
-Always returns existing session object.
(iii)HttpSession ses=request.getsession(false);
-Always creates new session object.
step 2- Initialization of servlet-
ses.setAttribute(key, value);
Note- Remove Attribute-
ses.removeAttribute(key);
step 3- Access of session-
ses.getAttribute(key);
4- Deletion of session-
ses.invalidate ();
Example 7- Wep app to create session at correct login, get session data from at profile page, and then logout to delete session.
Output-
Project Structure-
6 files-
1-index.html(inside WebContent)
2-Login.java(inside pacage=’ab’)
3-Profile.java(inside pacage=’ab’)
4-profile.html(inside WebContent)
5-Logout.java(inside pacage=’ab’)
6-web.xml(inside WEB-INF)
1-index.html
Insert title here email password <a href="profile">View Profile</a>
2-Login.java(servlet)
package ab;
import java.io.IOException;
import javax.servlet.*;
import javax.servlet.http.*;
public class Login extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String E1="mrjava@gmail.com";
String P1="java123";
String E2=request.getParameter("e");
String P2=request.getParameter("p");
if(E1.equals(E2)&amp;&amp;P1.equals(P2)){
HttpSession ses=request.getSession();
ses.setAttribute("mail", E2);
response.sendRedirect("profile");
}else{
response.sendRedirect("index.html");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
3-Profile.java(servlet)
package ab;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Profile extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
PrintWriter out=response.getWriter();
HttpSession ses=request.getSession();
String m=(String) ses.getAttribute("mail");
if(m!=null){
response.sendRedirect("profile.html");
}else{
RequestDispatcher rd=request.getRequestDispatcher("index.html");
rd.include(request, response);
out.println("You are not logged in.");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
4-profile.html
Insert title here Welcome user <a href="logout">Click here for logout</a>
5-Logout.java(servlet)
package ab;
import java.io.*;
import javax.servlet.http.*;
public class Logout extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
HttpSession ses=request.getSession();
ses.invalidate();
response.sendRedirect("index.html");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
6-web.xml
ExSession index.html index.htm index.jsp default.html default.htm default.jsp a ab.Login a /login b ab.Profile b /profile c ab.Logout c /logout
2- Cookies-
-cookie is a class.
-It stores textual data at client side.
-Less secure than session.
step 1- creation of cookie-
Cookie ck= new cookie(key, value);
step 2- send to the client side(browser)-
response. addCookie(ck);
step 3- access the cookie-
Cookie[] c= request.getCookies();
step 4- deletion of cookie-
ck.setAge(0);
response.addCookie(ck);
Example 8- Wep app to create cookie and add into browser at correct login, get cookies data from at profile page, and then logout to delete cookie.
output-
Project Structure-
6 files-
1-index.html(inside WebContent)
2-Login.java(inside pacage=’ab’)
3-Profile.java(inside pacage=’ab’)
4-profile.html(inside WebContent)
5-Logout.java(inside pacage=’ab’)
6-web.xml(inside WEB-INF)
1-index.html
Insert title here email password <a href="profile">View Profile</a>
2-Login.java(servlet)
package ab;
import java.io.IOException;
import javax.servlet.*;
import javax.servlet.http.*;
public class Login extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String E1="mrjava@gmail.com";
String P1="java123";
String E2=request.getParameter("e");
String P2=request.getParameter("p");
if(E1.equals(E2)&&P1.equals(P2)){
Cookie ck=new Cookie("mail", E2);
response.addCookie(ck);
response.sendRedirect("profile");
}else{
response.sendRedirect("index.html");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
3-Profile.java(servlet)
package ab;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Profile extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
PrintWriter out=response.getWriter();
Cookie[] ck2=request.getCookies();
System.out.println(ck2);
if(ck2!=null){
response.sendRedirect("profile.html");
}else{
RequestDispatcher rd=request.getRequestDispatcher("index.html");
rd.include(request, response);
out.println("You are not logged in.");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
4-profile.html
Insert title here Welcome user <a href="logout">Click here for logout</a>
5-Logout.java(servlet)
package ab;
import java.io.*;
import javax.servlet.http.*;
public class Logout extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Cookie[] ck2=request.getCookies();
for (Cookie c : ck2) {
c.setMaxAge(0);
response.addCookie(c);
}
response.sendRedirect("index.html");
}
6-web.xml
ExCookies index.html index.htm index.jsp default.html default.htm default.jsp a ab.Login a /login b ab.Profile b /profile c ab.Logout c /logout
3- Url Rewriting-
Step 1- add “?” At the end of url
Step 2 -add data in following format-
Attribute=value
Step 3- separate these attribute and value with “&” symbol
Example 9- Web app to add data with url and get it on next servlet.
output-
Project Structure-
3 files-
1-index.html(inside WebContent)
2-A.java(inside pacage=’ab’)
3-web.xml(inside WEB-INF)
1-index.html
Insert title here <a href="first?name=mr.Java&email=a@a.com">Click here</a>
2-A.java(servlet)
package ab;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class A extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String s1=request.getParameter("name");
String s2=request.getParameter("email");
PrintWriter out=response.getWriter();
out.println(s1);
out.println(s2);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
}
3-web.xml
ExUrlWr index.html index.htm index.jsp default.html default.htm default.jsp z ab.A z /first
4- hidden form field-
Step1- create input box with type=hidden
Step2- assign it’s value
Step3- get value of input box on next servlet.
Example 10- Wep app get data from hidden input box on next servlet.
output-
Project Structure-
3 files-
1-index.html(inside WebContent)
2-A.java(inside pacage=’ab’)
3-web.xml(inside WEB-INF)
1-index.html
Insert title here
2-A.java(servlet)
package ab;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class A extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String s1=request.getParameter("a");
String s2=request.getParameter("b");
String s3=request.getParameter("c");
PrintWriter out=response.getWriter();
out.println(s1);
out.println(s2);
out.println(s3);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
}
3-web.xml
ExHidden index.html index.htm index.jsp default.html default.htm default.jsp a ab.A a /first
