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package examples.shop.web.servlet;
import java.io.IOException;
import javax.ejb.EJB;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import examples.shop.logic.Cart;
import examples.shop.logic.UserManager;
/**
* This is the very first servlet the client deals with. It's a Login
* authentication servlet and asks the user for his name and password,
* and pass it to the UserManager stateless session bean for verificatiion.
*
* If the user authenticates properly, a reference to a new Cart is saved
* in his HttpSession object, and the user can begin to add items to his
* cart and shop around.
*/
public class LoginServlet extends HttpServlet {
/** the user manager used to authenticate the user */
@EJB
UserManager userManager;
/** the user's cart object */
@EJB
Cart cart;
/**
* The servlet engine calls this method once to initialize a servlet
* instance.
*/
public void init(ServletConfig config) throws ServletException {
super.init(config);
try {
/*
* Get the initial context using the above startup params.
*/
Context ctx = new InitialContext();
userManager = (UserManager) ctx.lookup(UserManager.class
.getName());
cart = (Cart) ctx.lookup(Cart.class.getName());
} catch (Exception e) {
log(e);
throw new ServletException(e.toString());
}
}
/**
* The servlet engine calls this method when the user's desktop browser
* sends an HTTP request.
*/
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*
* Set up the user's HttpSession
*/
HttpSession session = request.getSession(true);
System.out.println(request.getAttributeNames().toString());
/*
* Retrieve the login name / password from the URL string.
*/
String loginName = request.getParameter("Login");
String password = request.getParameter("Password");
boolean isLogin = false;
/*
* If user has not tried to log in yet, present him with the login
* screen.
*/
if ((loginName == null) || (password == null)) {
writeForm(request, response, false);
return;
} else {
/*
* Otherwise, the user has been to this screen already, and has
* entered some information. Verify that information.
*/
try {
isLogin = userManager.validateUser(loginName, password);
} catch (Exception e) {
writeForm(request, response, true);
e.printStackTrace();
return;
}
/*
* If the passwords match, make a new Cart Session Bean, and add it
* to the user's HttpSession object. When the user navigates to
* other servlets, the other servlets can access the HttpSession to
* get the user's Cart.
*/
if (isLogin) {
try {
cart.setOwner(loginName);
cart.clear();
session.setAttribute("cart", cart);
/*
* Call the main page
*/
RequestDispatcher disp = this.getServletContext()
.getRequestDispatcher("/wsf.jsp");
disp.forward(request, response);
return;
} catch (Exception e) {
log(e);
throw new ServletException(e.toString());
}
} else
writeForm(request, response, true);
}
/*
* If there was no match, the user is not authenticated. Present another
* login screen to him, with an error message indicating that he is not
* authenticated.
*/
writeForm(request, response, true);
}
/**
* Writes the Login Screen (private use only)
*
* @param showError
* true means show an error b/c client was not authenticated last
* time.
*/
private void writeForm(HttpServletRequest request,
HttpServletResponse response, boolean showError)
throws ServletException, IOException {
/*
* Set a variable indicating whether or not we failed to log-in. The JSP
* will read this variable.
*/
request.setAttribute("loginFailed", new Boolean(showError));
/*
* Forward the request to the login JSP
*/
RequestDispatcher disp = this.getServletContext().getRequestDispatcher(
"/login.jsp");
disp.forward(request, response);
}
private void log(Exception e) {
e.printStackTrace();
}
public String getServletInfo() {
return "The Login servlet verifies a user.";
}
}
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