Iniciando na web com sistema de login

<%@page import="java.io.*"%>
<%@page import="java.util.ArrayList"%>

<%!class User implements Serializable {
		private String user;
		private String pass;
		private String ip;
		private String sid;

		public String getUser() {
			return user;
		}

		public String getPass() {
			return pass;
		}

		public String getIp() {
			return ip;
		}

		public String getSid() {
			return sid;
		}

		public void setUser(String u) {
			user = u;
		}

		public void setPass(String p) {
			pass = p;
		}

		public void setIp(String i) {
			ip = i;
		}

		public void setSid(String s) {
			sid = s;
		}

		public User(String u, String p) {
			user = u;
			pass = p;
			ip = null;
			sid = null;
		}

	}

	ArrayList<User> getListaUser() {
		ArrayList<User> listaUser = new ArrayList<User>();
		try {
			FileInputStream fis = new FileInputStream("pass");

			ObjectInputStream ois = new ObjectInputStream(fis);

			listaUser = (ArrayList) ois.readObject();

			ois.close();
		} catch (FileNotFoundException e) {
			System.out.println("Erro: " + e);
		} catch (IOException e) {
			System.out.println("Erro: " + e);
		} catch (ClassNotFoundException e) {
			System.out.println("Erro: " + e);
		}
		return listaUser;
	}

	void salvaListaUser(ArrayList<User> lista) {
		try {
			FileOutputStream fos = new FileOutputStream("pass");
			ObjectOutputStream oos = new ObjectOutputStream(fos);

			oos.writeObject(lista);

			oos.close();
		} catch (IOException e) {
			System.out.println(e);
		}
	}

	boolean login(String user, String pass) {
		boolean res = false;

		User u = new User(user, pass);
		res = getListaUser().contains(u);

		return res;
	}

	boolean loged(String sid, String ip) {
		boolean res = false;

		ArrayList<User> list = getListaUser();

		int t = list.size();

		for (int i = 0; i < t; i++) {
			if (list.get(i).getSid() == sid) {
				if (list.get(i).getIp() == ip) {
					res = true;
				}
			}
		}

		return res;
	}

	void registro(String user, String pass) {
		User u = new User(user, pass);
		ArrayList<User> lista = getListaUser();
		lista.add(u);

		salvaListaUser(lista);
	}

	void imprimeTudo() {
		User aux = null;
		ArrayList<User> auxLista = getListaUser();
		if (auxLista == null )
			System.out.println("erro, n encontrou auxLista");
		else {
		int s = auxLista.size();
			for (int i = 0; i < s; i++) {
				aux = auxLista.get(i);
				if ( aux != null ) {
					System.out.println(aux.getUser());
					System.out.println(" ");
					System.out.println(aux.getPass());
					System.out.println("<br>");
				}
			}
		}
	}%>

Cadastro
<form method="POST" action = "formCad.jsp"> 

<P>Usuario: <INPUT type="text" name="user">

<P>Senha: <INPUT type="text" name="pass">

<input type="submit" value="Submit">

</form>

<%@ include file="fuser.jsp" %>

<%
	String u = null;
	String p = null;
	u = request.getParameter("user");
	p = request.getParameter("pass");
	if ( u != null ) {
		if ( p != null ) {
			registro(u,p);
			out.println("Registrado... " + u + " " + p);
		}
	}
	else {
		out.println("nao registrado");
	}
%>

<%
	imprimeTudo();
%>