Hello everyone, I would like to ask you some help in clarifying a few issues. But, before anything, some code is inbound first - it's a really simple login example I've constructed.
Container is Tomcat 5.5.27.
Let's assume correct username and pass combination is entered; questions are at the bottom.
LoginPage.jsp (entrypoint - view)
<%@ page language="java" contentType="text/html; charset=windows-1250" pageEncoding="windows-1250"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<link rel="stylesheet" type="text/css" href="mystyle.css" />
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Login Page</title>
</head>
<body>
<div id="page">
<div id="content_container">
<div id="content">
<form action="LoginServlet">
Username: <input type="text" name="username"><br>
Password: <input type="text" name="password"><br>
<input type="submit" value="Submit">
</form>
</div>
</div>
</div>
</body>
</html>
LoginServlet.java (controller)
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public LoginServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
UserBean user = new UserBean();
user.setUsername(request.getParameter("username"));
user.setPassword(request.getParameter("password"));
user = UserDAO.login(user);
if(user.isValid()){
HttpSession session = request.getSession();
session.setAttribute("currentSessionUser", user);
response.sendRedirect("userLogged.jsp");
} else {
response.sendRedirect("invalidLogin.jsp");
}
} catch (Exception e){
e.printStackTrace();
}
}
}
UserDAO.java ("service" class)
//snipped imports and such
public class UserDAO {
static Connection currConn = null;
static ResultSet rs = null;
public static UserBean login(UserBean userBean) {
Statement stmt = null;
String username = userBean.getUsername();
String password = userBean.getPassword();
String searchQuery = "SELECT * FROM pilots x WHERE x.email = '" + username + "' AND x.password = '" + password + "'";
System.out.println("Your user name is " + username);
System.out.println("Your password is " + password);
System.out.println("Query: " + searchQuery);
try {
currConn = ConnectionManager.getConnection();
stmt = currConn.createStatement();
rs = stmt.executeQuery(searchQuery);
boolean more = rs.next();
if (!more) {
System.out.println("Sorry, you are not a registered user! Please sign up first");
userBean.setValid(false);
} else {
String firstName = rs.getString("FIRST_NAME");
String lastName = rs.getString("LAST_NAME");
System.out.println("Welcome " + firstName);
userBean.setFirstName(firstName);
userBean.setLastName(lastName);
userBean.setValid(true);
}
} catch (Exception ex) {
System.out.println("Log In failed: An Exception has occurred! " + ex);
ex.printStackTrace();
} finally {
if(rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(currConn != null){
try {
currConn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
return userBean;
}
}
UserBean.java (model, a classic POJO/bean used as a DTO)
//...
public class UserBean {
private String username;
private String password;
private String firstName;
private String lastName;
private boolean valid;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public boolean isValid() {
return valid;
}
public void setValid(boolean valid) {
this.valid = valid;
}
}
userLogged.jsp (exitpoint - view) --never mind the div elements-
<%@ page language="java" contentType="text/html; charset=windows-1250" pageEncoding="windows-1250"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<link rel="stylesheet" type="text/css" href="mystyle.css" />
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Successful login!</title>
</head>
<body>
<div id="page">
<div id="content_container">
<div id="content">
<jsp:useBean id="currentSessionUser" class="examplePackage.UserBean" scope="application">
Welcome, <jsp:getProperty name="currentSessionUser" property="username"/> <br>
********<br>
Test 0 -> ${param.name}<br>
Test 1 -> ${paramValues.name[0]}<br>
Test 2 -> ${paramValues[name[0]]}<br>
Test 3 -> ${param["name"]}<br>
Test 4 -> ${param.username}<br>
Test 5 -> ${param["username"]}<br>
Test 6 -> ${sessionScope.currentSessionUser.username}<br>
*******<br>
Test 7 -> ${header.host}<br>
Test 8 -> ${header["host"]}<br>
Test 9 -> ${pageContext.request.method}<br>
</jsp:useBean>
</div>
</div>
</div>
</body>
</html>
Webpage output is as follows (c/p directly from FireFox):
Welcome, USER_X
********
Test 0 ->
Test 1 ->
Test 2 ->
Test 3 ->
Test 4 ->
Test 5 ->
Test 6 -> USER_X
*******
Test 7 -> localhost:8080
Test 8 -> localhost:8080
Test 9 -> GET
1) My first question is regarding the scope - which scope is actually applicable?? If you checkout userLogged.jsp, lines 13 and 22 (L13 and L22), you'll see my dilemma - if I use any other scope than "application" in L13, L14 returns null value. On the other hand, should I use applicationScope on L22, it returns null (as it darn well should, since I am setting a SESSION attribute, not a context attribute!). So, the question is - why should I use application scope on L13 anyway?? I'd expect nothing other than session scope, as can be seen from my controller.
2) The other question is regarding EL - why can't I fetch request parameters in Tests 0-5? Other stuff works fine (as can be seen from output), but I can't understand how to make these request parameters printed out as I inteded (via request EL implicit objects).
3) I am also curious as to why this won't work if I were to use it (L24 of userLogged.jsp, change attribute to property="*")?
Welcome, <jsp:getProperty name="currentSessionUser" property="*"/>
It returns null, and I've matched my domain object (UserBean) properties according to JavaBeans spec. I'd expect it would return ALL userBean properties that are matchable to input type field from LoginPage.jsp and are of correct type to use the feature (must be String or primitive).
Thank you very much in advance
With regards EK