CODEWITHSUNDEEP
javajavascriptjspservletsprompt
Stanley Mungai
Stanley Mungai

Reputation: 4150

Message Prompt Using JSP and Servlet Java

I am trying to implement an alert prompt using Javascript and JSP at Login but I cannot seen to Succeed. So far all that I have is an error Message Which I would like to come as a prompt. Please Help. This is what I have:

Servlet Side: 

String userValidate = logindao.authenticateUser(loginbean);
        if(userValidate.equals("SUCCESS")){
            request.setAttribute("userName", userName);
            request.getRequestDispatcher("/Home.jsp").forward(request, response);
        }else{
            request.setAttribute("errMessage", userValidate);
            request.getRequestDispatcher("/Login.jsp").forward(request, response);
        }

My JSP side :

<td><%=(request.getAttribute("errMessage") == null)
                                    ? ""
                                    : request.getAttribute("errMessage")%></td>

My DAO:

public class LoginDao {
    public String authenticateUser(LoginBean loginbean){
        String userName = loginbean.getUserName();
        String password = loginbean.getPassword();

        Connection conn = null;
        String userNameDB = "";
        String passwordDB = "";
        DBConnection db = new DBConnection();
        try{
            conn = db.getDbConnection();
            Statement st = conn.createStatement();
            ResultSet rs = st.executeQuery("SELECT USER_NAME, P_WORD, WORK_CLASS FROM USER_LOGIN "
                    + "where USER_NAME = '" + userName + "'");

            while(rs.next()){
                userNameDB = rs.getString("USER_NAME");
                passwordDB = rs.getString("P_WORD");
            }
            if(userName.equalsIgnoreCase(userNameDB)&& password.equalsIgnoreCase(passwordDB)){
                return "SUCCESS";
            }
            if(userName.equals("") || password.equals("")){
                return "Username or Password is blank";
            }
        }catch(Exception asd){
            System.out.println(asd);
        }
        return "invalid user credentials";
    }
}

If the cerdentials are wrong Alll I get is an error message Printed on the Page.How Can I have this as a Prompt Instead?

Upvotes: 0

Views: 3354

Answers (1)

Ravi K Thapliyal
Ravi K Thapliyal

Reputation: 51711

In your JSP add the following

<c:if test="${not empty errMessage}">
    <script>alert("${errMessage}");</script>
</c:if>

I've used EL as the use of scriptlets in JSP is deprecated. The ${attr} syntax simply pulls the value of an attribute named attr as test from either page, request, session or application scope in that order.

EDIT : (debug as)

<p>errMessage is: '<%= request.getAttribute("errMessage") %>'</p>
<c:if test="${not empty errMessage}">
    <script>alert("${errMessage}");</script>
</c:if>
<% request.setAttribute("errMessage", "forced error message"); %>
<c:if test="${not empty errMessage}">
    <script>alert("${errMessage}");</script>
</c:if>

Upvotes: 2

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