Question

Here’s what I’ve got going on. I have one .jsp file. However, I have two forms with multiple inputs inside those forms.

What is the best way to detect that one form was submitted but not the other? Here’s an example: I have this form:

<form  name = "login" action="index.jsp" method="get">
Username: <input id="username" name="username" type="text"/><br/>
Password: <input id="password" name="password" type="password"/>
<input type="submit" Value="Login" ></input>
</form>

If that button is clicked, I’d like to run this code:

String username = request.getParameter("username");
String password = request.getParameter("password");
if((username!= null && !username.trim().equals("")) && (password != null && !username.trim().equals(""))) {
    DBentry DBentry=new DBentry();
    boolean flag = DBentry.isTaken(username);
    if(flag) {%><script type="text/javascript">alert("Login Successful!");</script><%
        }
    else { %><script type="text/javascript">alert("Unrecognized username.  Please register!");</script><% }
    }
else { %><script type="text/javascript">alert("Please enter both a username and password!");</script><% }

Further down I would have something exactly like it but submitting a different form.
Thanks!

Answer 1

Give the submit button an unique name. It becomes the request parameter name. This way you can just check if HttpServletRequest#getParameter() doesn’t return null.

E.g.

<input type="submit" name="login" Value="Login" />

...

<input type="submit" name="somethingelse" Value="Something else" />

with

if (request.getParameter("login") != null) {
    // Login form submitted.
}
else if (request.getParameter("somethingelse") != null) {
    // Something else submitted.
}

---

Unrelated to the concrete problem, business logic doesn’t belong in a JSP, but in a Servlet. I’d start working on that as well. This enables you to submit the forms to different URLs. Also, you should be using POST method for this, not GET method.