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javascript with jsp

Answer 1

A:

Java is evaluated on the server side, so in variable s you will always find

<script>document.writeln(jsvar)</script>

Javascript is evaluated on the opposide side, that is on the client's browser, so this is why your method does not work (I've fallen many time into this also ^^)

You can POST the form on the same jsp where this code resides and take the result from the POSTed data, to do that you'll use a scriptlet. If I remember correctly you could use

request.getParameter("PARAMETER_NAME")

So just add the name of the jsp where this code is to the action of the form and the above code to retrieve the selected value.

Alberto Zaccagni 2009-08-20 17:34:19

well actually the problem i am pushed to try this crap because of method="post" enctype="multipart/form-data" is not supporting any form element other than files.I am not sure why this problem occurs.

Harish 2009-08-20 17:43:11

Answer 2

+2 A:

my condition if(!(s.equals("Hello"))) fails

That is because this:

String s=(String)("<script>document.writeln(jsvar)</script>").toString();
out.println(s.equals("Hello"));

...is pretty much the same as writing:

out.println("this".equals("that"));

It will always be false.

Now what I am trying is to set the selected value as a session variable.

To set a variable in the session, you need to POST the form to the server (ignoring AJAX techniques, etc.). As I mentioned here, using multipart/form-data requires a MIME parser - the form below uses the default enctype.

This form will, when you select an option from the drop-down, post the form to the server. Every time the JSP is run, it uses a scriptlet <% ... %> tests to see if a "harish" parameter has been posted. If it has, it places it in the session. An expression <%= ... %> is used to display the current session value.

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
  pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"&gt;
<html>
<!-- header removed for clarity -->
<body>
<form id="test" name="test" action="test.jsp" method="post"><select
  name="harish" onchange="document.getElementById('test').submit();">
  <option value="select">select an option</option>
  <option value="1">1</option>
  <option value="2">2</option>
</select></form>
<%
  //see if a parameter was sent from page; "harish"==name attr on select
  String value = request.getParameter("harish");
  if (value != null) {
    //store it in session
    session.setAttribute("test", value);
  }
%>
<%="harish=" + session.getAttribute("test")%>
</body>
</html>

This assumes that the above page is test.jsp - that the page posts back to itself. If not, you'll need to move the scriptlet and the expression to test.jsp.

McDowell 2009-08-20 18:02:37

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