Help needed: clarifying the use of beans to pass data from database to JSP

Question

Hi everyone,
I am sure you all get fed up with being asked this question as I can see it is asked a lot when googled, but the answers given have not cleared things up for me.
Anyway, I have a JSP page that contains a text box, submit button and a select box of size 10. The user enters a search string and the form submits the data and reloads the same page. From the code you can see the Name property of the bean is set.
<jsp:useBean id="vtm" class="FinalYearProject.Types.VtmType" scope="page" />
<jsp:setProperty name="vtm" property="NM" value="${param.NM}" />I then need to be able to use that name to query a postgresql database. I have a JDBCConnector class with the method:
    public ResultSet searchTable(String NM ) throws SQLException {
        String[] names = NM.split(" ");
        NM = "";
        for(int i = 0; i < names.length; i++) {
            NM = names[i] + "%";
        return stat.executeQuery("SELECT * FROM vtm WHERE nm ILIKE '" + NM + "';");
    }This method however can be changed.
My question really is what is the best way for me to take the name, get the resultset and pass back the VtmType objects to the jsp so that I can populate my select box, and where should each part be handled i.e. the JSP page, the VtmType, the JDBCConnector.
I may be going about it completely the wrong way and using beans incorrectly, but I just cant seem to get my head around the problem.
Any help would be much appreciated,
Thanks.

Answer 1

Hi,
Thanks for the help, I actually found some literature about the JSP Model 2 and realised that was what I needed to do. I have now re-written everything and it has made my life a lot eaiser, typically this was before I checked back on this post though!
Anyway, I now have JSP pages requesting Servlets which create beans and call classes that access the database. The servlet then forwards the beans and where necessary a small of html to another JSP. Like you have suggested.
One problem I have now however, is that the user needs to be logged in to access some of the pages. An error page with the correct message is displayed to the user when it is processed via the servlet.
//Servlet detects an error
request.setAttribute("errorMsg", "1");
gotoPage("/loginError.jsp", request, response);
//JSP detects which errorMsg to display
<c:set var="errorMsg" value="${requestScope.errorMsg}" />However, when the user does not sign in and clicks a link which is blocked the JSP forwards directly to the error JSP.
//Tests to see if user is logged in
<c:if test="${empty user.username}">
    <jsp:forward page="/loginError.jsp">
        <jsp:param name="errorMsg" value="3" />
    </jsp:forward>
</c:if>The problem with this is that the only way I can see of checking the errorMsg type is with:
//JSP checks which errorMsg to display
<c:set var="errorMsg" value="${param.errorMsg}" />Which is different to how I determine the errorMsg from the Servlet. Is there a way of getting the errorMsg type that is the same for both actions?
Thanks.