Scriplets, that is, code in JSPs inside <% %>, is generally considered a Bad Thing(tm) because it's too easy for business logic to sneak into the presentation.
Now, there is I think room for debate about how far to push that idea. Some people think that a JSP should be absolutely nothing more than a template for display, so you should wind up with nothing but things like <$=someVar%>, or more "correctly", something like <bean:write name="myBean" property="myVar" />.
However, where there is room for debate is whether using any sort of logic whatsoever in a JSP is bad or not. Taking the "JSP as a template only" idea to it's fullest extent seems to me to imply that logic in ANY form is to be avoided, and should not be done in a JSP, whether it's using taglibs or not to do it (i.e., <logic:equal/> shouldn't even be used because it's logic). I think this is too extreme and limits the types of applications you can do... try doing the kinds of apps I do for a living for example, which are webapps that look, feel and work like fat clients, and you'll be hard-pressed to pull off the kinds of things I do without some level of logic in JSPs.
That being said, good design dictates that you need to be careful what gets put in your JSPs, whether you use custom tags or not (I'm not a fan of custom tags myself in most cases). Business logic does NOT belong in JSPs, and indeed anything other than trivial bits of code probably shouldn't be there either.
I'm not entirely sure what the code you posted is doing, but my gut feeling is that it's too much for a JSP. I do things like this all the time;
<%
boolean altRow = false;
String rowStyle = "";
for (Iterator it = form.getTOAList().iterator(); it.hasNext(); ) {
if (altRow) {
rowStyle = "cssListboxAltRow";
altRow = false;
} else {
rowStyle = "";
altRow = true;
}
HashMap nextItem = (HashMap)it.next();
BigDecimal toaID = (BigDecimal)nextItem.get("toaID");
String status = (String)nextItem.get("status");
%>
<tr height="24" class="<%=rowStyle%>">
<td><%=status%></td>
<td><%=toaID%></td>
</tr>
<%
}
%>...and some will say that's way too much... let's skip the "this should be a custom tag!" argument for the time being... This kind of code I see no problem with being in a JSP. It's strictly presentation-oriented, and isn't extensive.
That being said, NOW we can get to the "this shouldn't be there at all" argument... it is a perfectly reasonable argument. In an environment where you have page authors and Java coders, you don't want your page authors to have to see code like that. In fact, in the "perfect" environment where it's split exactly right, they wouldn't even know what this code meant. But, if you had a custom tag that encapsulated that functionality, they could just put <showTOAList/> and be done with it. That's the argument for taglibs (the main one anyway).
However, you have to ask yourself what kind of environment your in... I dare say most environments are NOT set up that way... maybe they should be, but I don't think the majority are... most places, your page authors are your Java coders are your database developers are your business analysts, etc. In that case, I think the argument doesn't carry as much weight.
Eh, I guess I'm off on a bit of a tangent. Most people will tell you that code in JSPs is to be avoided, and I'm not going out of my way to debate that. But, I think it's fair to say that if you do have code in JSPs, it should be (a) trivial and (b) strictly presentation-related. Breaking THOSE rules, which by extension breaks the higher rules, is to be avoided at all costs. Just my opinions.
-- Frank W. Zammetti Founder and Chief Software Architect Omnytex Technologies http://www.omnytex.com
Dola Woolfe wrote:
I just read this thread and didn't quite understand it. If it means what it seems to mean on the surface, I'm doing everything wrong.
Schematically, my typical JSP page looks like the following (basically 100% code). Is this what Craig is advising against?
<%@ page errorPage="ErrorPage.jsp" import="html.*"%> <[EMAIL PROTECTED] file="InitializePage.jsp"%> <% Table table = new Table() .pAddH("#").pAddH("Action").pLN() .pAddC("1").pAddL(new Anchor("HelloPage.jsp", "Say hello to my friend.")).pLN() .pAddC("2").pAddL(new Anchor("GoodByePage.jsp", "Say good bye to my friend")).pLN() ;
MyTemplate template = new MyTemplate ("Main Actions", table); Page pAgE = new Page(new MyHead("Data Tools"), new Body(template)); %>
<%= pAgE %>
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