JSP problem

Factual Questions
1

Is it illegal to have more than one jsp expression within a custom tag attribute? I have a case sort of like this:

<myTags:tag1 attr1="<%= val1 %>" attr2=“blahblah<%= attr2 %>foobar<%= attr3 %>” />

which renders as

… blahblah<%= attr2 %>foobar<%= attr3 %> …

I solved the problem by doing this instead

<myTags:tag1 attr1="<%= val1 %>" attr2="<%= “blahblah” + attr2 + “foobar” + attr3 %>" />

But I don’t know why that one works.

Any ideas?

Thanks,
Rob