The Java EE 5 Tutorial (PDF) - Oracle Software Downloads

Programming SimpleTag Handlers
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${departmentName}
Tag Handler
The collection is set in the tag handler by means of the group attribute. The tag handler retrieves
an element from the group and passes the element back to the page in the EL variable whose
name is determined by the var attribute. The variable is accessed in the calling page using the
JSP expression language. After the variable is set, the tag body is evaluated with the invoke
method.
public void doTag() throws JspException, IOException {
if (iterator == null)
return;
while (iterator.hasNext()) {
getJspContext().setAttribute(var, iterator.next());
getJspBody().invoke(null);
}
}
public void setVar(String var) {
this.var = var;
}
public void setGroup(Collection group) {
this.group = group;
if(group.size() > 0)
iterator = group.iterator();
}
ATemplateTag Library
A template provides a way to separate the common elements that are part of each screen from
the elements that change with each screen of an application. Putting all the common elements
together into one file makes it easier to maintain and enforce a consistent look and feel in all the
screens. It also makes development of individual screens easier because the designer can focus
on portions of a screen that are specific to that screen while the template takes care of the
common portions.
The Java EE 5Tutorial • June 2010