Java Reference
In-Depth Information
In this example you define the tag library to have a URI of
/djs
using the
taglib-uri
subele-
ment. In the second subelement you point the JSP container to the location of the tld, which is
in the directory
<SERVER_ROOT>/webapps/djs/WEB-INF/tlds/
and in a file named
taglib.tld
.
If you have chosen to deploy the tag handlers as a jar file then, assuming that your
tld
is
inside the jar, you will need to replace the contents of the
taglib-location
subelement with a
reference pointing directly to the jar file. A code snippet that demonstrates this is listed next:
<taglib>
<taglib-uri>/djs</taglib-uri>
<taglib-location> /WEB-INF/lib/djs.jar</taglib-location>
</taglib>
Adding the
taglib
Directive to Your JSP
Now that you have created the
tld
, deployed the tag handlers, and added the
tld
to your Web
application it is time to make the final connection by adding the
taglib
directive to the actual
JSP. The
taglib
directive has two purposes: It tells the JSP container the location of the tld
and it names the prefix that will link the tags to the named tld. It does this with two attributes.
The first attribute is the
uri
. It refers to a URI that uniquely identifies the tag library. This URI
references an attribute of a
taglib
entry of the Web application's
web.xml
file. The previous
example
taglib
entry is listed in the following code snippet:
<taglib>
<taglib-uri>/djs</taglib-uri>
<taglib-location>/WEB-INF/tlds/taglib.tld</taglib-location>
</taglib>
19
To reference the above Web application's
taglib
entry you would have to add the following
taglib
directive to your JSP:
<%@ taglib uri=”/djs” prefix=”djs” %>
Notice that the
uri
referenced in the JSP matches the
taglib-uri
referenced in the
web.xml
file. This tells the JSP container that this JSP references a tag library descriptor that is located
in the directory
<SERVER_ROOT>/webapps/djs/WEB-INF/tlds/
and the file containing the
taglib
descriptor is
taglib.tld
.
The second attribute defines the prefix of the tag library. This prefix is used to uniquely iden-
tify a given tag library from another tag library when parsing a JSP. In this example, the
prefix
attribute is
djs
; therefore a tag referencing the
/djs
tag library would always be begin
with
djs:
. The JSP container goes through the following steps when trying to resolve the loca-
tion of tag library descriptor:
