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Section 3. Step by step Custom Tag example (TagLib)

Using the XDoclet?s webdoclet task to create

Custom Tag TLDsClass level JavaDoc tags for

Custom Tags

Just like before, the mappings are quite natural. The first step is to define the jsp tag

using the jsp.tag and passing the name of the custom tag as follows:

* @jsp.tag name="BasicTag"

This code generates the following in the TLD file:

BasicTag

tomcatbook.customtag.BasicTag

...

Remember that XDoclet uses the JavaDoc API to get the full class name of the custom

tag handler. Next, you define any variables that you want available to the JSP pages

that use your custom tag. For this example, you defined three variables. One of the

variables can be used after the begin tag, one after the end tag only, and one only

inside the body, as shown here:

* @jsp.variable name given="currentIter"

*

class="java.lang.Integer" scope="NESTED"

* @jsp.variable name given="atBegin"

*

class="java.lang.Integer" scope="AT_BEGIN"

* @jsp.variable name given="atEnd"

*

class="java.lang.Integer" scope="AT_END"

A side benefit of XDoclet it that it keeps everything that makes of this Custom tag

together in one file. In addition, it is great for documenting what makes up this Custom

tag. Imagine not using XDoclet, you would have to go spelunking through a long TLD

file looking for the right entries (the

struts html.tld

file is 3000 lines long!) to see what

variables this tag defined.

This code generates the following in the TLD file within the basic tag definition:

currentIter

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Enhance J2EE component reuse with XDoclets