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<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">  <head>    <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />    <meta http-equiv="Content-Style-Type" content="text/css" />    <title>Custom Tags in JSP Pages</title>    <link rel="StyleSheet" href="document.css" type="text/css" media="all" />    <link rel="StyleSheet" href="catalog.css" type="text/css" media="all" />    <link rel="Table of Contents" href="J2EETutorialTOC.html" />    <link rel="Previous" href="JSTL9.html" />    <link rel="Next" href="JSPTags2.html" />    <link rel="Index" href="J2EETutorialIX.html" />  </head>  <body>    <table width="550" summary="layout" id="SummaryNotReq1">      <tr>	<td align="left" valign="center">	<font size="-1">	<a href="http://java.sun.com/j2ee/1.4/download.html#tutorial" target="_blank">Download</a>	<br>	<a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/faq.html" target="_blank">FAQ</a>	<br>	<a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/history.html" target="_blank">History</a>	</td>        <td align="center" valign="center"><a accesskey="p" href="JSTL9.html"><img id="LongDescNotReq1" src="images/PrevArrow.gif" width="26" height="26" border="0" alt="Prev" /></a><a accesskey="c" href="J2EETutorialFront.html"><img id="LongDescNotReq1" src="images/UpArrow.gif" width="26" height="26" border="0" alt="Home" /></a><a accesskey="n" href="JSPTags2.html"><img id="LongDescNotReq3" src="images/NextArrow.gif" width="26" height="26" border="0" alt="Next" /></a><a accesskey="i" href="J2EETutorialIX.html"></a>        </td>	<td align="right" valign="center">	<font size="-1">	<a href="http://java.sun.com/j2ee/1.4/docs/api/index.html" target="_blank">API</a>	<br>	<a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/search.html" target="_blank">Search</a>	<br>	<a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/sendusmail.html" target="_blank">Feedback</a></font>	</font>	</td>      </tr>    </table>    <img src="images/blueline.gif" width="550" height="8" ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Divider">    <blockquote><a name="wp74644"> </a><h2 class="pTitle">Custom Tags in JSP Pages</h2><a name="wp89431"> </a><p class="pBody">The standard JSP tags simplify JSP page development and maintenance. JSP technology also provides a mechanism for encapsulating other types of dynamic functionality in <em class="cEmphasis">custom tags</em>, which are extensions to the JSP language. Some examples of tasks that can be performed by custom tags include operations on implicit objects, processing forms, accessing databases and other enterprise services such as e-mail and directories, and flow control. Custom tags increase productivity because they can be reused across more than one application.</p><a name="wp89432"> </a><p class="pBody">Custom tags are distributed in a <em class="cEmphasis">tag library</em>, which defines a set of related custom tags and contains the objects that implement the tags. The object that implements a custom tag is called a <em class="cEmphasis">tag handler</em>. JSP technology defines two types of tag handlers: simple and classic. Simple tag handlers can only be used for tags that do not use scripting elements in attribute values or the tag body. Classic tag handlers must be used if scripting elements are required. Simple tag handlers are covered in this chapter and classic tag handlers are discussed in Chapter&nbsp;<a  href="JSPAdvanced.html#wp65706">16</a>.</p><a name="wp89437"> </a><p class="pBody">You can write simple tag handlers with the JSP language or with the Java language. A <em class="cEmphasis">tag file</em> is a source file containing a reusable fragment of JSP code that is translated into a simple tag handler by the Web container. Tag files can be used to develop custom tags that are presentation-centric or that can take advantage of existing tag libraries, or by page authors who do not know Java. For occasions when the flexibility of the Java programming language is needed to define the tag, JSP technology provides a simple API for developing a tag handler in the Java programming language. </p><a name="wp89441"> </a><p class="pBody">This chapter assumes you are familiar with the material in Chapter&nbsp;<a  href="JSPIntro.html#wp65706">12</a>, especially the section <a  href="JSPIntro9.html#wp73314">Using Custom Tags</a>. For more information about tag libraries and for pointers to some freely-available libraries, see </p><div class="pPreformattedRelative"><pre class="pPreformattedRelative"><code class="cCode"><a  href="http://java.sun.com/products/jsp/taglibraries.html" target="_blank">http://java.sun.com/products/jsp/taglibraries.html</a></code><a name="wp89446"> </a></pre></div>    </blockquote>   <img src="images/blueline.gif" width="550" height="8" ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Divider">    <table width="550" summary="layout" id="SummaryNotReq1">      <tr>	<td align="left" valign="center">	<font size="-1">	<a href="http://java.sun.com/j2ee/1.4/download.html#tutorial" target="_blank">Download</a>	<br>	<a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/faq.html" target="_blank">FAQ</a>	<br>	<a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/history.html" target="_blank">History</a>	</td>        <td align="center" valign="center"><a accesskey="p" href="JSTL9.html"><img id="LongDescNotReq1" src="images/PrevArrow.gif" width="26" height="26" border="0" alt="Prev" /></a><a accesskey="c" href="J2EETutorialFront.html"><img id="LongDescNotReq1" src="images/UpArrow.gif" width="26" height="26" border="0" alt="Home" /></a><a accesskey="n" href="JSPTags2.html"><img id="LongDescNotReq3" src="images/NextArrow.gif" width="26" height="26" border="0" alt="Next" /></a><a accesskey="i" href="J2EETutorialIX.html"></a>        </td>	<td align="right" valign="center">	<font size="-1">	<a href="http://java.sun.com/j2ee/1.4/docs/api/index.html" target="_blank">API</a>	<br>	<a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/search.html" target="_blank">Search</a>	<br>	<a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/sendusmail.html" target="_blank">Feedback</a></font>	</font>	</td>      </tr>    </table>    <img src="images/blueline.gif" width="550" height="8" ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Divider"><p><font size="-1">All of the material in <em>The J2EE(TM) 1.4 Tutorial</em> is <a href="J2EETutorialFront2.html">copyright</a>-protected and may not be published in other workswithout express written permission from Sun Microsystems.</font>  </body></html>
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