What is JSP Custom Tag

by

A tag that references a JSP custom action.

In Advanced Java, a JSP (JavaServer Pages) custom tag refers to a custom action defined by a tag library and used in JSP pages to provide additional functionality beyond what is available with standard JSP tags. These custom tags are an essential part of Java EE (Enterprise Edition) development and are designed to simplify the coding of JSP pages.

Custom tags are created by Java developers or third-party libraries and can encapsulate complex Java logic, making it easier to reuse and maintain. There are two main types of custom tags in JSP:

  1. Custom Action Tags (or simply Custom Tags): These tags define custom actions that can be used in JSP pages. Custom actions are declared using XML-like syntax within the JSP page and can include attributes and body content. The actual implementation of these custom actions is typically provided in Java classes.Example of a custom tag declaration in a JSP page:
    jsp
    <mytags:customTag attribute1="value1" attribute2="value2">
    <!-- Body content of the custom tag -->
    Content goes here.
    </mytags:customTag>
  2. Tag Libraries (TLDs – Tag Library Descriptors): Tag libraries define the behavior of custom tags and are specified in Tag Library Descriptor files. These files contain information about the custom tags, including their names, attributes, and implementations.Example of a TLD file defining a custom tag:
    xml
    <taglib>
    <tlib-version>1.0</tlib-version>
    <jsp-version>2.0</jsp-version>
    <short-name>mytags</short-name>
    <uri>http://www.example.com/mytags</uri>    <tag>
    <name>customTag</name>
    <tag-class>com.example.CustomTagHandler</tag-class>
    <body-content>scriptless</body-content>
    <!– Other tag details and attributes –>
    </tag>

    <!– Other custom tags may be defined here –>
    </taglib>

In the example above, com.example.CustomTagHandler is the Java class that implements the behavior of the custom tag named customTag.

In summary, a JSP custom tag is a user-defined tag that extends the functionality of JSP by encapsulating Java logic in a reusable manner. Custom tags are declared in JSP pages and implemented in Java classes specified in Tag Library Descriptor files.