Creating Custom Tags in JSP - Programmingempire

Creating custom tags in JSP (JavaServer Pages) involves several steps. The following section gives a basic overview of the steps involved.

Steps for Creating Custom Tags in JSP

Define the tag handler class. Basically, this class processes the custom tag. It extends the javax.servlet.jsp.tagext.TagSupport class and overrides its methods to define the behavior of the tag. Also, the class should be placed in a Java package and compiled into a Java class file.
Define the tag library descriptor. It is an XML file that describes the custom tag and its behavior. It defines the tag name, tag class, and attributes, among other things. Place it in the WEB-INF directory of the web application.
Declare the tag library in the JSP. The JSP page that uses the tag must declare the tag library using the taglib directive. This directive specifies the location of the descriptor and assigns a prefix to the tag library.
Use the tag in JSP. Once the tag library is declared, you can use it in the JSP by specifying its name and any attributes it requires.

Example of Creating a Custom Tag

The following example demonstrates the above steps.

At first, define the tag handler class.

package com.example.tags;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
public class HelloWorldTag extends TagSupport {
  public int doStartTag() throws JspException {
    try {
      pageContext.getOut().println("Hello World!");
    } catch (Exception e) {
      throw new JspException(e.getMessage());
    }
    return SKIP_BODY;
  }
}

In this example, the HelloWorldTag class extends the TagSupport class and overrides its doStartTag() method to print “Hello World!” to the output stream of the JSP page.

2. After that, define the tag library descriptor. Also, Create a file named taglib.xml in the WEB-INF directory with the following content.

<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
        version="2.0">
  <tlib-version>1.0</tlib-version>
  <short-name>example</short-name>
  <uri>http://example.com/tags</uri>
  <tag>
    <name>hello</name>
    <tag-class>com.example.tags.HelloWorldTag</tag-class>
  </tag>
</taglib>

In this example, the tag element defines the custom tag named hello and specifies its tag class as com.example.tags.HelloWorldTag.

3. Next, declare the tag library in the JSP. For this purpose, add the following directive at the top of your JSP page to declare the tag library.

<%@ taglib uri="http://example.com/tags" prefix="ex" %>

4. Once, we create the tag, we can use it in the JSP. So, add the following tag to your JSP page to use the custom tag.

<ex:hello/>

When the JSP page is processed, the custom tag will be executed, and “Hello World!” will be printed to the output stream.

This is a basic example of creating a custom tag in JSP. The approach you choose will depend on the specific requirements of your application.

Steps for Creating Custom Tags in JSP

Example of Creating a Custom Tag

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