A JSP Application to Display a Custom Tag

The following example code demonstrates how to develop a JSP Application to Display a Custom Tag.

Here’s an example of creating a custom tag in JSP.

Create a Java class for the custom tag handler.

import java.io.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;

public class HelloTag extends SimpleTagSupport {
   public void doTag() throws JspException, IOException {
      JspWriter out = getJspContext().getOut();
      out.println("Hello World!");
   }
}

2. Create a tag library descriptor (TLD) file.

<taglib>
   <tlib-version>1.0</tlib-version>
   <jsp-version>2.0</jsp-version>
   <short-name>Hello</short-name>
   <uri>http://example.com/tags/hello</uri>
   <tag>
      <name>hello</name>
      <tag-class>HelloTag</tag-class>
      <body-content>empty</body-content>
   </tag>
</taglib>

3. Reference the tag library in a JSP file.

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

<html>
   <head>
      <title>Hello World Tag</title>
   </head>
   <body>
      <hello:hello />
   </body>
</html>

In this code, the custom tag handler class HelloTag extends the SimpleTagSupport class, which provides a simple implementation of the Tag interface. The doTag() method is called when the custom tag is encountered in the JSP file. The method uses the JspWriter class to write “Hello World!” to the output. The TLD file hello.tld defines the custom tag and its attributes. The JSP file references the tag library using the taglib directive and uses the custom tag <hello:hello />.

Note: This code is just an example, and you should make changes to it according to your needs and the specifics of your project.

Further Reading