JSP Custom Tag Working Example

To write your own jsp tag:
Create a HelloTag class that extends SimpleTagSupport class.
Example:

1. import javax.servlet.jsp.tagext.*;
2. import javax.servlet.jsp.*;
3. import java.io.*;
5. public class HelloTag extends SimpleTagSupport {
7. private String message;
9. public void setMessage(String msg) {
10. this.message = msg;
11. }
13. StringWriter sw = new StringWriter();
15. public void doTag()
16. throws JspException, IOException
17. {
18. if (message != null) {
19. /* Use message from attribute */
20. JspWriter out = getJspContext().getOut();
21. out.println( message );
22. }
23. else {
24.      System.out.println("msg is null");
25. /* use message from the body */
26. getJspBody().invoke(sw);
27. getJspContext().getOut().println(sw.toString());
28. }
29. }
31. }

Now create a  custom .tld file:
custom.tld:
-----------

1. <?xml version="1.0" encoding="UTF-8"?>
2. <!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN" "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
4. <taglib>
5. <tlib-version>1.0</tlib-version>
6. <jsp-version>2.0</jsp-version>
7. <short-name>Example TLD with Body</short-name>
8. <tag>
9. <name>Hello</name>
10. <tag-class>com.mohi.HelloTag</tag-class>
11. <body-content>scriptless</body-content>
12. <attribute>
13. <name>message</name>
14. </attribute>
15. </tag>
16. </taglib>

Usage:

Put the definitio on the top of your jsp page:

1. <%@ taglib prefix="ex" uri="../custom.tld"%>//be aware of the path you are using it's relative!

Using your tag in jsp page body:

1. <ex:Hello message="This is custom tag" />

Sample code:

Download JSPCustomTagExamplecode.zip
Unzip and run:
mvn clean install tomcat7:run
Browse to http://localhost:8080/SpringMVC/welcome