Home > Articles > Programming > Java

JSP Tag Libraries: The Basics

This chapter describes how to create and use custom tags utilizing the new SimpleTag API, which was introduced in version 2.4 of the servlet specification. As its name suggests, SimpleTag API is very easy to use in comparison to its predecessor, now known as the classic tag API.
This chapter is from the book

Topics in This Chapter

  • Identifying tag library components
  • Creating simple custom tags
  • Handling attributes in custom tags
  • Outputting tag bodies
  • Creating JSP-based custom tags with tag files

As discussed in Volume 1 (Section 11.2) of Core Servlets and JavaServer Pages, you have many options when it comes to generating dynamic content inside the JSP page. These options are as follows:

  • Scripting elements calling servlet code directly
  • Scripting elements calling servlet code indirectly (by means of utility classes)
  • Beans
  • Servlet/JSP combo (MVC)
  • MVC with JSP expression language
  • Custom tags

The options at the top of the list are much simpler to use and are just as legitimate as the options at the bottom of the list. However, industry has adopted a best practice to avoid placing Java code inside the JSP page. This best practice stems from it being much harder to debug and maintain Java code inside the JSP page. In addition, JSP pages should concentrate only on the presentation logic. Introducing Java code into the JSP page tends to divert its purpose and, inevitably, business logic starts to creep in. To enforce this best practice, version 2.4 of the servlet specification went so far as to provide a way to disable any type of JSP scripting for a group of JSP pages. We discuss how to disable scripting in Section 2.14 (Configuring JSP Pages).

That said, there are cases where the presentation logic itself is quite complex and using the non-Java code options in the JSP page to express that logic becomes either too clunky and unreadable or, sometimes, just impossible to achieve. This is where logic through the familiar HTML-like structures.

This chapter discusses how to create and use custom tags utilizing the new SimpleTag API, which was introduced in version 2.4 of the servlet specification. As its name suggests, SimpleTag API is very easy to use in comparison to its predecessor, now known as the classic tag API.

Although the SimpleTag API completely replaces the classic tag API, you should keep in mind that it works only in containers compliant with servlet specification 2.4 and above. Because there are still a lot of applications running on servlet 2.3-compliant containers, you should consider avoiding the SimpleTag API if you are not sure what type of container your code will end up on.

7.1 Tag Library Components

To use custom JSP tags, you need to define three separate components:

  • The tag handler class that defines the tag's behavior
  • The TLD file that maps the XML element names to the tag implementations
  • The JSP file that uses the tag library

The rest of this section gives an overview of each of these components, and the following sections give details on how to build these components for various styles of tags. Most people find that the first tag they write is the hardest—the difficulty being in knowing where each component should go, not in writing the components. So, we suggest that you start by just downloading the simplest of the examples of this chapter from http://volume2.coreservlets.com/ and getting those examples to work on your machine. After that, you can move on and try creating some of your own tags.

The Tag Handler Class

When defining a new tag, your first task is to define a Java class that tells the system what to do when it sees the tag. This class must implement the SimpleTag interface. In practice, you extend SimpleTagSupport, which implements the SimpleTag interface and supplies standard implementations for some of its methods. Both the SimpleTag interface and the SimpleTagSupport class reside in the javax.servlet.jsp.tagext package.

The very first action the container takes after loading the tag handler class is instantiating it with its no-arg constructor. This means that every tag handler must have a no-arg constructor or its instantiation will fail. Remember that the Java compiler provides one for you automatically unless you define a constructor with arguments. In that case, be sure to define a no-arg constructor yourself.

The code that does the actual work of the tag goes inside the doTag method. Usually, this code outputs content to the JSP page by invoking the print method of the JspWriter class. To obtain an instance of the JstWriter class you call getJspContext().getOut() inside the doTag method. The doTag method is called at request time. It's important to note that, unlike the classic tag model, the SimpleTag model never reuses tag handler instances. In fact, a new instance of the tag handler class is created for every tag occurrence on the page. This alleviates worries about race conditions and cached values even if you use instance variables in the tag handler class.

You place the compiled tag handler in the same location you would place a regular servlet, inside the WEB-INF/classes directory, keeping the package structure intact. For example, if your tag handler class belongs to the mytags package and its class name is MyTag, you would place the MyTag.class file inside the WEB-INF/classes/mytags/ directory.

Listing 7.1 shows an example of a tag handler class.

Listing 7.1. Example Tag Handler Class

package somepackage;

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

public class ExampleTag extends SimpleTagSupport {
  public void doTag() throws JspException, IOException {
    JspWriter out = getJspContext().getOut();
    out.print("<b>Hello World!</b>");

The Tag Library Descriptor File

Once you have defined a tag handler, your next task is to identify this class to the server and to associate it with a particular XML tag name. This task is accomplished by means of a TLD file in XML format. This file contains some fixed information (e.g., XML Schema instance declaration), an arbitrary short name for your library, a short description, and a series of tag descriptions. Listing 7.2 shows an example TLD file.

Listing 7.2. Example Tag Library Descriptor File

<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
    <description>Example tag</description>

We describe the details of the contents of the TLD file in later sections. For now, just note that the tag element through the following subelements in their required order defines the custom tag.

  • description. This optional element allows the tag developer to document the purpose of the custom tag.
  • name. This required element defines the name of the tag as it will be referred to by the JSP page (really tag suffix, as will be seen shortly).
  • tag-class. This required element identifies the fully qualified name of the implementing tag handler class.
  • body-content. This required element tells the container how to treat the content between the beginning and ending occurrence of the tag, if any. The value that appears here can be either empty, scriptless, tagdependent, or JSP.

    The value of empty means that no content is allowed to appear in the body of the tag. This would mean that the declared tag can only appear in the form:




    (without any spaces between the opening and closing tags). Placing any content inside the tag body would generate a page translation error.

The value of scriptless means that the tag body is allowed to have JSP content as long as it doesn't contain any scripting elements like <% ... %> or <%= ... %>. If present, the body of the tag would be processed just like any other JSP content.

The value of tagdependent means that the tag is allowed to have any type of content as its body. However, this content is not processed at all and completely ignored. It is up to the developer of the tag handler to get access to that content and do something with it. For example, if you wanted to develop a tag that would allow the JSP page developer to execute an SQL statement, providing the SQL in the body of the tag, you would use tagdependent as the value of the body-content element.

Finally, the value of JSP is provided for backward compatibility with the classic custom tag model. It is not a legal value when used with the SimpleTag API.

Note that there is no legal way of allowing any scripting elements to appear as the tag body under the new SimpleTag API model.

The TLD file must be placed inside the WEB-INF directory or any subdirectory thereof.

We suggest that you don't try to retype the TLD every time you start a new tag library, but start with a template. You can download such a template from http://volume2.coreservlets.com/.

The JSP File

Once you have a tag handler implementation and a TLD, you are ready to write a JSP file that makes use of the tag. Listing 7.3 gives an example. Somewhere in the JSP page you need to place the taglib directive. This directive has the following form:

<%@ taglib uri="..." prefix="..." %>

The required uri attribute can be either an absolute or relative URL referring to a TLD file like the one shown in Listing 7.2. For now, we will use a simple URL relative to the Web application's root directory. This makes it easy to refer to the same TLD file from multiple JSP pages in different directories. Remember that the TLD file must be placed somewhere inside the WEB-INF directory. Because this URL will be resolved on the server and not the client, it is allowed to refer to the WEB-INF directory, which is always protected from direct client access.

The required prefix attribute specifies a prefix to use in front of any tag name defined in the TLD of this taglib declaration. For example, if the TLD file defines a tag named tag1 and the prefix attribute has a value of test, the JSP page would need to refer to the tag as test:tag1. This tag could be used in either of the following two ways, depending on whether it is defined to be a container that makes use of the tag body:

<test:tag1>Arbitrary JSP</test:tag1>

or just

<test:tag1 />

Listing 7.3. Example JSP File

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<TITLE>Example JSP page</TITLE>
<%@ taglib uri="/WEB-INF/tlds/example.tld"
             prefix="test" %>

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020