JSP STANDARD TAG LIBRARY

INTRODUCTIONThe latest version of JSTL is JSTL 1.1. Without any hesitation, JSTL is now extremely important in ensuring the success of the J2EE web application projects. JSTL is basically part of JSP 2.0 specification and requires Java Servlet 2.4 and higher to support its tags.

WHAT IS JSTL?JSTL stands for JSP Standard Tag Library.

JSTL has been standardized and is being one of the most important technologies in implementing J2EE Web Application.

The main objective of the JSTL is basically to simplify the Java codes within JSP (scriptlets) as well as to increase the level of reusability within our J2EE web application.

J2EE Web Applications (especially in the presentation layer JSP) are extremely complex and are very tough to be maintained. It is true that the new developer may take some time to understand all the underlying codes within J2EE Web Application This is where JSTL should help.

CONTINUEDHere is a simple JSTL flow concept; JSTL is compiled into a servlets (Java codes) before being displayed to JSP. Some classes of standard.jar are required to parse and translate these JSTL tags into servlets (Java codes). Lastly but not least, the servlet that has been compiled will be executed accordingly. There are many more advantages of using JSTL compared to scriptlets. Therefore, it is recommended to replace scriptlets with JSTL in the presentation layer (JSP). There are 5 major types of JSTL tags: JSTL Core tags, prefixed with c JSTL Format tags, prefixed with fmt JSTL Function tags, prefixed with fn JSTL Database tags, prefixed with sql JSTL XML tags, prefixed with x

CONTINUEDJSTL Core Tags Mainly used for replacement of scriptlet logical tags as well as basic URL handling tag such as catch, choose, if, forEach, param, when, redirect, import, url, etc. JSTL Format Tags Mainly used for displaying number and date time format. This could be used for internationalization support as well. Tags examples are setLocale, setTimeZone, setBundle, formatNumber, formatDate, etc.

JSTL Function Tags Very useful JSTL tags. Most are used in conjunction with JSTL core tags. These tags are designed for manipulating string.

JSTL Database Tags Tags are used to interact with database level. With database tags you could do transaction, update and query the database from your UI level. Personally, I do not prefer these tags. The MVC design pattern should always be retained. JSTL XML tags Similar to core tags, except xml tags will deal with xml stuffs like parsing xml documents, validating xml documents, output an xpath and etc.

Operators JSP Notation

> gt < Lt >= ge

WHY USE JSTL?Advantage of JSTL Scriptlets (Java codes within JSP) are complex and are extremely hard to be maintained. Unlike scriptlets, JSTL makes our JSP readable and maintainable. HTML programmer may find it hard to modify the JSP with the scriptlets as he or she may not have the Java programming knowledge. However, if we are using JSTL to replace our scriptlets, HTML programmer can easily understand on whats going on in the JSP as JSTL is in the form of XML tags similar to the normal HTML tags. JSTL has been standardized and is reusable tags. The name of each tag in JSTL is self-explanatory and is easy to understand.JSTL requires less code compared to scriptlets.

CONTINUEDScriptlets provide you with greater flexibility. As scriptlets is simply a Java codes, you can do anything that you want as you normally do with a Java programming. On the other hand, JSTL is a very specific and each tag has its own purposes.

Implementation of JSTL Functional Tags

JSTL Format Tags