In this blog, we will discuss Directives in JSP. These directives provide directions and instructions to the container, telling it how to handle certain aspects of the JSP processing.

A JSP directive affects the overall structure of the servlet class. It usually has the following form −

<%@ directive attribute = "value" %>

Directives can have a number of attributes which you can list down as key-value pairs and separated by commas.

The blanks between the @ symbol and the directive name, and between the last attribute and the closing %>, are optional.

There are three types of directive tag −

S.No.	Directive & Description
1	<%@ page … %> Defines page-dependent attributes, such as scripting language, error page, and buffering requirements.
2	<%@ include … %> Includes a file during the translation phase.
3	<%@ taglib … %> Declares a tag library, containing custom actions, used in the page

JSP – The page Directive

The page directive is used to provide instructions to the container. These instructions pertain to the current JSP page. You may code page directives anywhere in your JSP page. By convention, page directives are coded at the top of the JSP page.

Following is the basic syntax of the page directive −

<%@ page attribute = "value" %>

You can write the XML equivalent of the above syntax as follows −

<jsp:directive.page attribute = "value" />

Attributes

Following table lists out the attributes associated with the page directive −

S.No.	Attribute & Purpose
1	buffer Specifies a buffering model for the output stream.
2	autoFlush Controls the behavior of the servlet output buffer.
3	contentType Defines the character encoding scheme.
4	errorPage Defines the URL of another JSP that reports on Java unchecked runtime exceptions.
5	isErrorPage Indicates if this JSP page is a URL specified by another JSP page’s errorPage attribute.
6	extends Specifies a superclass that the generated servlet must extend.
7	import Specifies a list of packages or classes for use in the JSP as the Java import statement does for Java classes.
8	info Defines a string that can be accessed with the servlet’s getServletInfo() method.
9	isThreadSafe Defines the threading model for the generated servlet.
10	language Defines the programming language used in the JSP page.
11	session Specifies whether or not the JSP page participates in HTTP sessions
12	isELIgnored Specifies whether or not the EL expression within the JSP page will be ignored.
13	isScriptingEnabled Determines if the scripting elements are allowed for use.

The include Directive

The include directive is used to include a file during the translation phase. This directive tells the container to merge the content of other external files with the current JSP during the translation phase. You may code the include directives anywhere in your JSP page.

The general usage form of this directive is as follows −

<%@ include file = "relative url" >

The filename in the include directive is actually a relative URL. If you just specify a filename with no associated path, the JSP compiler assumes that the file is in the same directory as your JSP.

You can write the XML equivalent of the above syntax as follows −

<jsp:directive.include file = "relative url" />

The taglib Directive

The JavaServer Pages API allow you to define custom JSP tags that look like HTML or XML tags and a tag library is a set of user-defined tags that implement custom behavior.

The taglib directive declares that your JSP page uses a set of custom tags, identifies the location of the library, and provides means for identifying the custom tags in your JSP page.

The taglib directive follows the syntax given below −

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

Here, the uri attribute value resolves to a location the container understands and the prefix attribute informs a container what bits of markup are custom actions.

You can write the XML equivalent of the above syntax as follows −

<jsp:directive.taglib uri = "uri" prefix = "prefixOfTag" />

So, this brings us to the end of blog. This Tecklearn ‘Directives in JSP’ blog helps you with commonly asked questions if you are looking out for a job in Java Programming. If you wish to learn JSP and build a career Java Programming domain, then check out our interactive, Java and JEE Training, that comes with 24*7 support to guide you throughout your learning period. Please find the link for course details:

https://www.tecklearn.com/course/java-and-jee-training/

Java and JEE Training

About the Course

Java and JEE Certification Training is designed by professionals as per the industrial requirements and demands. This training encompasses comprehensive knowledge on basic and advanced concepts of core Java & J2EE along with popular frameworks like Hibernate, Spring & SOA. In this course, you will gain expertise in concepts like Java Array, Java OOPs, Java Function, Java Loops, Java Collections, Java Thread, Java Servlet, and Web Services using industry use-cases and this will help you to become a certified Java expert.

Why Should you take Java and JEE Training?

Java developers are in great demand in the job market. With average pay going between $90,000/- to $120,000/- depending on your experience and the employers.
Used by more than 10 Million developers worldwide to develop applications for 15 Billion devices.
Java is one of the most popular programming languages in the software world. Rated #1 in TIOBE Popular programming languages index (15th Consecutive Year)

What you will Learn in this Course?

Introduction to Java

Java Fundamentals
Introduction to Java Basics
Features of Java
Various components of Java language
Benefits of Java over other programming languages
Key Benefits of Java

Installation and IDE’s for Java Programming Language

Installation of Java
Setting up of Eclipse IDE
Components of Java Program
Editors and IDEs used for Java Programming
Writing a Simple Java Program

Data Handling and Functions

Data types, Operations, Compilation process, Class files, Loops, Conditions
Using Loop Constructs
Arrays- Single Dimensional and Multi-Dimensional
Functions
Functions with Arguments

OOPS in Java: Concept of Object Orientation

Object Oriented Programming in Java
Implement classes and objects in Java
Create Class Constructors
Overload Constructors
Inheritance
Inherit Classes and create sub-classes
Implement abstract classes and methods
Use static keyword
Implement Interfaces and use it

Polymorphism, Packages and String Handling

Concept of Static and Run time Polymorphism
Function Overloading
String Handling –String Class
Java Packages

Exception Handling and Multi-Threading

Exception handling
Various Types of Exception Handling
Introduction to multi-threading in Java
Extending the thread class
Synchronizing the thread

File Handling in Java

Input Output Streams
io Package
File Handling in Java

Java Collections

Wrapper Classes and Inner Classes: Integer, Character, Boolean, Float etc
Applet Programs: How to write UI programs with Applet, Java.lang, Java.io, Java.util
Collections: ArrayList, Vector, HashSet, TreeSet, HashMap, HashTable

Java Database Connectivity (JDBC)

Introduction to SQL: Connect, Insert, Update, Delete, Select
Introduction to JDBC and Architecture of JDBC
Insert/Update/Delete/Select Operations using JDBC
Batch Processing Transaction
Management: Commit and Rollback

Java Enterprise Edition – Servlets

Introduction to J2EE
Client Server architecture
URL, Port Number, Request, Response
Need for servlets
Servlet fundamentals
Setting up a web project in Eclipse
Configuring and running the web app with servlets
GET and POST request in web application with demo
Servlet lifecycle
Servlets Continued
Session tracking and filter
Forward and include Servlet request dispatchers

Java Server Pages (JSP)

Fundamentals of Java Server Page
Writing a code using JSP
The architecture of JSP
JSP Continued
JSP elements: Scriptlets, expressions, declaration
JSP standard actions
JSP directives
Introduction to JavaBeans
ServletConfig and ServletContext
Servlet Chaining
Cookies Management
Session Management

Hibernate

Introduction to Hibernate
Introduction to ORM
ORM features
Hibernate as an ORM framework
Hibernate features
Setting up a project with Hibernate framework
Basic APIs needed to do CRUD operations with Hibernate
Hibernate Architecture

POJO (Plain Old Java Object)

POJO (Plain Old Java Object)
Persistent Objects
Lifecycle of Persistent Object

Spring

Introduction to Spring
Spring Fundamentals
Advanced Spring

Got a question for us? Please mention it in the comments section and we will get back to you.

306