Java Language - 94 - JSP (JavaServer Pages)

Java Enterprise Edition (Java EE) – JSP (JavaServer Pages)

Introduction to JavaServer Pages (JSP)

JavaServer Pages (JSP) is a Java-based technology that simplifies the creation of dynamic, platform-independent web content. JSP allows developers to embed Java code within HTML pages, making it easier to generate dynamic web content and interact with data and databases. It is an essential component of the Java Enterprise Edition (Java EE) platform.

Key Concepts and Features

JSP offers a variety of features that facilitate web application development:

Java-Centric: JSP is Java-centric, enabling developers to use Java code within their web pages for dynamic content generation.
Integration: JSP seamlessly integrates with Java EE technologies like Servlets, Enterprise JavaBeans (EJB), and databases for comprehensive web applications.
Tag Libraries: JSP provides custom and standard tag libraries, such as JavaServer Pages Standard Tag Library (JSTL), for easier and cleaner code organization.
Platform Independence: JSP pages are platform-independent, ensuring that web applications work on different server environments.

JSP Example

Let’s explore a simple JSP example. In this example, we’ll create a JSP page that displays a “Hello, JSP!” message.


<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<!DOCTYPE html>
<html>
<head>
    <title>Simple JSP Example</title>
</head>
<body>
    <h1>Hello, JSP!</h1>
    <p>Today is: <%= new java.util.Date() %></p>
</body>
</html>

In this example, we use JSP scriptlets (<%= ... %>) to embed Java code within the HTML template. We also display the current date using java.util.Date.

JSP Directives

JSP pages can include directives that provide instructions to the JSP container. Common directives include:

<%@ page ... %>: Used to set page attributes, like language, content type, and error page.
<%@ include ... %>: Includes content from an external file during translation.
<%@ taglib ... %>: Defines a tag library for use within the JSP page.

JSP Standard Actions

JSP provides a set of standard actions that allow developers to perform various tasks, including looping, conditionals, and database access, without writing extensive Java code. Here are some common JSP standard actions:

: Creates or retrieves a JavaBean instance.
: Iterates over a collection and generates HTML content.
: Sets up a database connection.
: Includes the output of another JSP page.

JSP Expression Language (EL)

JSP Expression Language (EL) simplifies the integration of dynamic content within JSP pages. It provides an easy way to access and display data from Java objects, collections, or request parameters. Here’s an example of EL usage:


<p>The total price is: <%= totalAmount * 0.9 %></p>
<p>The total price using EL is: ${totalAmount * 0.9}</p>

The expression ${totalAmount * 0.9} calculates the total price using EL, making the code cleaner and more readable.

JSP in a Web Application

In a Java EE web application, JSP pages are typically organized in a structured manner within the WEB-INF directory. JSP pages are responsible for generating dynamic content, while Servlets often handle request processing and business logic.

Conclusion

JavaServer Pages (JSP) is a powerful technology for building dynamic web applications within the Java EE platform. With its Java-centric approach, tag libraries, and easy integration with other Java EE components, JSP simplifies web application development while maintaining platform independence.

Java Language – 94 – JSP (JavaServer Pages)