Applet, Servlet, and JSP in Java

What is Applet?

An Applet is a small Java program that runs inside a web browser or an applet viewer. It was mainly used to create interactive web applications but is now obsolete because modern browsers no longer support it.

Features

• Runs on the client side.
• Extends the Applet class.
• No main() method.
• Uses lifecycle methods like init(), start(), stop(), and destroy().

Note: Applets are no longer used in modern Java web development.

What is Servlet?

A Servlet is a server-side Java program that handles client requests and generates dynamic web content. It runs inside a web server such as Apache Tomcat.

Features

• Runs on the server.
• Handles HTTP requests and responses.
• Improves performance by using multithreading.
• Extends HttpServlet.

Servlet Lifecycle

1. init() – Initializes the servlet.
2. service() – Processes client requests.
3. destroy() – Cleans up resources before removal.

Advantages

• Fast and efficient.
• Platform-independent.
• Secure and scalable.
• Supports session management.

What is JSP (JavaServer Pages)?

JSP (JavaServer Pages) is a server-side technology used to create dynamic web pages by embedding Java code inside HTML.

Features

• Simplifies web page development.
• Automatically converted into a servlet by the server.
• Supports HTML, CSS, JavaScript, and Java.
• Ideal for displaying dynamic data.

JSP Lifecycle

1. Translation into a Servlet.
2. Compilation.
3. Initialization (jspInit()).
4. Request Processing (_jspService()).
5. Destruction (jspDestroy()).

Advantages

• Easy to write and maintain.
• Reduces Java code in web pages.
• Reusable using JSP tags and Expression Language (EL).
• Better separation of presentation and business logic.