Java Servlets

 Java Servlets are server-side Java programs that handle client requests and generate dynamic web content. Part of the Java EE (Jakarta EE) specification, Servlets are the foundation for many Java-based web applications, acting as a bridge between a client (usually a browser) and a server-side application.

What is a Servlet?

A Servlet is a Java class that extends the capabilities of servers hosting applications accessed by web clients. It runs within a Servlet container like Apache Tomcat, Jetty, or WildFly.

Servlets respond to requests—usually HTTP—and generate responses, typically in HTML, JSON, or XML format. They are part of the javax.servlet and javax.servlet.http packages.

Servlet Lifecycle

Servlets follow a specific lifecycle managed by the servlet container:

Initialization (init()) – Called once when the servlet is created.

Request handling (service()) – Called for each client request.

Destruction (destroy()) – Called when the servlet is taken out of service.

For HTTP-specific functionality, servlets often override doGet() and doPost() methods from HttpServlet.

Example:

public class HelloServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {

        response.setContentType("text/html");

        PrintWriter out = response.getWriter();

        out.println("<h1>Hello from Servlet!</h1>");

    }

}

This servlet responds to a GET request with an HTML message.

Web Deployment

Servlets are deployed through a web.xml configuration file or annotated using @WebServlet:

@WebServlet("/hello")

public class HelloServlet extends HttpServlet {

    // implementation

}

This annotation maps the servlet to a specific URL, allowing the web server to direct incoming requests appropriately.

Benefits of Servlets

Platform-independent – Runs on any server with a compatible container.

Efficient – Managed in memory, eliminating overhead of CGI scripts.

Scalable – Can handle multiple simultaneous client requests.

Extensible – Easily integrate with JSP, JDBC, and frameworks like Spring MVC.

Conclusion

Java Servlets are a core technology for building dynamic web applications in the Java ecosystem. While modern frameworks abstract much of their complexity, understanding servlets is essential for mastering Java web development. They provide the foundation upon which many powerful web platforms are built.

Learn: Java Fullstack Training In Hyderabad

Generics

File I/O and Serialization

Java 8 Features (Streams, Lambdas, Optional)

Java Packages and Access Modifiers

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