Introduction to Servlet and JSP
What is a Servlet?
A Servlet is a Java program that runs on a web server and handles requests and responses in a web application. Servlets are part of the Java EE (Enterprise Edition) specification and are used to extend the capabilities of a server by providing dynamic content.Key Features of Servlets:
- Platform Independence: Servlets are written in Java, making them platform-independent due to the Java Virtual Machine (JVM). - Efficient Handling of Requests: Servlets can handle multiple requests concurrently through multi-threading. - Integration with Java: Servlets can easily utilize Java libraries and frameworks, making them powerful for backend processing.Example of a Simple Servlet:
Here’s a simple example of a servlet that responds with a “Hello, World!” message:`java
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/hello") public class HelloWorldServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); response.getWriter().println("
Hello, World!
"); } }`What is JSP?
JavaServer Pages (JSP) is a technology that simplifies the creation of dynamic web content. JSP allows you to embed Java code directly into HTML pages, which makes it easier to write web applications.Key Features of JSP:
- Easy to Use: JSP is more user-friendly for designers who are familiar with HTML. It allows for the easy integration of Java code with HTML markup. - Automatic Compilation: JSP pages are automatically compiled into servlets by the server, which simplifies deployment. - Separation of Concerns: JSP encourages the separation of business logic from presentation, making it easier to maintain applications.Example of a Simple JSP Page:
Here’s a simple example of a JSP page that displays the current date:`jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
Current Date
The date today is: <%= new java.util.Date() %>
`