Caroline Lima: Servlets and JSP

Servlets and JSP (JavaServer Pages) are both technologies used in Java web development to create dynamic web applications. They are part of the Java EE (Enterprise Edition) platform and are often used together to build web applications.

Servlets

1. Purpose

- Servlets are Java classes that handle HTTP requests and generate HTTP responses.

- They are the backbone of Java web applications and provide a way to interact with clients via the web.

2. Functionality

- Servlets are responsible for processing requests, as form submissions, user authentication, database operations, etc., and generating dynamic responses.

- They can handle various types of HTTP requests (GET, POST, PUT, DELETE, etc.) and perform business logic accordingly.

3. Lifecycle

- Servlets follow a lifecycle consisting of initialization, service, and destruction phases. Developers can override specific methods (such as "init()", "doGet()", "doPost()", "destroy()") to customize the behavior of the servlet.

4. Example

import javax.servlet.*;

import javax.servlet.http.*;

import java.io.*;

public class HelloWorldServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html");

PrintWriter out = response.getWriter();

out.println("<html><body>");

out.println("<h2>Hello World!</h2>");

out.println("</body></html>");

}

JSP (JavaServer Pages)

1. Purpose

- JSP is a technology used to create dynamic web pages by embedding Java code within HTML markup.

- It simplifies the development of web applications by allowing developers to write Java code directly within the HTML pages.

2. Functionality

- JSP pages are compiled into servlets by the web container (e.g., Tomcat) during runtime, allowing them to execute Java code and generate dynamic content.

- JSP pages often contain a mix of static HTML content and dynamic Java code enclosed within special tags ("<% %>", "<%= %>", "<%-- --%>", etc.).

3. Lifecycle

- JSPs follow a similar lifecycle to servlets, but they are converted into servlets before being executed.

- JSPs can have predefined lifecycle methods such as "jspInit()", "jspService()", and "jspDestroy()".

4. Example

<%@ page language="java" contentType="text/html; charset=UTF-8"

pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

</head>

<body>

<h2>Hello <%= request.getParameter("name") %>!</h2>

</body>

</html>

Integration

- Servlets and JSPs are often used together in Java web applications.

- Servlets handle the backend processing, such as database access and business logic.

- JSPs handle the presentation layer, generating HTML content dynamically based on the data processed by servlets.

Together, servlets and JSPs provide a powerful and flexible framework for building dynamic and interactive web applications in Java.

Caroline Lima

Servlets and JSP

Servlets

JSP (JavaServer Pages)

Integration

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