What is a servlet and what is it for?

  Servlets are Java classes, developed according to a well-defined structure that, when installed and configured on a Server that implements a Servlet Container, can handle requests received from Web clients such as Browsers (Internet Explorer® and Mozilla Firefox ®).

     

Upon receiving a request, a Servlet can capture the parameters of this request, perform any processing inherent in a Java class, and return an HTML page. - Withdrawn from Devmedia .

They are basically software modules that run on a web server to service client application requests and provide them with some kind of service.

That is, when you receive your request in the view, you need to receive this request, process it in some way, and send a response. Servlet receives your request, processes or sends it to someone else to process, and then returns the response to where you need it.

Servlet is a java class for working with web development although it is not specially designed for this.

In this class, requests are handled, two important members are request (input normally) and response (output).

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;

public class Teste extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public Teste() {
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

Servlet is a technology that the Java platform provides to web developers as a simple and consistent mechanism to extend the functionality of a web server and to access existing business systems. Servlets Java is what makes many web applications possible, they are responsible for generating the pages dynamically according to the user's request. In short, the goal is to receive HTTP calls, process them, and return a response to the client.

You can read a great explanation here .

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