How do I create a HelloWorld Servlet?

By Wayan in Servlet 0 Comment

Servlet is a Java solution for creating a dynamic web application, it can be compared with the old CGI technology. Using Servlet we can create a web application that can display information from a database, receive information from a web form to be stored in the application database.

This example shows the very basic of servlet, it returns a hello world html document for the browser. At the very minimum a servlet will have a doPost() and doGet() method which handles the HTTP POST and GET request.

package org.kodejava.servlet;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(name = "HelloWorldServlet", urlPatterns = {"/hello", "/helloworld"})
public class HelloWorld extends HttpServlet {

    public HelloWorld() {
        super();
    }

    protected void doGet(HttpServletRequest req, HttpServletResponse res)
            throws IOException {
        doPost(req, res);
    }

    protected void doPost(HttpServletRequest req, HttpServletResponse res)
            throws IOException {
        res.setContentType("text/html");

        PrintWriter writer = res.getWriter();
        writer.println("<html>");
        writer.println("<head><title>Hello World Servlet</title></head>");
        writer.println("<body>Hello World! How are you doing?</body>");
        writer.println("</html>");
        writer.close();
    }
}

When the servlet is deployed to the container we can access it from an url in a form of http://localhost:8080/app-name/helloworld.

Maven dependencies

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>4.0.1</version>
</dependency>

Maven Central

Wayan
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