How do I create a basic servlet using the HttpServlet class?

To create a basic servlet using the HttpServlet class in Jakarta Servlet API, follow these steps:

Steps to Create a Basic Servlet:

Create a Java Class Extending HttpServlet:
- Your servlet class should extend the HttpServlet class provided in the Jakarta Servlet API.
Define Servlet Annotations or Configuration:
- Use the @WebServlet annotation to define the servlet and map it to a URL pattern. Alternatively, you can configure it in the web.xml file if annotations are not used.
Override doGet or doPost Methods:
- Override doGet for handling GET requests and doPost for POST requests (based on the type of request you expect).
Set the Content Type in Response:
- The response content type can be set using response.setContentType().
Write the Response to Output:
- Use a PrintWriter object received from response.getWriter() to write the response content.

Code Example:

Here’s a sample implementation for a basic servlet:

package org.kodejava.servlet;

import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;
import java.io.PrintWriter;

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

   @Override
   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
      response.setContentType("text/html");

      PrintWriter writer = response.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();
   }
}

Explanation of Code:

@WebServlet Annotation:
- name: Specifies the servlet name.
- urlPatterns: Maps the servlet to specific URL patterns (in this example, /hello).
doGet Method:
- Handles GET requests sent to /hello.
- Sets the content type for the response to text/html so that the client knows the returned content is HTML.
- Dynamically writes an HTML page to the response using the PrintWriter.
Response Lifecycle:
- Any request to http://<server>:<port>/hello is routed to the doGet method based on the @WebServlet mapping.

Deploying the Servlet in Jakarta EE:

Place your servlet class in the Java package structure under src/main/java.
Ensure your project is configured to use a Jakarta Servlet container like Apache Tomcat or Jakarta EE compatible application server.
Deploy the .war file or run directly if your IDE supports it.

To build the .war file you can follow in steps in this post: How to build WAR file for Jakarta EE Servlet Container?.

Maven dependencies

<dependency>
    <groupId>jakarta.servlet</groupId>
    <artifactId>jakarta.servlet-api</artifactId>
    <version>6.1.0</version>
    <scope>provided</scope>
</dependency>

Author
Recent Posts

Wayan

Founder at Kode Java

Hi, I'm a passionate programmer based on the beautiful island of Bali. I specialize in Java, with hands-on experience in Spring, Hibernate/JPA, and MySQL. I'm currently working on a project I care deeply about, and your support—big or small—helps fuel my work (and my coffee ☕️).

If you like what I’m building, consider buying me a cup of coffee. Thanks a lot!

Steps to Create a Basic Servlet:

Code Example:

Explanation of Code:

Deploying the Servlet in Jakarta EE:

Leave a ReplyCancel reply