Servlet Roadmap

[Lomanu4]

Here’s a complete Servlet Roadmap — perfect for understanding how to work with Java Servlets for web development, especially if you're aiming to build Java EE or Jakarta EE web applications.

? Java Servlet Roadmap

1. Prerequisites


Before diving into Servlets, make sure you're comfortable with:

• Core Java (OOP, collections, exception handling)
• Basic HTML/CSS
• HTTP Protocol (methods like GET, POST, etc.)
• IDE setup (IntelliJ/Eclipse)
• Basic Maven or Gradle usage
• Understanding of web servers (Tomcat, Jetty)

2. Introduction to Servlets

• What is a Servlet?
• Servlet vs JSP vs Frameworks
• Role of a Servlet container (e.g., Apache Tomcat)
• Servlet lifecycle (init(), service(), destroy())

3. Servlet Setup

• Create a simple servlet
• 
  Web deployment using:
  
  • web.xml (deployment descriptor)
  • @WebServlet annotation (Servlet 3.0+)
• 
  Directory structure of a Java web project (WEB-INF, webapp, etc.)
  
  
• 
  Deploy WAR to Tomcat
  

4. Handling HTTP Requests & Responses

• Understanding HttpServletRequest and HttpServletResponse
• doGet() vs doPost()
• Handling form data (query params, form POST)
• Setting content types and response headers
• Redirect vs Forward

5. ServletConfig and ServletContext

• What is ServletConfig and how to use it
• What is ServletContext and application-level data sharing
• Init parameters from web.xml

6. Session Management

• HTTP is stateless — why sessions are needed
• Cookies vs URL rewriting vs Hidden Form Fields
• HttpSession usage (getSession(), invalidate(), setAttribute())
• Session timeout and tracking

7. Request Dispatching

• 
  RequestDispatcher usage
  
  • Forward
  • Include
• 
  Chaining servlets and JSPs
  
  
• 
  Including static content
  

8. File Upload and Download

• Multipart form data parsing (Apache Commons FileUpload or Servlet 3.0+ Part)
• Downloading files using streams
• MIME types and headers for file operations

9. Error Handling in Servlets

• Handling exceptions with web.xml <error-page>
• Custom error messages
• Logging exceptions (using Logger or SLF4J)

10. Filters and Listeners

• 
  Servlet Filters (pre-processing/post-processing requests)
  
  • Authentication, logging, compression, etc.
• 
  Servlet Listeners
  
  • Lifecycle hooks: context, session, attribute events

11. Servlet Best Practices

• Avoid storing sensitive data in plain request/response
• Thread safety — avoid shared mutable state
• Proper session handling
• Use logging libraries
• Modular project structure with MVC approach

12. Integrating with JSP

• When and how to use JSP with Servlets
• Forwarding from Servlet to JSP for view rendering
• Expression Language (EL) and JSTL basics

13. Servlet Security (Basic)

• Authentication and authorization via web.xml
• Securing URLs
• HTTPS and secure cookies
• Form-based login

14. Moving Beyond


After mastering Servlets, you can level up with:

• JSP & JSTL (if not yet)
• MVC frameworks: Spring MVC, JSF
• Hibernate or JPA for DB interaction
• RESTful services using JAX-RS or Spring Boot
• Jakarta EE for modern enterprise development

? Suggested Tools & Libraries

• Apache Tomcat (Servlet container)
• Maven for dependency management
• SLF4J + Logback for logging
• Postman or cURL for testing HTTP requests
• MySQL or H2 for DB integration

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