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If you want your servlet to initialize immediately when the web application starts (instead of waiting for the first request), the solution is simple and powerful: ✅ Use load-on-startup in web.xml This tells the servlet container to load and initialize … Continue reading →

Servlet Filters and Servlet Listeners are both powerful tools — but they serve very different purposes. Let’s break it down: 🧭 TL;DR: When to Use What Feature Use Filters When… Use Listeners When… 🔁 Request/Response You want to modify or … Continue reading →

🎯 Why Use Listeners? They let you hook into the lifecycle of: The ServletContext (entire app) HttpSession (per user) ServletRequest (per request) You use them to: Initialize or clean up resources (e.g. DB pools) Log application or session events Track … Continue reading →

Servlet filters are like middleware in Java web applications — they allow you to intercept and modify requests and responses before they reach a servlet or after the servlet processes them. 🧰 What Is a Servlet Filter? A filter is … Continue reading →

The servlet container (like Tomcat, Jetty, or Undertow) does a lot of behind-the-scenes heavy lifting so your servlet code can focus just on business logic. Let’s look at the most common and critical tasks a servlet container performs: ⚙️ Most … Continue reading →

🧠 There Are Two init() Methods in Servlets: 📌 So… why is it usually enough (and preferred) to override only the no-arg init()? Here’s the Explanation: 1. Servlet API Design Handles ServletConfig for You If your servlet extends HttpServlet, then … Continue reading →

Technically, yes, you can define a constructor in a servlet, but… ⚠️ You Should Avoid Putting Initialization Logic in It. Here’s why: 🚫 Why Not Use Constructor for Initialization? Servlet container controls instantiation — not you. ServletConfig and ServletContext are … Continue reading →

In most servlet-based applications, you don’t need to override the service() method — you override doGet(), doPost(), etc. But there are specific situations where overriding service() makes sense. 🧠 First, What Does service() Do? The service() method is part of … Continue reading →

🛠️ Steps to Create a Servlet (Classic web.xml Approach) ✅ 1. Create a Java Class That Extends HttpServlet ✅ 2. Compile the Servlet Make sure to include the servlet API jar in your classpath: ✅ 3. Create a Deployment Structure … Continue reading →

📄 What is it exactly? ➤ File Name: ➤ It’s read by the servlet container (like Tomcat) when deploying your app. 🧠 What It Does: Maps URLs to servlets Declares filters, listeners Configures session settings Sets up security (authentication, roles) … Continue reading →