Author Archives: Stanislav_Panteleev

🧠 What is URL Encoding? ✅ URL encoding is the process of translating special characters in a URL into a format that can be safely transmitted over the Internet. In URLs: Only letters, digits, and a few special characters (-, … Continue reading →

🧠 What is SingleThreadModel? ✅ SingleThreadModel is an interface that was introduced in early Servlet API versions (Servlet 2.0) to guarantee that: Only one thread can execute the servlet’s service() method at a time per servlet instance. 🎯 How It … Continue reading →

❌ No, you cannot use both PrintWriter and ServletOutputStream simultaneously in a servlet for the same response. It is forbidden by the Servlet specification.Mixing them causes IllegalStateException. 🧠 Why? The response can either be character-based (PrintWriter) or byte-based (ServletOutputStream). Not … Continue reading →

Both are used to send data from your servlet back to the client as part of the HTTP response. But they are a little different: Feature PrintWriter ServletOutputStream Data type Character stream (text data) Byte stream (binary data) Best for … Continue reading →

🧠 Main Differences Between GET and POST Feature GET POST Where data is sent In the URL as query string (?key=value) In the HTTP request body Visibility Data is visible in the URL Data is hidden (not shown in URL) … Continue reading →

🧠 How Can a Client Send Data to the Server? There are several ways a client (like a browser or app) can send data to a server: 🎯 1. Using HTTP GET Parameters Data is sent in the URL as … Continue reading →

🧠 First: What is an immutable HTTP method? In HTTP, a method is considered immutable (or safe) if: It does NOT change anything on the server. It’s supposed to be read-only (just retrieves data). ✅ Examples of immutable (safe) methods: … Continue reading →

The short answer is:👉 Yes, you absolutely should worry about thread safety when working with servlets. Let’s break this down very clearly: 🧠 Why? In a servlet container (like Tomcat, Jetty, etc.),only one instance of your servlet class is created … Continue reading →

🧠 Main Methods in HttpServlet Here’s the main methods grouped by their purpose: Purpose Method Description Core dispatching service(HttpServletRequest req, HttpServletResponse resp) Dispatches the HTTP request to doGet(), doPost(), etc., based on HTTP method Handle GET request doGet(HttpServletRequest req, HttpServletResponse … Continue reading →

✅ Because it is designed to be extended, not used directly. HttpServlet provides basic HTTP-specific functionality: It implements the service() method to automatically dispatch requests based on the HTTP method (GET, POST, PUT, DELETE, etc.). But it does not know … Continue reading →