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What is servlet in java? Discuss its life cycle.

 A servlet in Java is a server-side program that runs on a web server and receives and responds to HTTP requests from clients, such as web browsers. It is a Java class that extends the javax.servlet.http.HttpServlet class and implements the javax.servlet.Servlet interface.


The life cycle of a servlet consists of several stages that are executed in a particular order:

  1. Loading: When a request is made for a servlet, the web server checks whether the servlet is already loaded or not. If the servlet is not loaded, the web server loads the servlet by creating an instance of the servlet class and invoking its init() method.
  2. Initialization: After the servlet is loaded, the web server calls the servlet's init() method, which is used to initialize the servlet. The init() method is called only once during the life cycle of the servlet. It is typically used to perform one-time initialization tasks, such as opening a database connection or initializing global variables.
  3. Request handling: After the servlet is initialized, it is ready to handle requests. Each time a client makes a request to the servlet, the web server creates a new thread to handle the request and invokes the servlet's service() method. The service() method reads the request, processes it, and sends a response back to the client.
  4. Destroying: When the web server shuts down or decides to unload the servlet, it calls the servlet's destroy() method. This method is used to perform cleanup tasks, such as closing database connections or releasing system resources.
  5. Unloading: Finally, the web server unloads the servlet by removing it from memory. This happens when the web server shuts down or when the servlet is no longer needed.

In summary, the life cycle of a servlet includes loading, initialization, request handling, destroying, and unloading. Each stage of the life cycle is executed in a specific order and is designed to perform a specific task.

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