What is the lifecycle of servlets and what stages…

The servlet lifecycle is managed by the servlet container. It goes through the following stages:

Loading: The container loads the servlet class.
Instantiation: A single instance of the servlet is created using the Class.newInstance() method. Servlets are singletons within the application context.
Initialization: The container calls the init(ServletConfig config) method. This method is called only once during the entire lifecycle of the servlet. It is used for initialization tasks such as reading configuration parameters, establishing database connections, etc.
```
// Example init() method
public void init(ServletConfig config) throws ServletException {
    super.init(config);
    // Initialize resources
    System.out.println("Servlet initialized.");
}
```

Request Handling: The servlet is ready to process client requests. For each incoming request, the container creates a new thread and calls the service(ServletRequest request, ServletResponse response) method. The service() method typically delegates request processing to other specific methods such as doGet(), doPost(), doPut(), doDelete() depending on the HTTP request type.

// Example service() method
public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException {
    // Delegate request processing
    super.service(request, response);
}

// Example doGet() method
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    out.println("<h1>Hello from the servlet!</h1>");
}

Destruction: When the container decides to unload the servlet (for example, when stopping the application), it calls the destroy() method. This method is called only once before the servlet instance is destroyed. It is used for releasing resources such as closing database connections, clearing caches, etc.
```
// Example destroy() method
public void destroy() {
    // Release resources
    System.out.println("Servlet destroyed.");
}
```

In summary, the stages can be represented in a table:

Stage	Method called by container	Description	Called once
Class loading	-	The servlet class is loaded into memory	Once
Instance creation	`Class.newInstance()`	An instance of the servlet is created	Once
Initialization	`init(ServletConfig config)`	Performs initialization tasks	Once
Request processing	`service(...)`, `doGet(...)`, `doPost(...)`, etc.	Handles incoming client requests	Multiple times
Destruction	`destroy()`	Releases resources before the servlet instance is removed	Once

What is the lifecycle of servlets and what stages does it include?