#4 Life Cycle of Servlet || init() service() destroy() methods of Servlet Hindi

Summary

This video explains the servlet life cycle in a web server environment, using Tomcat as an example. It covers key stages such as loading and instantiation, where the servlet class is loaded and an object is created; initialization, where the servlet is set up using an init() method; request handling, where the servlet processes client requests with threading support; and destruction, where the servlet cleans up resources and is destroyed upon server shutdown. The speaker emphasizes the importance of each stage and provides detailed explanations, ensuring viewers understand how servlets handle requests efficiently.

Takeaways

• 😀 The script explains the Servlet lifecycle in detail, emphasizing each step with examples.
• 😀 The first stage of the lifecycle is 'Loading and Instantiation', where the Servlet class is loaded into memory.
• 😀 When the server starts, a Servlet object is created and stored in memory.
• 😀 The second stage, 'Initialization', involves initializing the Servlet object through the init() method.
• 😀 The init() method is responsible for initializing the Servlet object and any values that need to be inserted.
• 😀 The third stage, 'Request Handling', involves the Servlet receiving and handling requests from the client.
• 😀 The service() method is invoked to handle requests based on their type (GET or POST).
• 😀 Multithreading is used in request handling, where each request creates a new thread to handle it separately.
• 😀 The script highlights that the lifecycle methods like init(), service(), and destroy() are executed only once during server start and shutdown.
• 😀 The last stage of the lifecycle is 'Destruction', where the destroy() method is executed when the server shuts down, deleting the Servlet object.
• 😀 The script explains that resources such as database connections or files are closed before the Servlet object is destroyed during server shutdown.

Q & A

What is the first stage in the servlet life cycle?

The first stage is 'Loading and Instantiation'. During this stage, the servlet class is loaded into memory, and the servlet object is created when the server (like Tomcat) starts.

How does the initialization phase work in the servlet life cycle?

In the initialization phase, the servlet's 'init()' method is called. This method is used to initialize the servlet object, allowing you to set up any necessary configurations or parameters.

What happens when a client sends a request in the servlet life cycle?

When a client sends a request, the 'service()' method is invoked. This method determines the type of request (GET or POST) and calls the corresponding method ('doGet()' or 'doPost()') to handle the request.

What is the purpose of the 'service()' method in a servlet?

The 'service()' method in a servlet is responsible for processing the client's request. It determines the type of the request (GET, POST, etc.) and delegates the processing to the appropriate method, such as 'doGet()' or 'doPost()'.

How does multithreading work in the servlet life cycle?

In the servlet life cycle, when a request is received, a new thread is created to handle that specific request. This enables the server to process multiple requests simultaneously, improving its efficiency.

What happens during the destruction phase of the servlet life cycle?

During the destruction phase, the 'destroy()' method is called when the server shuts down. This method is used to clean up any resources, such as database connections or file handles, and to delete the servlet object from memory.

What does the 'destroy()' method do in the servlet life cycle?

The 'destroy()' method is responsible for cleaning up the servlet before the server shuts down. It deletes any resources that were open during the servlet's operation and removes the servlet object from memory.

What is the role of the 'init()' method in servlet initialization?

The 'init()' method is called during the initialization phase. It initializes the servlet object and allows for any necessary setup, such as inserting configuration parameters or initializing resources.

How does the server know which method to call for a specific request?

The server determines which method to call based on the type of the request. If the request is a GET request, the 'doGet()' method is called. If it is a POST request, the 'doPost()' method is invoked.

What is the significance of multithreading in servlet handling?

Multithreading allows the servlet to handle multiple client requests simultaneously. Each request is handled by a separate thread, improving the server's efficiency and responsiveness.