Understanding Servlet Concepts in Java

What is a servlet in Java?

• A servlet is a programming language used for mobile applications.

• A servlet in Java is a server-side component that processes requests and generates responses, often used for web applications.

• A servlet is a client-side application that runs in a web browser.

• A servlet is a type of database used for storing data.

Answer explanation

A servlet is a server-side component in Java that handles client requests and generates responses, making it essential for web applications. This distinguishes it from client-side applications and databases.

How does a servlet differ from a CGI program?

• Servlets are slower and do not maintain state.

• Servlets require more memory than CGI programs.

• CGI programs are more efficient and run in the same process for each request.

• Servlets are more efficient and maintain state, while CGI programs are separate processes for each request.

Answer explanation

Servlets are more efficient because they run within the same Java process and can maintain state across requests, unlike CGI programs, which create a new process for each request, making them less efficient.

What is the lifecycle of a servlet?

• Loading, initialization, and caching only.

• Request handling and response generation only.

• The lifecycle of a servlet includes loading, initialization, request handling, and destruction.

• Initialization, request handling, and logging.

Answer explanation

The correct choice outlines the complete lifecycle of a servlet, which includes loading, initialization, request handling, and destruction. Other options miss key stages in the servlet lifecycle.

What are the main interfaces of the Servlet API?

• HttpRequest

• HttpResponse

• HttpServlet, ServletRequest, ServletResponse, ServletConfig, ServletContext

• ServletHandler

Answer explanation

The main interfaces of the Servlet API include HttpServlet, ServletRequest, ServletResponse, ServletConfig, and ServletContext. These are essential for handling requests and responses in a web application.

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

• The init() method is responsible for logging servlet errors.

• The init() method initializes the servlet and prepares it to handle requests.

• The init() method handles HTTP requests directly.

• The init() method is used to destroy the servlet instance.

Answer explanation

The init() method is crucial for initializing a servlet, allowing it to set up resources and configurations before handling incoming requests. This makes the second choice the correct answer.

How do you handle HTTP requests in a servlet?

• Override doGet() and/or doPost() methods in the servlet.

• Use the GET method exclusively for all requests.

• Implement a custom HTTP handler instead of using servlets.

• Ignore HTTP methods and process all requests the same way.

Answer explanation

To handle HTTP requests in a servlet, you should override the doGet() and/or doPost() methods. This allows the servlet to process GET and POST requests appropriately, making it the correct approach.

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

• The service() method initializes the servlet only.

• The service() method handles database connections.

• The service() method processes client requests and generates responses in a servlet.

• The service() method is used for session management.

Answer explanation

The service() method is crucial in a servlet as it processes client requests and generates responses, making it the core of request handling. Other options do not accurately describe its primary function.

What is the difference between doGet() and doPost() methods?

• doGet() retrieves data; doPost() sends data.

• doGet() is synchronous; doPost() is asynchronous.

• doGet() sends data; doPost() retrieves data.

• doGet() is used for file uploads; doPost() is for data retrieval.

Answer explanation

The correct choice is that doGet() retrieves data while doPost() sends data. doGet() is typically used for fetching resources, whereas doPost() is used for submitting data to be processed.

How can you access servlet parameters?

• Use HttpServletRequest.getParameter(String name) to access servlet parameters.

• Access servlet parameters through the ServletContext.getParameter(String name) method.

• Use HttpServletResponse.getParameter(String name) to access servlet parameters.

• Retrieve servlet parameters using HttpServletRequest.getAttribute(String name) instead.

Answer explanation

The correct way to access servlet parameters is by using HttpServletRequest.getParameter(String name). This method retrieves the value of a parameter sent in the request, making it the appropriate choice for accessing servlet parameters.

What is the use of the ServletConfig interface?

• The ServletConfig interface is used to provide configuration information to a servlet.

• To manage database connections for servlets.

• To handle HTTP requests and responses directly.

• To define the lifecycle methods of a servlet.

Answer explanation

The ServletConfig interface is essential for providing configuration information to a servlet, such as initialization parameters. This allows servlets to access specific settings defined in the web application deployment descriptor.