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Overview of Servlet Methods

Servlet Methods Overview

Overview of Servlet Methods

A Generic servlet contains the following five methods:

init()

public void init(ServletConfig config) throws ServletException

The init() method is called only once by the servlet container throughout the life of a servlet. This method allows the servlet to initialize and be placed into service.

The servlet cannot be put into service if:

  • The init() method does not return within a fixed time set by the web server.
  • It throws a ServletException.

Parameters: The init() method takes a ServletConfig object containing initialization parameters and servlet configuration and throws a ServletException if an exception occurs.

service()

public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException

Once the servlet starts receiving requests, the service() method is called by the servlet container to respond. The servlet uses ServletRequest and ServletResponse objects to handle client requests and responses.

The status code of the response should always be set for a servlet that throws or sends an error.

Parameters: The service() method takes a ServletRequest object containing the client's request and a ServletResponse object containing the servlet's response. It throws ServletException and IOException exceptions.

getServletConfig()

public ServletConfig getServletConfig()

This method returns a ServletConfig object that contains parameters for initialization and startup of the servlet. This object is passed to the init method. The generic class implementing this interface stores the ServletConfig object to return it.

Returns: The ServletConfig object.

getServletInfo()

public String getServletInfo()

This method returns information about the servlet such as version and author. The information should be in plain text, not markup.

Returns: A string containing information about the servlet.

destroy()

public void destroy()

The destroy() method is called when the servlet is to be closed. Before removing a servlet instance from service, the servlet container calls the destroy() method. After calling destroy(), no service methods will be called. This method allows the servlet to clean up resources like memory and threads.

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