ibarrygao / my-notes Goto Github PK

/**
 * Called by the servlet container to indicate to a servlet that the servlet
 * is being placed into service.
 *
 * <p>
 * The servlet container calls the <code>init</code> method exactly once
 * after instantiating the servlet. The <code>init</code> method must
 * complete successfully before the servlet can receive any requests.
 *
 * <p>
 * The servlet container cannot place the servlet into service if the
 * <code>init</code> method
 * <ol>
 * <li>Throws a <code>ServletException</code>
 * <li>Does not return within a time period defined by the Web server
 * </ol>
 *
 *
 * @param config
 *            a <code>ServletConfig</code> object containing the servlet's
 *            configuration and initialization parameters
 *
 * @exception ServletException
 *                if an exception has occurred that interferes with the
 *                servlet's normal operation
 *
 * @see UnavailableException
 * @see #getServletConfig
 */
public void init(ServletConfig config) throws ServletException;

/**
 *
 * Returns a {@link ServletConfig} object, which contains initialization and
 * startup parameters for this servlet. The <code>ServletConfig</code>
 * object returned is the one passed to the <code>init</code> method.
 *
 * <p>
 * Implementations of this interface are responsible for storing the
 * <code>ServletConfig</code> object so that this method can return it. The
 * {@link GenericServlet} class, which implements this interface, already
 * does this.
 *
 * @return the <code>ServletConfig</code> object that initializes this
 *         servlet
 *
 * @see #init
 */
public ServletConfig getServletConfig();

/**
 * Called by the servlet container to allow the servlet to respond to a
 * request.
 *
 * <p>
 * This method is only called after the servlet's <code>init()</code> method
 * has completed successfully.
 *
 * <p>
 * The status code of the response always should be set for a servlet that
 * throws or sends an error.
 *
 *
 * <p>
 * Servlets typically run inside multithreaded servlet containers that can
 * handle multiple requests concurrently. Developers must be aware to
 * synchronize access to any shared resources such as files, network
 * connections, and as well as the servlet's class and instance variables.
 * More information on multithreaded programming in Java is available in <a
 * href
 * ="http://java.sun.com/Series/Tutorial/java/threads/multithreaded.html">
 * the Java tutorial on multi-threaded programming</a>.
 *
 *
 * @param req
 *            the <code>ServletRequest</code> object that contains the
 *            client's request
 *
 * @param res
 *            the <code>ServletResponse</code> object that contains the
 *            servlet's response
 *
 * @exception ServletException
 *                if an exception occurs that interferes with the servlet's
 *                normal operation
 *
 * @exception IOException
 *                if an input or output exception occurs
 */
public void service(ServletRequest req, ServletResponse res)
        throws ServletException, IOException;

/**
 * Returns information about the servlet, such as author, version, and
 * copyright.
 *
 * <p>
 * The string that this method returns should be plain text and not markup
 * of any kind (such as HTML, XML, etc.).
 *
 * @return a <code>String</code> containing servlet information
 */
public String getServletInfo();

/**
 * Called by the servlet container to indicate to a servlet that the servlet
 * is being taken out of service. This method is only called once all
 * threads within the servlet's <code>service</code> method have exited or
 * after a timeout period has passed. After the servlet container calls this
 * method, it will not call the <code>service</code> method again on this
 * servlet.
 *
 * <p>
 * This method gives the servlet an opportunity to clean up any resources
 * that are being held (for example, memory, file handles, threads) and make
 * sure that any persistent state is synchronized with the servlet's current
 * state in memory.
 */
public void destroy();