servlet.java

这是<java高级实用教程>的电子版书,内容深入浅出啊,有实例有解析,不错的

// Servlet - the servlet interface
//
// API based on documentation from JavaSoft.
//
// Copyright (C) 1996,1998 by Jef Poskanzer <[e-mail]>. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// Visit the ACME Labs Java page for up-to-date versions of this and other
// fine Java utilities: http://www.acme.com/java/

package Acme.Serve.servlet;

import java.io.*;

/// The servlet interface.
// <P>
// Servlets are little Java programs that can be hooked into a
// server and run in response to requests.
// <P>
// Servlet has to be an interface so that things that must inherit
// from another object, such as RMI, can also be Servlets.  However,
// most of the time a Servlet will not need to be anything else, and
// it will be somewhat more convenient to extend GenericServlet.
// <P>
// This is taken from JavaSoft's Servlet API documentation.
// <P>
// <A HREF="/resources/classes/Acme/Serve/servlet/Servlet.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>
// <P>
// @see Acme.Serve.servlet.GenericServlet
// @see Acme.Serve.servlet.http.HttpServlet
// @see Acme.Serve.SampleServlet
// @see Acme.Serve.Serve

public interface Servlet
    {

    /// Initializes the servlet.
    // This is called by the system when the servlet is first loaded.
    // @param config servlet initialization information
    // @exception ServletException when an exception has occurred
    public void init( ServletConfig config ) throws ServletException;

    /// Returns a servlet config object, which contains any initialization
    // parameters and startup configuration for this servlet.
    public ServletConfig getServletConfig();

    /// Services a single request from the client.
    // <P>
    // Note that the server only creates a single instance of your Servlet
    // subclass, and calls the service() method of that one instance multiple
    // times, possibly at the same time in different threads.  This is somewhat
    // unusual in the Java world.  The implication is that any instance
    // variables in your class behave more like class variables - they are
    // shared among multiple concurrent calls.  So, be careful.
    // @param req the servlet request
    // @param req the servlet response
    // @exception ServletException when a servlet exception has occurred
    // @exception IOException when an I/O exception has occurred
    public void service( ServletRequest req, ServletResponse res ) throws ServletException, IOException;

    /// Returns a string containing information about the author, version, and
    // copyright of the servlet.
    public String getServletInfo();

    /// Destroys the servlet and cleans up whatever resources are being held.
    // This is called by the system when the servlet is being destroyed.
    public void destroy();

    }