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  /*
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
   *
   * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved.
   *
   * The contents of this file are subject to the terms of either the GNU
   * General Public License Version 2 only ("GPL") or the Common Development
   * and Distribution License("CDDL") (collectively, the "License").  You
   * may not use this file except in compliance with the License.  You can
  * obtain a copy of the License at
  * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
  * or packager/legal/LICENSE.txt.  See the License for the specific
  * language governing permissions and limitations under the License.
  *
  * When distributing the software, include this License Header Notice in each
  * file and include the License file at packager/legal/LICENSE.txt.
  *
  * GPL Classpath Exception:
  * Oracle designates this particular file as subject to the "Classpath"
  * exception as provided by Oracle in the GPL Version 2 section of the License
  * file that accompanied this code.
  *
  * Modifications:
  * If applicable, add the following below the License Header, with the fields
  * enclosed by brackets [] replaced by your own identifying information:
  * "Portions Copyright [year] [name of copyright owner]"
  *
  * Contributor(s):
  * If you wish your version of this file to be governed by only the CDDL or
  * only the GPL Version 2, indicate your decision by adding "[Contributor]
  * elects to include this software in this distribution under the [CDDL or GPL
  * Version 2] license."  If you don't indicate a single choice of license, a
  * recipient has the option to distribute your version of this file under
  * either the CDDL, the GPL Version 2 or to extend the choice of license to
  * its licensees as provided above.  However, if you add GPL Version 2 code
  * and therefore, elected the GPL Version 2 license, then the option applies
  * only if the new code is made subject to such option by the copyright
  * holder.
  *
  *
  * This file incorporates work covered by the following copyright and
  * permission notice:
  *
  * Copyright 2004 The Apache Software Foundation
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 package javax.servlet;
 
Defines a generic, protocol-independent servlet. To write an HTTP servlet for use on the Web, extend javax.servlet.http.HttpServlet instead.

GenericServlet implements the Servlet and ServletConfig interfaces. GenericServlet may be directly extended by a servlet, although it's more common to extend a protocol-specific subclass such as HttpServlet.

GenericServlet makes writing servlets easier. It provides simple versions of the lifecycle methods init and destroy and of the methods in the ServletConfig interface. GenericServlet also implements the log method, declared in the ServletContext interface.

To write a generic servlet, you need only override the abstract service method.

Author(s):
Various
 
 
  
 public abstract class GenericServlet 
     implements ServletServletConfigjava.io.Serializable
 {
     private static final String LSTRING_FILE = "javax.servlet.LocalStrings";
     private static ResourceBundle lStrings =
         ResourceBundle.getBundle();
 
     private transient ServletConfig config;
    

    
Does nothing. All of the servlet initialization is done by one of the init methods.
    public GenericServlet() { }
    
    
    
Called by the servlet container to indicate to a servlet that the servlet is being taken out of service. See Servlet.destroy().
    public void destroy() {
    }
    
    
    
Returns a String containing the value of the named initialization parameter, or null if the parameter does not exist. See ServletConfig.getInitParameter(java.lang.String).

This method is supplied for convenience. It gets the value of the named parameter from the servlet's ServletConfig object.

Parameters:
name a String specifying the name of the initialization parameter
Returns:
String a String containing the value of the initialization parameter
 
    public String getInitParameter(String name) {
        ServletConfig sc = getServletConfig();
        if (sc == null) {
            throw new IllegalStateException(
                .getString("err.servlet_config_not_initialized"));
        }
        return sc.getInitParameter(name);
    }
    
    
   
Returns the names of the servlet's initialization parameters as an Enumeration of String objects, or an empty Enumeration if the servlet has no initialization parameters. See ServletConfig.getInitParameterNames().

This method is supplied for convenience. It gets the parameter names from the servlet's ServletConfig object.

Returns:
Enumeration an enumeration of String objects containing the names of the servlet's initialization parameters
        ServletConfig sc = getServletConfig();
        if (sc == null) {
            throw new IllegalStateException(
                .getString("err.servlet_config_not_initialized"));
        }
        return sc.getInitParameterNames();
    }   
     

    
Returns this servlet's ServletConfig object.

Returns:
ServletConfig the ServletConfig object that initialized this servlet
    
    public ServletConfig getServletConfig() {
	return ;
    }
 
    
    
Returns a reference to the ServletContext in which this servlet is running. See ServletConfig.getServletContext().

This method is supplied for convenience. It gets the context from the servlet's ServletConfig object.

Returns:
ServletContext the ServletContext object passed to this servlet by the init method
    public ServletContext getServletContext() {
        ServletConfig sc = getServletConfig();
        if (sc == null) {
            throw new IllegalStateException(
                .getString("err.servlet_config_not_initialized"));
        }
        return sc.getServletContext();
    }


    
Returns information about the servlet, such as author, version, and copyright. By default, this method returns an empty string. Override this method to have it return a meaningful value. See Servlet.getServletInfo().

Returns:
String information about this servlet, by default an empty string
    
    public String getServletInfo() {
	return "";
    }


    
Called by the servlet container to indicate to a servlet that the servlet is being placed into service. See Servlet.init(javax.servlet.ServletConfig).

This implementation stores the ServletConfig object it receives from the servlet container for later use. When overriding this form of the method, call super.init(config).

Parameters:
config the ServletConfig object that contains configutation information for this servlet
Throws:
ServletException if an exception occurs that interrupts the servlet's normal operation
See also:
UnavailableException
    public void init(ServletConfig configthrows ServletException {
	this. = config;
	this.init();
    }


    
A convenience method which can be overridden so that there's no need to call super.init(config).

Instead of overriding init(javax.servlet.ServletConfig), simply override this method and it will be called by GenericServlet.init(ServletConfig config). The ServletConfig object can still be retrieved via getServletConfig().

Throws:
ServletException if an exception occurs that interrupts the servlet's normal operation
    public void init() throws ServletException {
    }
    

    
Writes the specified message to a servlet log file, prepended by the servlet's name. See ServletContext.log(java.lang.String).

Parameters:
msg a String specifying the message to be written to the log file
     
    public void log(String msg) {
	getServletContext().log(getServletName() + ": "msg);
    }
   
   
    
Writes an explanatory message and a stack trace for a given Throwable exception to the servlet log file, prepended by the servlet's name. See ServletContext.log(java.lang.String,java.lang.Throwable).

Parameters:
message a String that describes the error or exception
t the java.lang.Throwable error or exception
   
    public void log(String messageThrowable t) {
	getServletContext().log(getServletName() + ": " + messaget);
    }
    
    
    
Called by the servlet container to allow the servlet to respond to a request. See Servlet.service(javax.servlet.ServletRequest,javax.servlet.ServletResponse).

This method is declared abstract so subclasses, such as HttpServlet, must override it.

Parameters:
req the ServletRequest object that contains the client's request
res the ServletResponse object that will contain the servlet's response
Throws:
ServletException if an exception occurs that interferes with the servlet's normal operation occurred
java.io.IOException if an input or output exception occurs
    public abstract void service(ServletRequest reqServletResponse res)
	throws ServletExceptionIOException;
    

    
Returns the name of this servlet instance. See ServletConfig.getServletName().

Returns:
the name of this servlet instance
    public String getServletName() {
        ServletConfig sc = getServletConfig();
        if (sc == null) {
            throw new IllegalStateException(
                .getString("err.servlet_config_not_initialized"));
        }
        return sc.getServletName();
    }
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