Jetty example source code file (GenericServlet.java)

This example Jetty source code file (GenericServlet.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Jetty tags/keywords

enumeration, genericservlet, illegalstateexception, illegalstateexception, io, ioexception, lstring_file, servletconfig, servletconfig, servletexception, servletexception, servletresponse, string, string, throwable, util

The Jetty GenericServlet.java source code

/*
 * The contents of this file are subject to the terms
 * of the Common Development and Distribution License
 * (the "License").  You may not use this file except
 * in compliance with the License.
 *
 * You can obtain a copy of the license at
 * glassfish/bootstrap/legal/CDDLv1.0.txt or
 * https://glassfish.dev.java.net/public/CDDLv1.0.html.
 * See the License for the specific language governing
 * permissions and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL
 * HEADER in each file and include the License file at
 * glassfish/bootstrap/legal/CDDLv1.0.txt.  If applicable,
 * add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your
 * own identifying information: Portions Copyright [yyyy]
 * [name of copyright owner]
 *
 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
 *
 * Portions Copyright Apache Software Foundation.
 */ 

package javax.servlet;

import java.io.IOException;
import java.util.Enumeration;
import java.util.ResourceBundle;

/**
 *
 * Defines a generic, protocol-independent
 * servlet. To write an HTTP servlet for use on the
 * Web, extend {@link javax.servlet.http.HttpServlet} instead.
 *
 * <p>GenericServlet implements the Servlet
 * and <code>ServletConfig interfaces. GenericServlet
 * may be directly extended by a servlet, although it's more common to extend
 * a protocol-specific subclass such as <code>HttpServlet.
 *
 * <p>GenericServlet makes writing servlets
 * easier. It provides simple versions of the lifecycle methods 
 * <code>init and destroy and of the methods 
 * in the <code>ServletConfig interface. GenericServlet
 * also implements the <code>log method, declared in the
 * <code>ServletContext interface. 
 *
 * <p>To write a generic servlet, you need only
 * override the abstract <code>service method. 
 *
 *
 * @author 	Various
 */

 
public abstract class GenericServlet 
    implements Servlet, ServletConfig, java.io.Serializable
{
    private static final String LSTRING_FILE = "javax.servlet.LocalStrings";
    private static ResourceBundle lStrings =
        ResourceBundle.getBundle(LSTRING_FILE);

    private transient ServletConfig config;
    

    /**
     *
     * Does nothing. All of the servlet initialization
     * is done by one of the <code>init methods.
     *
     */

    public GenericServlet() { }
    
    
    
   /**
     * Called by the servlet container to indicate to a servlet that the
     * servlet is being taken out of service.  See {@link Servlet#destroy}.
     *
     * 
     */

    public void destroy() {
    }
    
    
    
    /**
     * Returns a <code>String containing the value of the named
     * initialization parameter, or <code>null if the parameter does
     * not exist.  See {@link ServletConfig#getInitParameter}.
     *
     * <p>This method is supplied for convenience. It gets the 
     * value of the named parameter from the servlet's 
     * <code>ServletConfig object.
     *
     * @param name 		a <code>String specifying the name 
     *				of the initialization parameter
     *
     * @return String 		a <code>String containing the value
     *				of the initialization parameter
     *
     */ 

    public String getInitParameter(String name) {
        ServletConfig sc = getServletConfig();
        if (sc == null) {
            throw new IllegalStateException(
                lStrings.getString("err.servlet_config_not_initialized"));
        }

        return sc.getInitParameter(name);
    }
    
    

   /**
    * Returns the names of the servlet's initialization parameters 
    * as an <code>Enumeration of String objects,
    * or an empty <code>Enumeration if the servlet has no
    * initialization parameters.  See {@link
    * ServletConfig#getInitParameterNames}.
    *
    * <p>This method is supplied for convenience. It gets the 
    * parameter names from the servlet's <code>ServletConfig object. 
    *
    *
    * @return Enumeration 	an enumeration of <code>String
    *				objects containing the names of 
    *				the servlet's initialization parameters
    *
    */

    public Enumeration getInitParameterNames() {
        ServletConfig sc = getServletConfig();
        if (sc == null) {
            throw new IllegalStateException(
                lStrings.getString("err.servlet_config_not_initialized"));
        }

        return sc.getInitParameterNames();
    }   
    
     
 
     

    /**
     * Returns this servlet's {@link ServletConfig} object.
     *
     * @return ServletConfig 	the <code>ServletConfig object
     *				that initialized this servlet
     *
     */
    
    public ServletConfig getServletConfig() {
	return config;
    }
    
    
 
    
    /**
     * Returns a reference to the {@link ServletContext} in which this servlet
     * is running.  See {@link ServletConfig#getServletContext}.
     *
     * <p>This method is supplied for convenience. It gets the 
     * context from the servlet's <code>ServletConfig object.
     *
     *
     * @return ServletContext 	the <code>ServletContext object
     *				passed to this servlet by the <code>init
     *				method
     *
     */

    public ServletContext getServletContext() {
        ServletConfig sc = getServletConfig();
        if (sc == null) {
            throw new IllegalStateException(
                lStrings.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 {@link
     * Servlet#getServletInfo}.
     *
     *
     * @return 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 {@link Servlet#init}.
     *
     * <p>This implementation stores the {@link ServletConfig}
     * object it receives from the servlet container for later use.
     * When overriding this form of the method, call 
     * <code>super.init(config).
     *
     * @param config 			the <code>ServletConfig object
     *					that contains configutation
     *					information for this servlet
     *
     * @exception ServletException 	if an exception occurs that
     *					interrupts the servlet's normal
     *					operation
     *
     * 
     * @see 				UnavailableException
     *
     */

    public void init(ServletConfig config) throws ServletException {
	this.config = config;
	this.init();
    }





    /**
     *
     * A convenience method which can be overridden so that there's no need
     * to call <code>super.init(config).
     *
     * <p>Instead of overriding {@link #init(ServletConfig)}, simply override
     * this method and it will be called by
     * <code>GenericServlet.init(ServletConfig config).
     * The <code>ServletConfig object can still be retrieved via {@link
     * #getServletConfig}. 
     *
     * @exception 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 {@link ServletContext#log(String)}.
     *
     * @param msg 	a <code>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 <code>Throwable exception
     * to the servlet log file, prepended by the servlet's name.
     * See {@link ServletContext#log(String, Throwable)}.
     *
     *
     * @param message 		a <code>String that describes
     *				the error or exception
     *
     * @param t			the <code>java.lang.Throwable error
     * 				or exception
     *
     *
     */
   
    public void log(String message, Throwable t) {
	getServletContext().log(getServletName() + ": " + message, t);
    }
    
    
    
    /**
     * Called by the servlet container to allow the servlet to respond to
     * a request.  See {@link Servlet#service}.
     * 
     * <p>This method is declared abstract so subclasses, such as 
     * <code>HttpServlet, must override it.
     *
     *
     *
     * @param req 	the <code>ServletRequest object
     *			that contains the client's request
     *
     * @param res 	the <code>ServletResponse object
     *			that will contain the servlet's response
     *
     * @exception ServletException 	if an exception occurs that
     *					interferes with the servlet's
     *					normal operation occurred
     *
     * @exception IOException 		if an input or output
     *					exception occurs
     *
     */

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


    /**
     * Returns the name of this servlet instance.
     * See {@link ServletConfig#getServletName}.
     *
     * @return          the name of this servlet instance
     *
     *
     *
     */

    public String getServletName() {
        ServletConfig sc = getServletConfig();
        if (sc == null) {
            throw new IllegalStateException(
                lStrings.getString("err.servlet_config_not_initialized"));
        }

        return sc.getServletName();
    }
}