All Downloads are FREE. Search and download functionalities are using the official Maven repository.

javax.servlet.GenericFilter Maven / Gradle / Ivy

The newest version!
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 1997-2017 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://oss.oracle.com/licenses/CDDL+GPL-1.1
 * or 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 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.
 */

package javax.servlet;

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

/**
 *
 * 

Defines a generic, protocol-independent * filter. To write an HTTP filter for use on the * Web, extend {@link javax.servlet.http.HttpFilter} instead.

* *

GenericFilter implements the Filter * and FilterConfig interfaces. GenericFilter * may be directly extended by a filter, although it's more common to extend * a protocol-specific subclass such as HttpFilter. * *

GenericFilter makes writing filters * easier. It provides simple versions of the lifecycle methods * init and destroy and of the methods * in the FilterConfig interface. * *

To write a generic filter, you need only * override the abstract doFilter method. * * @author Various * * @since Servlet 4.0 */ public abstract class GenericFilter implements Filter, FilterConfig, java.io.Serializable { private static final String LSTRING_FILE = "javax.servlet.LocalStrings"; private static final ResourceBundle lStrings = ResourceBundle.getBundle(LSTRING_FILE); private transient FilterConfig config; /** * *

Does nothing. All of the filter initialization * is done by one of the init methods.

* * @since Servlet 4.0 */ public GenericFilter() { } /** *

Returns a String containing the value of the named * initialization parameter, or null if the parameter does * not exist. See {@link FilterConfig#getInitParameter}.

* *

This method is supplied for convenience. It gets the * value of the named parameter from the servlet's * ServletConfig object. * * @param name a String specifying the name * of the initialization parameter * * @return String a String containing the value * of the initialization parameter * * @since Servlet 4.0 * */ @Override public String getInitParameter(String name) { FilterConfig fc = getFilterConfig(); if (fc == null) { throw new IllegalStateException( lStrings.getString("err.filter_config_not_initialized")); } return fc.getInitParameter(name); } /** *

Returns the names of the filter's initialization parameters * as an Enumeration of String objects, * or an empty Enumeration if the filter has no * initialization parameters. See {@link * FilterConfig#getInitParameterNames}.

* *

This method is supplied for convenience. It gets the * parameter names from the filter's FilterConfig object. * * @return Enumeration an enumeration of String * objects containing the names of * the filter's initialization parameters * * @since Servlet 4.0 */ @Override public Enumeration getInitParameterNames() { FilterConfig fc = getFilterConfig(); if (fc == null) { throw new IllegalStateException( lStrings.getString("err.filter_config_not_initialized")); } return fc.getInitParameterNames(); } /** *

Returns this servlet's {@link ServletConfig} object.

* * @return FilterConfig the FilterConfig object * that initialized this filter * * @since Servlet 4.0 */ public FilterConfig getFilterConfig() { return config; } /** *

Returns a reference to the {@link ServletContext} in which this filter * is running. See {@link FilterConfig#getServletContext}.

* *

This method is supplied for convenience. It gets the * context from the filter's FilterConfig object. * * @return ServletContext the ServletContext object * passed to this filter by the init * method * * @since Servlet 4.0 */ @Override public ServletContext getServletContext() { FilterConfig sc = getFilterConfig(); if (sc == null) { throw new IllegalStateException( lStrings.getString("err.filter_config_not_initialized")); } return sc.getServletContext(); } /** *

Called by the servlet container to indicate to a filter that * it is being placed into service. See {@link Filter#init}.

* *

This implementation stores the {@link FilterConfig} * object it receives from the servlet container for later use. * When overriding this form of the method, call * super.init(config). * * @param config the FilterConfig object * that contains configuration * information for this filter * * @exception ServletException if an exception occurs that * interrupts the servlet's normal * operation * * @see UnavailableException * * @since Servlet 4.0 */ @Override public void init(FilterConfig config) throws ServletException { this.config = config; this.init(); } /** *

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

* *

Instead of overriding {@link #init(FilterConfig)}, simply override * this method and it will be called by * GenericFilter.init(FilterConfig config). * The FilterConfig object can still be retrieved via {@link * #getFilterConfig}. * * @exception ServletException if an exception occurs that * interrupts the servlet's * normal operation * * @since Servlet 4.0 */ public void init() throws ServletException { } /** *

Returns the name of this filter instance. * See {@link FilterConfig#getFilterName}.

* * @return the name of this filter instance * * @since Servlet 4.0 */ @Override public String getFilterName() { FilterConfig sc = getFilterConfig(); if (sc == null) { throw new IllegalStateException( lStrings.getString("err.servlet_config_not_initialized")); } return sc.getFilterName(); } }




© 2015 - 2024 Weber Informatics LLC | Privacy Policy