Java tutorial
/* * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.naming; import java.util.Hashtable; /** * This abstract class is used to represent a referral exception, * which is generated in response to a <em>referral</em> * such as that returned by LDAP v3 servers. * <p> * A service provider provides * a subclass of {@code ReferralException} by providing implementations * for {@code getReferralInfo()} and {@code getReferralContext()} (and appropriate * constructors and/or corresponding "set" methods). * <p> * The following code sample shows how {@code ReferralException} can be used. * <blockquote><pre>{@code * while (true) { * try { * bindings = ctx.listBindings(name); * while (bindings.hasMore()) { * b = bindings.next(); * ... * } * break; * } catch (ReferralException e) { * ctx = e.getReferralContext(); * } * } * }</pre></blockquote> *<p> * {@code ReferralException} is an abstract class. Concrete implementations * determine its synchronization and serialization properties. *<p> * An environment parameter passed to the {@code getReferralContext()} * method is owned by the caller. * The service provider will not modify the object or keep a reference to it, * but may keep a reference to a clone of it. * * @author Rosanna Lee * @author Scott Seligman * * @since 1.3 * */ public abstract class ReferralException extends NamingException { /** * Constructs a new instance of ReferralException using the * explanation supplied. All other fields are set to null. * * @param explanation Additional detail about this exception. Can be null. * @see java.lang.Throwable#getMessage */ protected ReferralException(String explanation) { super(explanation); } /** * Constructs a new instance of ReferralException. * All fields are set to null. */ protected ReferralException() { super(); } /** * Retrieves information (such as URLs) related to this referral. * The program may examine or display this information * to the user to determine whether to continue with the referral, * or to determine additional information needs to be supplied in order * to continue with the referral. * * @return Non-null referral information related to this referral. */ public abstract Object getReferralInfo(); /** * Retrieves the context at which to continue the method. * Regardless of whether a referral is encountered directly during a * context operation, or indirectly, for example, during a search * enumeration, the referral exception should provide a context * at which to continue the operation. The referral context is * created using the environment properties of the context * that threw the ReferralException. * *<p> * To continue the operation, the client program should re-invoke * the method using the same arguments as the original invocation. * * @return The non-null context at which to continue the method. * @exception NamingException If a naming exception was encountered. * Call either {@code retryReferral()} or {@code skipReferral()} * to continue processing referrals. */ public abstract Context getReferralContext() throws NamingException; /** * Retrieves the context at which to continue the method using * environment properties. * Regardless of whether a referral is encountered directly during a * context operation, or indirectly, for example, during a search * enumeration, the referral exception should provide a context * at which to continue the operation. *<p> * The referral context is created using {@code env} as its environment * properties. * This method should be used instead of the no-arg overloaded form * when the caller needs to use different environment properties for * the referral context. It might need to do this, for example, when * it needs to supply different authentication information to the referred * server in order to create the referral context. *<p> * To continue the operation, the client program should re-invoke * the method using the same arguments as the original invocation. * * @param env The possibly null environment to use when retrieving the * referral context. If null, no environment properties will be used. * * @return The non-null context at which to continue the method. * @exception NamingException If a naming exception was encountered. * Call either {@code retryReferral()} or {@code skipReferral()} * to continue processing referrals. */ public abstract Context getReferralContext(Hashtable<?, ?> env) throws NamingException; /** * Discards the referral about to be processed. * A call to this method should be followed by a call to * {@code getReferralContext} to allow the processing of * other referrals to continue. * The following code fragment shows a typical usage pattern. * <blockquote><pre> * } catch (ReferralException e) { * if (!shallIFollow(e.getReferralInfo())) { * if (!e.skipReferral()) { * return; * } * } * ctx = e.getReferralContext(); * } * </pre></blockquote> * * @return true If more referral processing is pending; false otherwise. */ public abstract boolean skipReferral(); /** * Retries the referral currently being processed. * A call to this method should be followed by a call to * {@code getReferralContext} to allow the current * referral to be retried. * The following code fragment shows a typical usage pattern. * <blockquote><pre> * } catch (ReferralException e) { * while (true) { * try { * ctx = e.getReferralContext(env); * break; * } catch (NamingException ne) { * if (! shallIRetry()) { * return; * } * // modify environment properties (env), if necessary * e.retryReferral(); * } * } * } * </pre></blockquote> * */ public abstract void retryReferral(); /** * Use serialVersionUID from JNDI 1.1.1 for interoperability */ private static final long serialVersionUID = -2881363844695698876L; }