1 /*
   2  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.xml.internal.bind;
  27 
  28 import javax.xml.bind.Marshaller;
  29 
  30 /**
  31  * Optional interface that can be implemented by JAXB-bound objects
  32  * to handle cycles in the object graph.
  33  *
  34  * <p>
  35  * As discussed in <a href="https://jaxb.dev.java.net/guide/Mapping_cyclic_references_to_XML.html">
  36  * the users' guide</a>, normally a cycle in the object graph causes the marshaller to report an error,
  37  * and when an error is found, the JAXB RI recovers by cutting the cycle arbitrarily.
  38  * This is not always a desired behavior.
  39  *
  40  * <p>
  41  * Implementing this interface allows user application to change this behavior.
  42  * Also see <a href="http://forums.java.net/jive/thread.jspa?threadID=13670">this related discussion</a>.
  43  *
  44  * @since JAXB 2.1 EA2
  45  * @author Kohsuke Kawaguchi
  46  */
  47 public interface CycleRecoverable {
  48     /**
  49      * Called when a cycle is detected by the JAXB RI marshaller
  50      * to nominate a new object to be marshalled instead.
  51      *
  52      * @param context
  53      *      This object is provided by the JAXB RI to inform
  54      *      the object about the marshalling process that's going on.
  55      *
  56      *
  57      * @return
  58      *      the object to be marshalled instead of <tt>this</tt> object.
  59      *      Or return null to indicate that the JAXB RI should behave
  60      *      just like when your object does not implement {@link CycleRecoverable}
  61      *      (IOW, cut the cycle arbitrarily and try to go on.)
  62      */
  63     Object onCycleDetected(Context context);
  64 
  65     /**
  66      * This interface is implemented by the JAXB RI to provide
  67      * information about the on-going marshalling process.
  68      *
  69      * <p>
  70      * We may add more methods in the future, so please do not
  71      * implement this interface in your application.
  72      */
  73     public interface Context {
  74         /**
  75          * Returns the marshaller object that's doing the marshalling.
  76          *
  77          * @return
  78          *      always non-null.
  79          */
  80         Marshaller getMarshaller();
  81     }
  82 }