001    /* java.beans.beancontext.BeanContextChild
002       Copyright (C) 1999 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package java.beans.beancontext;
040    
041    import java.beans.PropertyChangeListener;
042    import java.beans.PropertyVetoException;
043    import java.beans.VetoableChangeListener;
044    
045    /**
046     * Beans implement this to get information about the execution environment and
047     * its services and to be placed in the hierarchy.
048     * <P>
049     *
050     * The difference between a <code>BeanContext</code> and a
051     * <code>BeanContextChild</code>, mainly, is that a
052     * <code>BeanContext</code> may be a parent.
053     * <P>
054     *
055     * <code>BeanContextChild</code> instances will be serialized at some
056     * point in their life, but you need to make sure your bean context does
057     * not contain a serializable reference (directly or indirectly) to the
058     * parent <code>BeanContext</code>, to any of the other
059     * <code>BeanContext</code>s in the tree, or to any resources obtained
060     * via the <code>BeanContextServices</code> interface.  One way to do this
061     * is to mark any fields that contain such references as
062     * <code>transient</code>.  Another way is to use a custom serializer.
063     * <P>
064     *
065     * If you do not do this, when the <code>BeanContext</code> is serialized,
066     * all the other <code>BeanContext</code>s and other unnecessary things
067     * will be serialized along with it.
068     * <P>
069     *
070     * Before dying, a <code>BeanContextChild</code> should call
071     * <code>getBeanContext().remove(this)</code> to detach from the
072     * hierarchy and exit cleanly.
073     *
074     * @author John Keiser
075     * @since JDK1.2
076     * @see java.beans.beancontext.BeanContext
077     */
078    
079    public interface BeanContextChild {
080            /**
081             * Set the parent <code>BeanContext</code>.
082             * <P>
083             *
084             * This method is called from <code>BeanContext.add()</code> and
085             * should not be called directly.
086             * <P>
087             *
088             * When this Object is being added to a new BeanContext or moved
089             * from an old one, a non-null value will be passed in.
090             * <P>
091             *
092             * When this Object is being removed from the current
093             * <code>BeanContext</code>, <code>setBeanContext()</code> will
094             * receive the parameter <code>null</code>.
095             * <P>
096             *
097             * When being removed from the current <code>BeanContext</code>,
098             * it is the <code>BeanContextChild</code>'s responsibility to
099             * release all services it has obtained.
100             * <P>
101             *
102             * This change should generate <code>PropertyChangeEvent</code>
103             * and <code>VetoableChangeEvent</code>s with the property name
104             * "beanContext".  If the change is vetoed, it must re-throw the
105             * exception and not change anything.  In this way, the parent
106             * <code>BeanContextChild</code>, who has registered himself with
107             * you, will have a chance to remove this child from its
108             * collection.
109             * <P>
110             *
111             * If the Bean does not wish to change the parent or be removed
112             * from one, it may throw the <code>PropertyVetoException</code>.
113             * If you veto a <code>setBeanContext(null)</code> call, then you
114             * should try your hardest to remedy whatever problem is keeping
115             * you from being removed from the <code>BeanContext</code> so
116             * that you can <em>not</em> veto it the next time.
117             * Otherwise, nasty pathological recursion stuff could occur in
118             * certain situations.
119             * <P>
120             *
121             * If you do veto the change, you must first back out any changes
122             * you made prior to the veto.  Best not to make any such changes
123             * prior to the veto in the first place.
124             * <P>
125             *
126             * This method is called from <code>BeanContext.add()</code> and
127             * should not be called directly.
128             *
129             * @param parent the new parent for the <code>BeanContextChild</code>,
130             *        or <code>null</code> to signify removal from a tree.
131             * @exception PropertyVetoException if the
132             *            <code>BeanContextChild</code> implementor does not
133             *            wish to have its parent changed.
134             */
135            void setBeanContext(BeanContext parent)
136                    throws PropertyVetoException;
137    
138            /**
139             * Get the parent <code>BeanContext</code>.
140             * @return the parent <code>BeanContext</code>.
141             */
142            BeanContext getBeanContext();
143    
144            /**
145             * Add a listener that will be notified when a specific property changes.
146             * @param prop the name of the property to listen on
147             * @param listener the listener to listen on the property.
148             */
149            void addPropertyChangeListener(String prop, PropertyChangeListener listener);
150    
151            /**
152             * Remove a listener to a certain property.
153             * @param prop the name of the property being listened on
154             * @param listener the listener listening on the property.
155             */
156            void removePropertyChangeListener(String prop, PropertyChangeListener listener);
157    
158            /**
159             * Add a listener that will be notified when a specific property
160             * change is requested (a PropertyVetoException may be thrown) as
161             * well as after the change is successfully made.
162             *
163             * @param prop the name of the property to listen on
164             * @param listener the listener to listen on the property.
165             */
166            void addVetoableChangeListener(String prop, VetoableChangeListener listener);
167    
168            /**
169             * Remove a listener to a certain property.
170             * @param prop the name of the property being listened on
171             * @param listener the listener listening on the property.
172             */
173            void removeVetoableChangeListener(String prop, VetoableChangeListener listener);
174    }