libjava/java/beans/beancontext/BeanContextChild.java

   1 /* java.beans.beancontext.BeanContextChild
   2    Copyright (C) 1999 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.beans.beancontext;
  40
  41 import java.beans.PropertyChangeListener;
  42 import java.beans.VetoableChangeListener;
  43 import java.beans.PropertyVetoException;
  44
  45 /**
  46  * Beans implement this to get information about the execution environment and
  47  * its services and to be placed in the hierarchy.
  48  * <P>
  49  *
  50  * The difference between a <code>BeanContext</code> and a
  51  * <code>BeanContextChild</code>, mainly, is that a
  52  * <code>BeanContext</code> may be a parent.
  53  * <P>
  54  *
  55  * <code>BeanContextChild</code> instances will be serialized at some
  56  * point in their life, but you need to make sure your bean context does
  57  * not contain a serializable reference (directly or indirectly) to the
  58  * parent <code>BeanContext</code>, to any of the other
  59  * <code>BeanContext</code>s in the tree, or to any resources obtained
  60  * via the <code>BeanContextServices</code> interface.  One way to do this
  61  * is to mark any fields that contain such references as
  62  * <code>transient</code>.  Another way is to use a custom serializer.
  63  * <P>
  64  *
  65  * If you do not do this, when the <code>BeanContext</code> is serialized,
  66  * all the other <code>BeanContext</code>s and other unnecessary things
  67  * will be serialized along with it.
  68  * <P>
  69  *
  70  * Before dying, a <code>BeanContextChild</code> should call
  71  * <code>getBeanContext().remove(this)</code> to detach from the
  72  * hierarchy and exit cleanly.
  73  *
  74  * @author John Keiser
  75  * @since JDK1.2
  76  * @see java.beans.beancontext.BeanContext
  77  */
  78
  79 public interface BeanContextChild {
  80         /**
  81          * Set the parent <code>BeanContext</code>.
  82          * <P>
  83          *
  84          * This method is called from <code>BeanContext.add()</code> and
  85          * should not be called directly.
  86          * <P>
  87          *
  88          * When this Object is being added to a new BeanContext or moved
  89          * from an old one, a non-null value will be passed in.
  90          * <P>
  91          *
  92          * When this Object is being removed from the current
  93          * <code>BeanContext</code>, <code>setBeanContext()</code> will
  94          * receive the parameter <code>null</code>.
  95          * <P>
  96          *
  97          * When being removed from the current <code>BeanContext</code>,
  98          * it is the <code>BeanContextChild</code>'s responsibility to
  99          * 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 }