Source for java.beans.beancontext.BeanContextChild

   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., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 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.PropertyVetoException;
  43: import java.beans.VetoableChangeListener;
  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: }