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273 lines
10 KiB
Java
273 lines
10 KiB
Java
/* java.beans.beancontext.BeanContext
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Copyright (C) 1999 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.beans.beancontext;
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import java.util.Collection;
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import java.beans.Visibility;
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import java.beans.DesignMode;
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import java.net.URL;
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import java.io.InputStream;
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import java.io.IOException;
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/**
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* Acts as a container for sub-beans and as a sub-bean,
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* so that an entire hierarchy of beans can be made up of
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* <code>BeanContext</code>s.
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* <P>
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*
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* Since I can't sprinkle the <code>Collections</code> interface
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* documentation with special information for <code>BeanContext</code>
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* implementors, I'll have to document special requirements for
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* implementors of those functions here.
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* <P>
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*
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* <code><strong>add()</strong></code> or <code>addAll()</code>:
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* <br>
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* <OL>
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* <LI>
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* May add any <code>Object</code> into the hierarchy as well as a
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* <code>BeanContextChild</code>, <code>BeanContext</code> or
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* <code>BeanContextProxy</code> object.
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* This way, any Bean can be in the hierarchy.
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* </LI>
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* <LI>
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* Must synchronize on <code>BeanContext.globalHierarchyLock</code>.
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* </LI>
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* <LI>
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* Don't add the <code>Object</code> if it's already there (only once
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* per <code>BeanContext</code>).
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* </LI>
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* <LI>
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* If it is a <code>BeanContextChild</code> implementor, call
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* <code>setBeanContext()</code> on it. If it's a
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* <code>BeanContextProxy</code> implementor, call
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* <code>getBeanContextProxy().setBeanContext()</code> on it.
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* If <code>setBeanContext()</code> vetoes the change, back out
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* all changes so far and throw <code>IllegalStateException</code>.
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* </LI>
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* <LI>
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* If it (or its proxy) implements <code>Visibility</code>, call
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* <code>dontUseGui()</code> or <code>okToUseGui()</code> on it,
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* depending on whether you (the <code>BeanContext</code>) feel like
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* allowing it to use the GUI or not.
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* </LI>
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* <LI>
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* If it implements <code>BeanContextChild</code> or
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* <code>BeanContextProxy</code>, register yourself (the
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* <code>BeanContext</code>) as both a
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* <code>PropertyChangeListener</code> and
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* <code>VetoableChangeListener</code> on the "beanContext"
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* property (it may also add itself on any other properties it wishes
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* to).
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* </LI>
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* <LI>
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* If it is a listener or event source that you (the
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* <code>BeanContext</code>) are interested in, you may register
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* yourself to it or register it to you.
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* </LI>
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* <LI>
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* Fire a <code>java.beans.beancontext.BeanContextMembershipEvent</code>
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* before exiting. <code>addAll()</code> should wait until everything
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* is done changing before firing the event (or events) so that if a
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* failure occurs, the backing-out process can proceed without any
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* events being fired at all.
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* </LI>
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* </OL>
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* <P>
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*
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* <code><strong>remove()</strong></code> or <code>removeAll()</code>:
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* <br>
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* <OL>
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* <LI>
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* Must synchronize on <code>BeanContext.globalHierarchyLock</code>.
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* </LI>
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* <LI>
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* If the specified <code>Object</code> is not a child of this
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* <code>BeanContext</code>, just exit without performing any actions.
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* </LI>
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* <LI>
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* Remove the <code>Object</code> from your collection of children.
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* </LI>
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* <LI>
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* If it is a <code>BeanContextChild</code> implementor, call
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* <code>setBeanContext(null)</code> on it. If it's a
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* <code>BeanContextProxy</code> implementor, call
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* <code>getBeanContextProxy().setBeanContext(null)</code> on it.
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* If <code>setBeanContext()</code> vetoes the change, back out
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* all changes so far and throw <code>IllegalStateException</code>.
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* </LI>
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* <LI>
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* If you registered the <code>Object</code> to listen to you or
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* registered yourself as a listener on the <code>Object</code> during
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* <code>add()</code> or <code>addAll()</code>, undo the registration
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* bycalling the appropriate <code>removeListener()</code> method.
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* </LI>
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* <LI>
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* Fire a <code>java.beans.beancontext.BeanContextMembershipEvent</code>
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* before exiting. <code>removeAll()</code> should wait until
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* everything is done changing before firing the event (or events) so
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* that if a failure occurs, the backing-out process can proceed
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* without any events being fired at all.
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* </LI>
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* </OL>
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* <P>
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*
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* <code>addAll()</code>, <code>removeAll()</code>,
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* <code>retainAll()</code> and <code>clear()</code> do not need to be
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* implemented, but may be if so desired.
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* <P>
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*
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* Similarly, <code>Visibility</code> and <code>DesignMode</code> methods
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* should propagate changed values to children that implement interfaces
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* of the same name.
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* <P>
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*
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* A hierarchy of beans is mainly useful so that different sets of beans
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* can be established, each with their own set of resources.
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*
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* @author John Keiser
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* @since JDK1.2
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*/
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public interface BeanContext
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extends Collection, BeanContextChild, Visibility, DesignMode {
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/**
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* The global lock on changing any BeanContext hierarchy.
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* It kinda sucks that there is only one lock, since there can be
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* multiple hierarchies. Oh well, I didn't design, I just code.
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* <P>
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*
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* Methods that must (or do) synchronize on the global lock:
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* <BR>
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* <UL>
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* <LI>
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* Implementors of <CODE>BeanContext.add()</CODE> and <code>addAll()</code>
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* </LI>
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* </UL>
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* @fixme fill in the rest of the methods which use the global lock.
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*/
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public static final Object globalHierarchyLock = new Object();
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/**
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* Instantiate a Bean using this Bean's <code>ClassLoader</code>
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* and this <code>BeanContext</code> as the parent.
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* <P>
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*
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* This method exists mainly so that <code>BeanContext</code>
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* implementations can perform extra actions on Beans that are
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* created within them.
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*
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* @param beanName the name of the bean to instantiate
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* @return the created Bean
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*
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* @see java.beans.Beans#instantiate(java.lang.ClassLoader,java.lang.String)
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* @see java.beans.Beans#instantiate(java.lang.ClassLoader,java.lang.String,java.lang.BeanContext)
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* @exception IOException if there is an I/O problem during
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* instantiation.
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* @exception ClassNotFoundException if a serialized Bean's class
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* is not found.
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*/
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public Object instantiateChild(String beanName)
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throws IOException,
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ClassNotFoundException;
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/**
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* Get a resource. The <code>BeanContext</code> will typically
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* call <code>ClassLoader.getResource()</code>, but may do it any
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* way it wants to. This allows a <code>BeanContext</code> to
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* have its own set of resources separate from the rest of the
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* system.
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* <P>
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*
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* Beans should call this method on their parent rather than the
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* associated <code>ClassLoader</code> method.
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* <P>
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*
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* I am assuming, but am not entirely sure, that if a
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* <code>BeanContext</code> cannot find a resource, its
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* responsibility is to call the <code>getResource</code> method
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* of its parent <code>BeanContext</code>.
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*
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* @return a URL to the requested resource.
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* @param resourceName the name of the resource requested.
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* @param requestor a reference to the child requesting the resource.
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* @see java.lang.ClassLoader#getResource(java.lang.String)
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*/
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public URL getResource(String resourceName, BeanContextChild requestor);
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/**
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* Get a resource as a stream. The <code>BeanContext</code> will
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* typically call <code>ClassLoader.getResourceAsStream()</code>,
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* but may do it any way it wants to. This allows a
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* <code>BeanContext</code>'s children to have their own set of
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* resources separate from the rest of the system.
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* <P>
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*
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* Beans should call this method on their parent rather than the
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* associated <code>ClassLoader</code> method.
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* <P>
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*
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* I am assuming, but am not entirely sure, that if a
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* <code>BeanContext</code> cannot find a resource, its
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* responsibility is to call the <code>getResourceAsStream</code>
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* method of its parent <code>BeanContext</code>.
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*
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* @return the requested resource as a stream.
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* @param resourceName the name of the resource requested.
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* @param requestor a reference to the child requesting the resource.
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* @see java.lang.ClassLoader#getResourceAsStream(java.lang.String)
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*/
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public InputStream getResourceAsStream(String resourceName, BeanContextChild requestor);
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/**
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* Add a listener on changes to the membership of this
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* <code>BeanContext</code> object.
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* @param listener the listener to add.
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*/
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public void addBeanContextMembershipListener(BeanContextMembershipListener listener);
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/**
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* Remove a listener on changes to the membership of this
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* <code>BeanContext</code> object.
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* @param listener the listener to remove.
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*/
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public void removeBeanContextMembershipListener(BeanContextMembershipListener listener);
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}
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