173 lines
5.9 KiB
Java
173 lines
5.9 KiB
Java
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* $Header:$
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*/
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package org.apache.beehive.controls.runtime.bean;
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import java.beans.beancontext.BeanContextServiceProvider;
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import java.beans.beancontext.BeanContextServices;
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import java.lang.reflect.Method;
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import java.util.Iterator;
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import java.util.Vector;
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import org.apache.beehive.controls.api.context.ResourceContext;
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/**
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* The ResourceContextImpl class provides an implementation of the ResourceContext service,
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* as well as a simple singleton provider that can be used to obtain new instances.
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*/
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public class ResourceContextImpl implements ResourceContext, InvokeListener
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{
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/**
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* The ResourceContextProvider inner class acts as a single BeanContext service
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* provider for the ResourceContext service class.
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*/
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private static class ResourceContextProvider
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implements BeanContextServiceProvider {
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//
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// BeanContextServiceProvider.getService()
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//
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public Object getService(BeanContextServices bcs, Object requestor, Class serviceClass, Object serviceSelector)
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{
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//
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// There is an implied contract between ControlContainerContext and ControlBean
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// classes required to implement the resource management contract. This cannot
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// be supported for any generic BeanContextChild class.
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//
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if (requestor instanceof ControlBean)
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{
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return new ResourceContextImpl((ControlContainerContext)bcs, (ControlBean)requestor);
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}
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return null;
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}
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//
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// BeanContextServiceProvider.releaseService()
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//
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public void releaseService(BeanContextServices bcs, Object requestor, Object service)
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{
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return; // Should not happen, service is never unregistered
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}
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//
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// BeanContextServiceProvider.getContextServiceSelectors()
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//
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public Iterator getCurrentServiceSelectors(BeanContextServices bcs, Class serviceClass)
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{
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return null; // no selectors
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}
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}
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/**
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* A singleton instance of the ResourceContextProvider class is what will be registered
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* on all ControlContainerContext instances. The provider can be a singleton because it is
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* completely stateless and thread-safe.
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*/
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static private ResourceContextProvider _theProvider = new ResourceContextProvider();
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/**
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* Returns the ResourceContextProvider used to create new ResourceContext instances
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*/
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static /* package */ ResourceContextProvider getProvider() { return _theProvider; }
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/**
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* Constructs a new ResourceContext service implementation to manage resources for
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* a target ControlBean within a specific ControlContainerContext
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*/
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public ResourceContextImpl(ControlContainerContext containerContext, ControlBean bean)
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{
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_containerContext = containerContext;
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_bean = bean;
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//
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// Register to receive invocation notifications from the target bean
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//
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_bean.addInvokeListener(this);
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}
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/**
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* Implements the InvokeListener.preInvoke method. This hook will be called before the
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* managed beans' operations are invoked
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*/
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public void preInvoke(Method m, Object [] args)
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{
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if (!_hasAcquired)
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acquire();
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}
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/**
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* Implements the InvokeListener.postInvoke method.
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*/
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public void postInvoke(Object retval, Throwable t) {}
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// ResourceContext.acquire()
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public void acquire()
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{
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if (_hasAcquired)
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return;
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// Deliver the onAcquire event to registered listeners
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for (ResourceEvents resourceListener : _listeners)
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resourceListener.onAcquire();
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// Register this ResourceContext with associated container context
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_containerContext.addResourceContext(this, _bean);
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// Set the flag to indicate resources have been acquired.
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_hasAcquired = true;
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}
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// ResourceContext.release()
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public void release()
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{
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if (!_hasAcquired)
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return;
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// Deliver the onRelease event to the registered listeners
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for (ResourceEvents resourceListener : _listeners)
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resourceListener.onRelease();
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// Unregister this ResourceContext with associated container context
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_containerContext.removeResourceContext(this, _bean);
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// Reset the flag to indicate resources have been released.
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_hasAcquired = false;
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}
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// ResourceContext.hasResources()
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public boolean hasResources() { return _hasAcquired; }
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// ResourceContext.addResourceEventsListener
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public void addResourceEventsListener(ResourceEvents resourceListener)
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{
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_listeners.add(resourceListener);
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}
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// ResourceContext.removeResourceEventsListener
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public void removeResourceEventsListener(ResourceEvents resourceListener)
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{
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_listeners.remove(resourceListener);
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}
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private Vector<ResourceEvents> _listeners = new Vector<ResourceEvents>();
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private boolean _hasAcquired = false;
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private ControlContainerContext _containerContext;
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private ControlBean _bean;
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}
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