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Tools to assist in the reading of configuration/preferences files in
various formats
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.configuration2.builder;
import org.apache.commons.configuration2.event.Event;
import org.apache.commons.configuration2.event.EventListener;
import org.apache.commons.configuration2.reloading.ReloadingController;
import org.apache.commons.configuration2.reloading.ReloadingEvent;
/**
*
* An internally used helper class for adding reloading support to an arbitrary
* {@link ConfigurationBuilder}.
*
*
* This class connects a configuration builder with a
* {@link ReloadingController}. This is done in the following way:
*
* - An instance is registered as listener at a {@code ReloadingController}.
* Whenever the controller indicates that a reload should happen, the associated
* configuration builder's {@link BasicConfigurationBuilder#resetResult()}
* method is called.
* - When the builder fires a {@link ConfigurationBuilderResultCreatedEvent}
* event the reloading controller's reloading state is reset. At that time the
* reload has actually happened, and the controller is prepared to observe new
* changes.
*
*
*
* @since 2.0
*/
final class ReloadingBuilderSupportListener implements EventListener
{
/** Stores the associated configuration builder. */
private final BasicConfigurationBuilder builder;
/** Stores the associated reloading controller. */
private final ReloadingController reloadingController;
/**
* Creates a new instance of {@code ReloadingBuilderSupportListener} and
* initializes it with the associated objects.
*
* @param configBuilder the configuration builder
* @param controller the {@code ReloadingController}
*/
private ReloadingBuilderSupportListener(
final BasicConfigurationBuilder configBuilder,
final ReloadingController controller)
{
builder = configBuilder;
reloadingController = controller;
}
/**
* Creates a new instance of {@code ReloadingBuilderSupportListener} which
* connects the specified {@code ConfigurationBuilder} with the given
* {@code ReloadingController}. Listeners are registered to react on
* notifications and implement a reloading protocol as described in the
* class comment.
*
* @param configBuilder the {@code ConfigurationBuilder}
* @param controller the {@code ReloadingController}
* @return the newly created listener object
*/
public static ReloadingBuilderSupportListener connect(
final BasicConfigurationBuilder configBuilder,
final ReloadingController controller)
{
final ReloadingBuilderSupportListener listener =
new ReloadingBuilderSupportListener(configBuilder, controller);
controller.addEventListener(ReloadingEvent.ANY, listener);
configBuilder
.installEventListener(
ConfigurationBuilderResultCreatedEvent.RESULT_CREATED,
listener);
return listener;
}
/**
* {@inheritDoc} This implementation resets the controller's reloading state
* if an event about a newly created result was received. Otherwise, in case
* of a reloading event, the builder's result object is reset.
*/
@Override
public void onEvent(final Event event)
{
if (ConfigurationBuilderResultCreatedEvent.RESULT_CREATED.equals(event
.getEventType()))
{
reloadingController.resetReloadingState();
}
else
{
builder.resetResult();
}
}
}