ReloadingBuilderSupportListener.java
- /*
- * 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;
- /**
- * <p>
- * An internally used helper class for adding reloading support to an arbitrary {@link ConfigurationBuilder}.
- * </p>
- * <p>
- * This class connects a configuration builder with a {@link ReloadingController}. This is done in the following way:
- * <ul>
- * <li>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.</li>
- * <li>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.</li>
- * </ul>
- * </p>
- *
- * @since 2.0
- */
- final class ReloadingBuilderSupportListener implements EventListener<Event> {
- /**
- * 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;
- }
- /** 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;
- }
- /**
- * {@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();
- }
- }
- }