com.mmnaseri.dragonfly.events.CallbackResolver.java Source code

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Here is the source code for com.mmnaseri.dragonfly.events.CallbackResolver.java

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/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2013 Milad Naseri.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package com.mmnaseri.dragonfly.events;

import com.mmnaseri.dragonfly.metadata.TableMetadataContext;
import com.mmnaseri.dragonfly.metadata.TableMetadataContextPostProcessor;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import javax.persistence.EntityListeners;
import java.util.Collection;
import java.util.HashSet;

/**
 * @author Milad Naseri (mmnaseri@programmer.net)
 * @since 1.0 (2013/10/11, 12:11)
 */
public class CallbackResolver implements TableMetadataContextPostProcessor, EventHandlerContextPostProcessor {

    private static final Log log = LogFactory.getLog(CallbackResolver.class);
    private final Collection<DataAccessEventHandler> eventHandlers = new HashSet<DataAccessEventHandler>();
    private boolean handlersFound = false;
    private boolean contextFound = false;
    private boolean contextProcessed = false;
    private EventHandlerContext eventHandlerContext;

    public CallbackResolver() {
        log.info("Initializing event handler resolver ...");
    }

    @Override
    public synchronized void postProcessMetadataContext(TableMetadataContext tableMetadataContext) {
        log.info("Looking up entity callbacks");
        final Collection<Class<?>> entityTypes = tableMetadataContext.getEntityTypes();
        eventHandlers.add(new EntityEventCallback());
        for (Class<?> entityType : entityTypes) {
            if (entityType.isAnnotationPresent(EntityListeners.class)) {
                final EntityListeners listeners = entityType.getAnnotation(EntityListeners.class);
                for (final Class type : listeners.value()) {
                    log.info("Registering external callback: " + type);
                    eventHandlers.add(new EntityEventCallback(entityType, type));
                }
            }
        }
        handlersFound = true;
        if (contextFound) {
            registerHandlers();
        }
    }

    @Override
    public synchronized void postProcessEventHandlerContext(EventHandlerContext eventHandlerContext) {
        this.eventHandlerContext = eventHandlerContext;
        contextFound = true;
        if (handlersFound) {
            registerHandlers();
        }
    }

    private synchronized void registerHandlers() {
        if (contextProcessed) {
            return;
        }
        contextProcessed = true;
        if (!contextFound || !handlersFound) {
            throw new IllegalStateException();
        }
        if (eventHandlers.isEmpty()) {
            log.info("No entity-specific event handlers were found.");
            return;
        }
        log.info("Registering event handlers ...");
        for (DataAccessEventHandler eventHandler : eventHandlers) {
            eventHandlerContext.addHandler(eventHandler);
        }
    }

}