org.openvpms.web.component.im.view.IMObjectCollectionViewerFactory.java Source code

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Here is the source code for org.openvpms.web.component.im.view.IMObjectCollectionViewerFactory.java

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/*
 * Version: 1.0
 *
 * The contents of this file are subject to the OpenVPMS License Version
 * 1.0 (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.openvpms.org/license/
 *
 * Software distributed under the License is distributed on an 'AS IS' basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * Copyright 2013 (C) OpenVPMS Ltd. All Rights Reserved.
 */

package org.openvpms.web.component.im.view;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.openvpms.component.business.domain.im.common.IMObject;
import org.openvpms.web.component.im.archetype.ArchetypeHandler;
import org.openvpms.web.component.im.archetype.ArchetypeHandlers;
import org.openvpms.web.component.im.layout.LayoutContext;
import org.openvpms.web.component.property.CollectionProperty;

import java.lang.reflect.Constructor;

/**
 * Factory for {@link IMObjectCollectionViewer}s.
 *
 * @author Tim Anderson
 */
public class IMObjectCollectionViewerFactory {

    /**
     * Viewer implementations.
     */
    private static ArchetypeHandlers<IMObjectCollectionViewer> viewers;

    /**
     * The logger.
     */
    private static final Log log = LogFactory.getLog(IMObjectCollectionViewerFactory.class);

    /**
     * Prevent construction.
     */
    private IMObjectCollectionViewerFactory() {
    }

    /**
     * Creates a new viewer.
     *
     * @param collection the collection to view
     * @param object     the parent of the collection
     * @param context    the layout context. May  be {@code null}
     * @return a viewer for the collection
     */
    public static IMObjectCollectionViewer create(CollectionProperty collection, IMObject object,
            LayoutContext context) {
        IMObjectCollectionViewer result = null;

        String[] shortNames = collection.getArchetypeRange();
        ArchetypeHandler handler = getViewers().getHandler(shortNames);
        if (handler != null) {
            Class type = handler.getType();
            Constructor ctor = getConstructor(type, collection, object, context);
            if (ctor != null) {
                try {
                    result = (IMObjectCollectionViewer) ctor.newInstance(collection, object, context);
                } catch (Throwable throwable) {
                    log.error(throwable, throwable);
                }
            } else {
                log.error("No valid constructor found for class: " + type.getName());
            }
        }
        if (result == null) {
            result = new DefaultIMObjectCollectionViewer(collection, object, context);
        }
        return result;
    }

    /**
     * Returns the Viewers.
     *
     * @return the Viewers
     */
    private static synchronized ArchetypeHandlers<IMObjectCollectionViewer> getViewers() {
        if (viewers == null) {
            viewers = new ArchetypeHandlers<IMObjectCollectionViewer>("IMObjectCollectionViewerFactory.properties",
                    "DefaultIMObjectCollectionViewerFactory.properties", IMObjectCollectionViewer.class);
        }
        return viewers;
    }

    /**
     * Returns a constructor to construct a new viewer.
     *
     * @param type       the Viewer type
     * @param collection the collection property
     * @param object     the parent of the collection
     * @param context    the layout context. May be {@code null}
     * @return a constructor to construct the viewer, or {@code null} if none can be found
     */
    private static Constructor getConstructor(Class type, CollectionProperty collection, IMObject object,
            LayoutContext context) {
        Constructor[] ctors = type.getConstructors();

        for (Constructor ctor : ctors) {
            // check parameters
            Class<?>[] ctorTypes = ctor.getParameterTypes();
            if (ctorTypes.length == 3) {
                Class<?> ctorCollection = ctorTypes[0];
                Class<?> ctorObj = ctorTypes[1];
                Class<?> ctorCtx = ctorTypes[2];

                if (ctorCollection.isAssignableFrom(collection.getClass())
                        && ctorObj.isAssignableFrom(object.getClass())
                        && ((context != null && ctorCtx.isAssignableFrom(context.getClass()))
                                || (context == null && LayoutContext.class.isAssignableFrom(ctorCtx)))) {
                    return ctor;
                }
            }
        }
        return null;
    }

}