HibernateModule.java

/*
 * This is eMonocot, a global online biodiversity information resource.
 *
 * Copyright © 2011–2015 The Board of Trustees of the Royal Botanic Gardens, Kew and The University of Oxford
 *
 * eMonocot is free software: you can redistribute it and/or modify it under the terms of the
 * GNU Affero General Public License as published by the Free Software Foundation, either version 3
 * of the License, or (at your option) any later version.
 *
 * eMonocot is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * The complete text of the GNU Affero General Public License is in the source repository as the file
 * ‘COPYING’.  It is also available from <http://www.gnu.org/licenses/>.
 */
package org.emonocot.model.marshall.json.hibernate;

import com.fasterxml.jackson.core.Version;
import com.fasterxml.jackson.databind.AnnotationIntrospector;
import com.fasterxml.jackson.databind.Module;

public class HibernateModule extends Module
{
	private final String NAME = "HibernateModule";

	// Should externalize this somehow
	private final static Version VERSION = new Version(0, 1, 0, null); // 0.1.0

	/**
	 * Enumeration that defines all togglable features this module
	 */
	public enum Feature {
		/**
		 * Whether lazy-loaded object should be forced to be loaded and then serialized
		 * (true); or serialized as nulls (false).
		 *<p>
		 * Default value is false.
		 */
		FORCE_LAZY_LOADING(false),

		/**
		 * Whether @Transient annotation should be checked or not; if true, will consider
		 * @Transient to mean that property is to be ignored; if false annotation will
		 * have no effect.
		 *<p>
		 * Default value is true.
		 *
		 * @since 0.7.0
		 */
		USE_TRANSIENT_ANNOTATION(true)
		;

		final boolean _defaultState;
		final int _mask;

		/**
		 * Method that calculates bit set (flags) of all features that
		 * are enabled by default.
		 */
		public static int collectDefaults()
		{
			int flags = 0;
			for (Feature f : values()) {
				if (f.enabledByDefault()) {
					flags |= f.getMask();
				}
			}
			return flags;
		}

		private Feature(boolean defaultState) {
			_defaultState = defaultState;
			_mask = (1 << ordinal());
		}

		public boolean enabledByDefault() { return _defaultState; }
		public int getMask() { return _mask; }
	}

	protected final static int DEFAULT_FEATURES = Feature.collectDefaults();

	/**
	 * Bit flag composed of bits that indicate which
	 * {@link Feature}s
	 * are enabled.
	 */
	protected int _moduleFeatures = DEFAULT_FEATURES;

	/*
    /**********************************************************************
    /* Life-cycle
    /**********************************************************************
	 */

	public HibernateModule() { }

	@Override public String getModuleName() { return NAME; }
	@Override public Version version() { return VERSION; }

	@Override
	public void setupModule(SetupContext context)
	{
		/* First, append annotation introspector (no need to override, esp.
		 * as we just implement couple of methods)
		 */
		// Then add serializers we need
		AnnotationIntrospector ai = annotationIntrospector();
		if (ai != null) {
			context.appendAnnotationIntrospector(ai);
		}
		context.addSerializers(new HibernateSerializers(_moduleFeatures));
	}

	/**
	 * Method called during {@link #setupModule}, to create {@link AnnotationIntrospector}
	 * to register along with module. If null is returned, no introspector is added.
	 */
	protected AnnotationIntrospector annotationIntrospector() {
		HibernateAnnotationIntrospector ai = new HibernateAnnotationIntrospector();
		ai.setUseTransient(isEnabled(Feature.USE_TRANSIENT_ANNOTATION));
		return ai;
	}

	/*
    /**********************************************************************
    /* Extended API, configuration
    /**********************************************************************
	 */

	public HibernateModule enable(Feature f) {
		_moduleFeatures |= f.getMask();
		return this;
	}

	public HibernateModule disable(Feature f) {
		_moduleFeatures &= ~f.getMask();
		return this;
	}

	public final boolean isEnabled(Feature f) {
		return (_moduleFeatures & f.getMask()) != 0;
	}

	public HibernateModule configure(Feature f, boolean state) {
		if (state) {
			enable(f);
		} else {
			disable(f);
		}
		return this;
	}

}