org.eclipse.osbp.runtime.common/src/org/eclipse/osbp/runtime/common/annotations/FindIdHelper.java

/**
 * Copyright (c) 2011, 2015 - Lunifera GmbH (Gross Enzersdorf, Austria), Loetz GmbH&Co.KG (69115 Heidelberg, Germany)
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0 
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *         Florian Pirchner - Initial implementation
 */
package org.eclipse.osbp.runtime.common.annotations;

import java.beans.BeanInfo;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * The Class FindIdHelper. Can be used for DTOs and Entities.
 */
public class FindIdHelper {

	/** The Constant LOGGER. */
	private static final Logger LOGGER = LoggerFactory.getLogger(FindIdHelper.class);

	/** The infos. */
	private static Map<Class<?>, Info> INFOS = Collections.synchronizedMap(new HashMap<Class<?>, FindIdHelper.Info>());

	/**
	 * Returns the id field. Field annotated with {@link Id}.
	 *
	 * @param clazz
	 *            the clazz
	 * @return the id field
	 */
	public static Field getIdField(Class<?> clazz) {
		Info info = getInfo(clazz);
		return info.getIdField();
	}

	/**
	 * Returns the info for the given class.
	 *
	 * @param clazz
	 *            the clazz
	 * @return the info
	 */
	protected static Info getInfo(Class<?> clazz) {
		Info info = INFOS.get(clazz);
		if (info == null) {
			info = createInfo(clazz);
		}
		return info;
	}

	/**
	 * Returns the id field. Field annotated with {@link Id}.
	 *
	 * @param dto
	 *            the dto
	 * @return the id field
	 */
	public static Object getIdValue(Object dto) {
		Info info = getInfo(dto.getClass());
		Field f = info.getIdField();
		if(f == null) {
			return null;
		}
		f.setAccessible(true);
		try {
			return f.get(dto);
		} catch (IllegalArgumentException | IllegalAccessException e) {
			throw new IllegalStateException(e);
		}
	}

	/**
	 * Returns the field value.
	 *
	 * @param instance
	 *            the instance
	 * @param idProperty
	 *            the id property
	 * @return the value
	 */
	public static Object getValue(Object instance, String idProperty) {
		try {
			BeanInfo beanInfo = Introspector.getBeanInfo(instance.getClass());
			for (PropertyDescriptor pd : beanInfo.getPropertyDescriptors()) {
				if (pd.getName().equals(idProperty)) {
					Method idMethod = pd.getReadMethod();
					return idMethod.invoke(instance);
				}
			}
		} catch (Exception e) {
			LOGGER.error("{}", e);
		}
		return null;
	}

	/**
	 * Returns true, if the given field is a id field.
	 *
	 * @param clazz
	 *            the clazz
	 * @param fieldName
	 *            the field name
	 * @return true, if is id field
	 */
	public static boolean isIdField(Class<?> clazz, String fieldName) {
		Info info = getInfo(clazz);
		return info.getIdField() != null ? info.getIdField().getName().equals(fieldName) : false;
	}

	/**
	 * Creates a new info.
	 *
	 * @param clazz
	 *            the clazz
	 * @return info
	 */
	private static Info createInfo(Class<?> clazz) {
		Info info = new Info();
		applyFieldInfo(clazz, info);

		INFOS.put(clazz, info);

		return info;
	}

	/**
	 * Applies all required field infos to the info object.
	 *
	 * @param clazz
	 *            the clazz
	 * @param info
	 *            the info
	 */
	private static void applyFieldInfo(Class<?> clazz, Info info) {
		try {
			for (Field field : clazz.getDeclaredFields()) {
				if (field.getAnnotation(org.eclipse.osbp.runtime.common.annotations.Id.class) != null
						|| field.getAnnotation(javax.persistence.Id.class) != null) {
					info.idField = field;
					break;
				}
			}

			if (info.idField == null) {
				Class<?> superClass = clazz.getSuperclass();
				if (superClass != null) {
					applyFieldInfo(superClass, info);
				}
			}
		} catch (SecurityException e) {
			LOGGER.error("{}", e);
		}
	}

	/**
	 * The Class Info.
	 */
	private static class Info {

		/** The id field. */
		private Field idField;

		public Field getIdField() {
			return idField;
		}

	}
}