platform/sensinact-core/src/main/java/org/eclipse/sensinact/gateway/core/method/ReflectionAccessMethodExecutor.java

/*
* Copyright (c) 2020 Kentyou.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
*    Kentyou - initial API and implementation
 */
package org.eclipse.sensinact.gateway.core.method;

import java.lang.reflect.Method;

import org.json.JSONObject;

/**
 * Extended {@link AbstractAccessMethodExecutor} implementation referring to a
 * java {@link Method}
 * 
 * @author <a href="mailto:christophe.munilla@cea.fr">Christophe Munilla</a>
 */
public class ReflectionAccessMethodExecutor extends AbstractAccessMethodExecutor {

	private final Method method;
	private Object target;

	/**
	 * Constructor
	 * 
	 * @throws InvalidReflectiveExecutorException
	 */
	public ReflectionAccessMethodExecutor(Object target, Method method) throws InvalidReflectiveExecutorException {
		super();
		if (!method.getDeclaringClass().isAssignableFrom(target.getClass())) {
			throw new InvalidReflectiveExecutorException("Incompatible method and target types");
		}
		if (!JSONObject.class.isAssignableFrom((Class<?>) method.getGenericReturnType())
				&& !Void.class.isAssignableFrom((Class<?>) method.getGenericReturnType())) {
			throw new InvalidReflectiveExecutorException("Incompatible returned type : JSONObject or Void expected");
		}
		this.method = method;
		this.target = target;
	}

	/**
	 * Executes this extended {@link Executable} if the parameters wrapped by the
	 * {@link AccessMethodResponseBuilder} argument comply the registered
	 * constraints
	 * 
	 * @param parameter
	 *            the {@link AccessMethodResponseBuilder} parameterizing the
	 *            execution, in which to stack the JSON formated result object of
	 *            the execution
	 * 
	 * @throws Exception
	 */
	protected void doExecute(AccessMethodResponseBuilder responseBuilder) throws Exception {
		Object result = method.invoke(target, responseBuilder.getParameters());

		if (result != null && responseBuilder.getComponentType().isAssignableFrom(result.getClass())) {
			responseBuilder.push(result);
		}
	}
}