io.klerch.alexa.tellask.util.factory.AlexaLaunchHandlerFactory Maven / Gradle / Ivy

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This SDK is an extension to the Alexa Skills SDK for Java. It provides a framework for handling speechlet requests with multi-variant utterances organized in YAML files that make it easy to create localized skills. This SDK also lets you build your skill in declarative style and avoids a lot of boilerplate code.

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/**
 * Created by Kay Lerch (https://twitter.com/KayLerch)
 *
 * Contribute to https://github.com/KayLerch/alexa-skills-kit-tellask-java
 *
 * Attached license applies.
 * This source is licensed under GNU GENERAL PUBLIC LICENSE Version 3 as of 29 June 2007
 */
package io.klerch.alexa.tellask.util.factory;

import io.klerch.alexa.tellask.schema.AlexaLaunchHandler;
import org.apache.log4j.Logger;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Optional;

/**
 * Constructs the AlexaLaunchHandler which is tagged with the AlexaLaunchListener-annotation.
 */
public class AlexaLaunchHandlerFactory {
    public static final String FACTORY_PACKAGE = AlexaLaunchHandlerFactory.class.getPackage().getName();
    public static final String FACTORY_CLASS_NAME = AlexaLaunchHandlerFactory.class.getSimpleName() + "Impl";
    public static final String FACTORY_METHOD_NAME = "createHandler";

    private static final Logger LOG = Logger.getLogger(AlexaLaunchHandlerFactory.class);

    private AlexaLaunchHandlerFactory() {
        // hides the implicit public constructor
    }

    /**
     * Constructs the AlexaLaunchHandler which is tagged with the AlexaLaunchListener-annotation.
     * If more than one of those handlers were found it will only return the first one found as
     * your skill only needs one of them.
     * @return AlexaLaunchHandler to handle launch events of your skill
     */
    @SuppressWarnings("unchecked")
    public static Optional createHandler() {
        try {
            final Class factoryImpl = Class.forName(FACTORY_PACKAGE + "." + FACTORY_CLASS_NAME);
            final Method method = factoryImpl.getMethod(FACTORY_METHOD_NAME);
            final Object handler = method.invoke(null);
            return handler != null ? Optional.of((AlexaLaunchHandler) handler) : Optional.empty();
        } catch (ClassNotFoundException | NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
            LOG.error("Could not access generated factory to obtain launch handlers likely because there is no valid launch handler in your project at all.", e);
            return Optional.empty();
        }
    }
}