/*
 * Copyright 2002-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory.serviceloader;

import java.util.Iterator;
import java.util.ServiceLoader;

import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.lang.Nullable;

/**
 * {@link org.springframework.beans.factory.FactoryBean} that exposes the
 * 'primary' service for the configured service class, obtained through
 * the JDK 1.6 {@link java.util.ServiceLoader} facility.
 *
 * @author Juergen Hoeller
 * @since 2.5
 * @see java.util.ServiceLoader
 */
public class ServiceFactoryBean extends AbstractServiceLoaderBasedFactoryBean implements BeanClassLoaderAware {

	@Override
	protected Object getObjectToExpose(ServiceLoader<?> serviceLoader) {
		Iterator<?> it = serviceLoader.iterator();
		if (!it.hasNext()) {
			throw new IllegalStateException(
					"ServiceLoader could not find service for type [" + getServiceType() + "]");
		}
		return it.next();
	}

	@Override
	@Nullable
	public Class<?> getObjectType() {
		return getServiceType();
	}

}
