SpiDataModelSourceProvider.java

/**
 * Copyright 2011-2017 Asakusa Framework Team.
 *
 * 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
 *
 *     http://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 com.asakusafw.testdriver.core;

import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import java.util.ServiceLoader;

/**
 * Composition of registered {@link DataModelSourceProvider} as {@link ServiceLoader services}.
 * @since 0.2.3
 */
public class SpiDataModelSourceProvider implements DataModelSourceProvider {

    private final List<DataModelSourceProvider> elements;

    /**
     * Creates a new instance.
     * @param serviceClassLoader the class loader to load the registered services
     * @throws IllegalArgumentException if some parameters were {@code null}
     */
    @SuppressWarnings("deprecation")
    public SpiDataModelSourceProvider(ClassLoader serviceClassLoader) {
        if (serviceClassLoader == null) {
            throw new IllegalArgumentException("serviceClassLoader must not be null"); //$NON-NLS-1$
        }
        this.elements = new ArrayList<>();
        this.elements.addAll(Util.loadService(SourceProvider.class, serviceClassLoader));
        this.elements.addAll(Util.loadService(DataModelSourceProvider.class, serviceClassLoader));
    }

    @Override
    public <T> DataModelSource open(
            DataModelDefinition<T> definition,
            URI source,
            TestContext context) throws IOException {
        for (DataModelSourceProvider service : elements) {
            DataModelSource result = service.open(definition, source, context);
            if (result != null) {
                return result;
            }
        }
        return null;
    }
}