sql/storm-sql-runtime/src/jvm/org/apache/storm/sql/runtime/DataSourcesRegistry.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.storm.sql.runtime;

import java.net.URI;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.ServiceLoader;

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

public class DataSourcesRegistry {
    private static final Logger LOG = LoggerFactory.getLogger(
            DataSourcesRegistry.class);
    private static final Map<String, DataSourcesProvider> providers;

    static {
        providers = new HashMap<>();
        ServiceLoader<DataSourcesProvider> loader = ServiceLoader.load(
                DataSourcesProvider.class);
        for (DataSourcesProvider p : loader) {
            LOG.info("Registering scheme {} with {}", p.scheme(), p);
            providers.put(p.scheme(), p);
        }
    }

    private DataSourcesRegistry() {
    }

    /**
     * Construct a streams data source.
     * @param uri data source uri
     * @param inputFormatClass input format class
     * @param outputFormatClass output format class
     * @param properties Properties
     * @param fields fields info list
     * @return StreamsDataSource object
     */
    public static ISqlStreamsDataSource constructStreamsDataSource(
            URI uri, String inputFormatClass, String outputFormatClass,
            Properties properties, List<FieldInfo> fields) {
        DataSourcesProvider provider = providers.get(uri.getScheme());
        if (provider == null) {
            return null;
        }

        return provider.constructStreams(uri, inputFormatClass, outputFormatClass, properties, fields);
    }

    /**
     * Allow unit tests to inject data sources.
     */
    public static Map<String, DataSourcesProvider> providerMap() {
        return providers;
    }
}