JndiSqlMap.java

/*
 * Copyright 2013, 2014 Deutsche Nationalbibliothek
 *
 * 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 org.culturegraph.mf.metamorph.maps;

import java.io.Closeable;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;

import org.culturegraph.mf.metamorph.api.MorphExecutionException;
import org.culturegraph.mf.metamorph.api.helpers.AbstractReadOnlyMap;

/**
 * A map which queries an sql database provided as jndi
 * resource.
 *
 * @author Daniel Schäfer
 *
 */
public final class JndiSqlMap extends AbstractReadOnlyMap<String, String>
		implements Closeable {

	private DataSource datasource;
	private String query;

	public void setDatasource(final String name) {
		try {
			this.datasource = (DataSource) new InitialContext().lookup(name);
		} catch (final NamingException e) {
			throw new MorphExecutionException(
					"jndisqlmap: lookup of data source failed", e);
		}
	}

	public void setQuery(final String query) {
		this.query = query;
	}

	@Override
	public String get(final Object key) {
		String resultString = null;
		try(
				final Connection connection = datasource.getConnection();
				final PreparedStatement statement =
						connection.prepareStatement(query);
		) {
			statement.setString(1, key.toString());
			try(final ResultSet resultSet = statement.executeQuery()) {
				if (resultSet.first()) {
					resultString = resultSet.getString(1);
				}
			}
		} catch (final SQLException e) {
			throw new MorphExecutionException(
					"jndisqlmap: execution of sql query failed", e);
		}
		return resultString;
	}

	@Override
	public void close() throws IOException {
		// Nothing to do
	}

}