CassandraProducer.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.camel.component.cassandra;

import java.util.Collection;

import com.datastax.driver.core.PreparedStatement;
import com.datastax.driver.core.RegularStatement;
import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.Session;
import org.apache.camel.Exchange;
import org.apache.camel.Message;
import org.apache.camel.impl.DefaultProducer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static org.apache.camel.utils.cassandra.CassandraUtils.isEmpty;

/**
 * Cassandra 2 CQL3 producer.
 * <dl>
 * <dt>In Message</dt>
 * <dd>Bound parameters: Collection of Objects, Array of Objects, Simple Object<dd>
 * <dt>Out Message</dt>
 * <dd>List of all Rows<dd>
 * <dl>
 */
public class CassandraProducer extends DefaultProducer {

    private static final Logger LOG = LoggerFactory.getLogger(CassandraProducer.class);
    private PreparedStatement preparedStatement;

    public CassandraProducer(CassandraEndpoint endpoint) {
        super(endpoint);
    }

    @Override
    protected void doStart() throws Exception {
        super.doStart();
        if (isPrepareStatements() && getEndpoint().getCql() != null) {
            this.preparedStatement = getEndpoint().prepareStatement();
        }
    }

    @Override
    protected void doStop() throws Exception {
        this.preparedStatement = null;
        super.doStop();
    }

    @Override
    public CassandraEndpoint getEndpoint() {
        return (CassandraEndpoint) super.getEndpoint();
    }

    public boolean isPrepareStatements() {
        return getEndpoint().isPrepareStatements();
    }

    private Object[] getCqlParams(Message message) {
        Object cqlParamsObj = message.getBody();
        Object[] cqlParams;
        final Class<Object[]> objectArrayClazz = Object[].class;
        if (cqlParamsObj == null) {
            cqlParams = null;
        } else if (objectArrayClazz.isInstance(cqlParamsObj)) {
            cqlParams = objectArrayClazz.cast(cqlParamsObj);
        } else if (cqlParamsObj instanceof Collection) {
            final Collection cqlParamsColl = (Collection) cqlParamsObj;
            cqlParams = cqlParamsColl.toArray();
        } else {
            cqlParams = new Object[]{cqlParamsObj};
        }
        return cqlParams;
    }

    /**
     * Execute CQL query using incoming message body has statement parameters.
     */
    private ResultSet execute(Message message) {
        Object messageCql = message.getHeader(CassandraConstants.CQL_QUERY);
        // Convert Empty string to null
        if (messageCql instanceof String && ((String) messageCql).isEmpty()) {
            messageCql = null;
        }
        Object[] cqlParams = getCqlParams(message);

        ResultSet resultSet;
        Session session = getEndpoint().getSessionHolder().getSession();
        if (isPrepareStatements()) {
            resultSet = executePreparedStatement(session, messageCql, cqlParams);
        } else {
            resultSet = executeStatement(session, messageCql, cqlParams);
        }
        return resultSet;
    }

    /**
     * Execute CQL as PreparedStatement
     */
    private ResultSet executePreparedStatement(Session session, Object messageCql, Object[] cqlParams) {
        ResultSet resultSet;
        PreparedStatement lPreparedStatement;
        if (messageCql == null) {
            // URI CQL
            lPreparedStatement = this.preparedStatement;
        } else if (messageCql instanceof String) {
            // Message CQL
            lPreparedStatement = getEndpoint().prepareStatement((String) messageCql);
        } else if (messageCql instanceof RegularStatement) {
            // Message Statement
            lPreparedStatement = getEndpoint().getSession().prepare((RegularStatement) messageCql);
        } else {
            throw new IllegalArgumentException("Invalid " + CassandraConstants.CQL_QUERY + " header");
        }
        if (isEmpty(cqlParams)) {
            resultSet = session.execute(lPreparedStatement.bind());
        } else {
            resultSet = session.execute(lPreparedStatement.bind(cqlParams));
        }
        return resultSet;
    }

    /**
     * Execute CQL as is
     */
    private ResultSet executeStatement(Session session, Object messageCql, Object[] cqlParams) {
        ResultSet resultSet;
        String cql = null;
        RegularStatement statement = null;
        if (messageCql == null) {
            // URI CQL
            cql = getEndpoint().getCql();
        } else if (messageCql instanceof String) {
            // Message CQL
            cql = (String) messageCql;
        } else if (messageCql instanceof RegularStatement) {
            // Message Statement
            statement = (RegularStatement) messageCql;
        } else {
            throw new IllegalArgumentException("Invalid " + CassandraConstants.CQL_QUERY + " header");
        }
        if (statement != null) {
            resultSet = session.execute(statement);
        } else if (isEmpty(cqlParams)) {
            resultSet = session.execute(cql);
        } else {
            resultSet = session.execute(cql, cqlParams);
        }
        return resultSet;
    }

    public void process(Exchange exchange) throws Exception {
        // copy the header of in message to the out message
        exchange.getOut().copyFrom(exchange.getIn());

        ResultSet resultSet = execute(exchange.getIn());
        getEndpoint().fillMessage(resultSet, exchange.getOut());
    }

}