public enum Cassandra {
DB;
private Session session;
private Cluster cluster;
private static final Logger LOGGER = LoggerFactory.getLogger(Cassandra.class);
/**
* Connect to the cassandra database based on the connection configuration provided.
* Multiple call to this method will have no effects if a connection is already established
* @param conf the configuration for the connection
*/
public void connect(ConnectionCfg conf) {
if (cluster == null && session == null) {
cluster = Cluster.builder().withPort(conf.getPort()).withCredentials(conf.getUsername(), conf.getPassword()).addContactPoints(conf.getSeeds()).build();
session = cluster.connect(conf.getKeyspace());
}
Metadata metadata = cluster.getMetadata();
LOGGER.info("Connected to cluster: " + metadata.getClusterName() + " with partitioner: " + metadata.getPartitioner());
metadata.getAllHosts().stream().forEach((host) -> {
LOGGER.info("Cassandra datacenter: " + host.getDatacenter() + " | address: " + host.getAddress() + " | rack: " + host.getRack());
});
}
/**
* Invalidate and close the session and connection to the cassandra database
*/
public void shutdown() {
LOGGER.info("Shutting down the whole cassandra cluster");
if (null != session) {
session.close();
}
if (null != cluster) {
cluster.close();
}
}
public Session getSession() {
if (session == null) {
throw new IllegalStateException("No connection initialized");
}
return session;
}
}
Using the Singleton connection
public void cassandra() throws Exception {
Cassandra.DB.connect();
Cassandra.DB.getSession().execute(/* CQL | Statement | PreparedStatement */)
Cassandra.DB.close();
}