java - Connection cannot be cast to oracle.jdbc.OracleConnection

Question

Why java.sql.Connection cannot be cast to oracle.jdbc.OracleConnection in code below?

My main goal is to pass to Oracle connection new user name and save it in 'SESSION' table in for example 'osuser' column because I want to trace in DB user changes and display it in the table.

@Repository
public class AuditLogDAOImpl implements AuditLogDAO {

    @PersistenceContext(unitName="myUnitName")
    EntityManager em;

    @Resource(name = "dataSource")
    DataSource dataSource;

    public void init() {

        try {
            Connection connection = DataSourceUtils.getConnection(dataSource);
            OracleConnection oracleConnection = (OracleConnection) connection; //Here I got cast exception!

            String metrics[] = new String[OracleConnection.END_TO_END_STATE_INDEX_MAX];
            metrics[OracleConnection.END_TO_END_CLIENTID_INDEX] = "my_new_username";

            oracleConnection.setEndToEndMetrics(metrics, (short) 0);

            java.util.Properties props = new java.util.Properties();
            props.put("osuser", "newValue");

            oracleConnection.setClientInfo(props);

        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Here is error log:

10:42:29,251 INFO  [STDOUT] org.jboss.resource.adapter.jdbc.jdk6.WrappedConnectionJDK6@bcc8cb
10:42:51,701 ERROR [STDERR] java.lang.ClassCastException: $Proxy286 cannot be cast to oracle.jdbc.OracleConnection

Generally I have 2 problem in this case:

• why cast from Connection to OracleConnection fails and
• what is the best way to implement my intend (I mean set the new user name to v$session.osuser in Oracle DB?

I work with Oracle 11g, Hibernate (using entity manager), data source via jndi.

Please help, thanks!

EDIT:

After some improvement the problem with casting still exists.

Improvement:

Connection connection = DataSourceUtils.getConnection(dataSource);
connection = ((org.jboss.resource.adapter.jdbc.WrappedConnection)connection).getUnderlyingConnection();
OracleConnection oracleConnection = (OracleConnection) connection;

Error:

java.lang.ClassCastException: $Proxy287 cannot be cast to org.jboss.resource.adapter.jdbc.WrappedConnection

Answer 1

The connection you are retrieving is probably a wrapped connection.

If you really need to get the underlying Oracle connection you should use:

if (connection.isWrapperFor(OracleConnection.class)){
   OracleConnection oracleConnection= connection.unwrap(OracleConnection.class);  
}else{
   // recover, not an oracle connection
}

The isWrapperFor and unwrap methods are available since Java 1.6, and should be meaningfully implemented by the A/S connection wrappers.