You don't setup Fast-Start Failover in the URL. It's something that you setup on the data source using the setFastConnectionFailoverEnabled(true) function call.
Per here
An application enables Fast Connection Failover by calling
setFastConnectionFailoverEnabled(true) on a DataSource instance, before
retrieving any connections from that instance.
You cannot enable Fast Connection Failover when reinitializing a connection
cache. You must enable it before using the OracleDataSource instance.
For example
ods = new OracleDataSource();
...
ods.setFastConnectionFailoverEnabled(true);
Also, it mentions:
FAST CONNECTION FAILOVER PREREQUISITES
1.) The implicit connection cache is enabled. Fast Connection Failover
works in conjunction with the JDBC connection caching mechanism.
This helps applications manage connections to ensure high
availability.
2.) The application uses service names to connect to the database; the
application cannot use service IDs (ORACLE_SID). Use a service name
rather than an SID when setting the OracleDataSource url property.
3.) The underlying database has Release 10 (10.1) or Release 10 (10.2)
Real Application Clusters (RAC) capability. If failover events are
not propagated, connection failover cannot occur.
4.) Oracle Notification Service (ONS) is configured and available on the
node where JDBC is running and on the Oracle RAC. JDBC depends on
ONS to propagate database events from RAC and notify JDBC of them.
If ONS is not correctly set up, then implicit connection cache
creation fails and an ONSException is thrown at the first
getConnection request.
5.) The JVM in which your JDBC instance is running must have
oracle.ons.oraclehome set to point to your ORACLE_HOME. For example:
-Doracle.ons.oraclehome=C:\oracle\product\10.2.0\db_1
6.) Set the FastConnectionFailoverEnabled property before making the
first getConnection request to an OracleDataSource. When Fast
Connection Failover is enabled, the failover applies to all
connections in the connection cache. If your application explicitly
creates a connection cache using the Connection Cache Manager, then
you must first set FastConnectionFailoverEnabled before retrieving
any connections.
7.) The ons.jar must be part of the CLASSPATH for the application.
The ons.jar can be found in the Oracle Client installation.
Edit:
One last thought, if there ever is a failover, you will need to handle the SQLException:
ORA-17008: Closed Connection