If your tables in Oracle are not big or you need to perform oracle data extract in test environment, then all suggestions above should work.

If you large tables (millions of rows or even terabytes of data), blob type, chained rows,.. etc, you may want consider third party tool. Especially if you need to unload data quickly from production server with no adding cpu overhead. I would suggest wisdomforce Fastreader www.wisdomforce.com .

Fastreader is really fast, support all features that production DBA need and also generates loaders for not just Oracle, but also DB2, MySQL, SQL Server. This is very convinient for automating migrate process.