Type 4 is the best type of Jdbc
JDBC Net pure Java Driver
A native-protocol pure Java driver converts JDBC technology into the network protocol.
It allows a direct call from the client machine to the DBMS server and
It is the fastest JDBC driver.
Type 1 and Type 3 drivers will be slower than Type 2 drivers (the database calls are make at least three translations versus two),
and Type 4 drivers are the fastest (only one translation).
For more read more in details to visit...http://www.roseindia.net/jdbc/jdbc-driver-and-its-types.shtml