To compile the driver simply run ant in the top level
directory. The compiled driver will be placed in jars/postgresql.jar.
The resulting driver will be built for the version of Java you are
running. If you build with a 1.4 or 1.5 JDK you will build a version that supports the
JDBC 3 specification and if you build
with a 1.6 or higher JDK you will build a version that
supports the JDBC 4 specification.