Esto funciona...
import java.io.FileReader;
import java.sql.Connection;
import java.sql.DriverManager;
import org.postgresql.copy.CopyManager;
import org.postgresql.core.BaseConnection;
public class PgSqlJdbcCopyStreamsExample {
public static void main(String[] args) throws Exception {
if(args.length!=4) {
System.out.println("Please specify database URL, user, password and file on the command line.");
System.out.println("Like this: jdbc:postgresql://localhost:5432/test test password file");
} else {
System.err.println("Loading driver");
Class.forName("org.postgresql.Driver");
System.err.println("Connecting to " + args[0]);
Connection con = DriverManager.getConnection(args[0],args[1],args[2]);
System.err.println("Copying text data rows from stdin");
CopyManager copyManager = new CopyManager((BaseConnection) con);
FileReader fileReader = new FileReader(args[3]);
copyManager.copyIn("COPY t FROM STDIN", fileReader );
System.err.println("Done.");
}
}
}