Many JDBC JAR files (such as the Derby driver included with Java SE 7) automatically register the driver class. In that case, you can skip the manual registration step that we describe in this section. A JAR file can automatically register the driver class if it contains a file
META-INF/services/java.sql.Driver. You can simply unzip your driver’s JAR file to check.
This registration mechanism uses a little-known part of the JAR specification; see http://docs.oracle.com/javase/7/docs/technotes/guides/jar/jar.html#Service_Provider. Automatic registration is a requirement for a JDBC4-compliant driver.