JDBC API specification and implementation

Question

I was going through JDBC API's (mainly java.sql package) after writing some simple JDBC programs.

For example, in java.sql, the below is the declaration:

public interface Connection extends Wrapper, AutoCloseable

So, as per my understanding, these specifications have to be implemented by database vendors, in the form of JDBC drivers.

In my sample program i used H2 db, so i downloaded the JDBC driver.

Now, this jar should have implementation of java.sql.Connection, and this is what i saw in the .jar (jdbc driver) for this (under package --> org.h2.jdbc):

public class org.h2.jdbc.JdbcConnection extends org.h2.message.TraceObject implements java.sql.Connection {

The jdbc driver jar does implement java.sql.Connection, as expected; however where does it get java.sql.Connection from? (it simply implements java.sql.Connection), where is the definition of java.sql.Connection coming from?

Any pointers to clear this doubt would be helpful.

As I also commented on the answer: you are using reverse engineered source of H2 instead of the actual source, which is usually easier to understand. — Mark Rotteveel
– Mark Rotteveel, Commented Jun 3, 2015 at 6:37

JB Nizet · Accepted Answer · 2015-06-02 17:57:39Z

4

It's in the JDK, since you were able to look at its documentation in the JDK javadoc.

answered Jun 2, 2015 at 17:57

JB Nizet

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5 Comments

CuriousMind Over a year ago

Thanks for your reply; so it means when they compile, they get definition from the JDK itself. If that is the case, i believe in the source code of the implementer, they would have statement like this: import java.sql.Connection.

JB Nizet Over a year ago

Yes, of course. Unless they're masochist and prefer typing java.sql.Connection every time.

CuriousMind Over a year ago

Thanks, I got it, downloaded mysql Connector/J source code to get a feel how they implement. Thanks again!

Mark Rotteveel Over a year ago

@vipinkoul Sometimes people don't use imports and use the fully qualified name of the class to avoid name-conflicts (eg MySQL has called their implementation classes the same as the interfaces in java.sql). Although in your specific case I guess you didn't actually download the sources, and have your IDE reverse engineer the Java code as the actual source isn't the same and does use imports: code.google.com/p/h2database/source/browse/trunk/h2/src/main/…

CuriousMind Over a year ago

@MarkRotteveel: Exactly i used eclipse IDE to get the source (albeit small source it shows). I otherwise downloaded Connector/J to understand it. Thanks a lot for sharing your expert advise. Best Regards

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