How to implement odata producer for mysql or postgresql

I would like to learn how to provide Odata service from MySQL OR PostgreSQL using Java. I tried https://code.google.com/p/odata4j/ . After running the sample app from odata4j, I can't see any Odata service. I tried a couple of others. Unfortunately none of them successfully provide the odata service from the database.

I was able to start the odata console service without any real database http://www.odata.org/getting-started/basic-tutorial . This gives me a good idea of ​​how the odata service works in general.

I want to study or see some example that provides odata service from any database using Java. Please let me know. Thank you in advance!