Java Rant Episode 3 - Hibernate – March 21st 2008
Show Notes…
Welcome back to the Java Rant podcast
Hibernate
Who is it?
- JBoss (Redhat)
- does not require you to use JBoss application server
- professional open source project
- JBoss uses Hibernate for their implementation of their JavaEE technology stack
What is it?
- ORM - Object Relational persistence and query service
- Lets you program using Object Oriented techniques while interacting with the database.
- associations
- inheritance
- polymorphism
- composition
How does it work?
- Setup
- Configure hibernate to map your POJOs to the db tables and columns
- Configure hibernate what the relationships of your POJOs are
- Set up the connections
- Hibernate has a tool to reverse engineer an existing database schema
- Using hibernate
- everything revolves around POJOs and Sessions
- How to insert
- How to update
- Querying
- SQL
- Query API
- HQL
Why use it?
- Don’t kill a fly with a bazooka!!!!!
- Drastically cuts down on the development time
- If you have more than just one person working on the project
Gotchas!
- Don’t forget that you are working with a database
- Use the “recommended patterns of usage”
http://www.hibernate.org
Three challenges
Challenges
- Beginners
- Create a bean named Person that has two members: first name and last name
- Don’t forget to do some research to find out what it takes to make a “Java Bean”
- Create 3 or 4 Person objects, populate their members and add each one to a list.
- Make sure that the list uses generics so that only a Person object can be added to it
- Then loop through the list using the extended for loop syntax that was new in Java 5
- While in the loop, print out the Person’s first and last name
Intermediate
- Take the beginner’s challenge and extend it to Hibernate
- Map the Person bean to a table in your database
- Once you have inserted a few rows into your Person table, write a query that pulls all people out of the database, loops over the results, and print out their names.
- Advanced
- The advanced challenge will show a higher level function of Hibernate.
- You will make the Person object from the Intermediate challenge, but then you will also create two subclasses, Parent and Child
- These classes will have the name members from the Person object but they will also have members of their own
- The Parent class will have a salary member and the Child class will have a schoolName member.
- Both of these new fields will be added to your database schema but will only be selected when you query for the associated objects.
- To show that your setup is working, create two queries, one for pulling all Parents and one for pulling all Children. Print out the corresponding members of the objects.
Thanks
- Jordan Richley for the JavaRant artwork
- Feedburner.com for the feed redirects
- Theme Music
- Opening -”Motherboard” composed by Andy Potterton, published by Perfect Solution Music
- Closing - “Quick Escape” by Hot Like Cajun from www.hotlikecajun.com
- Contact
- http://www.javarant.com
- http://groups.google.com/group/javarant
- Call with questions or feedback - 206-350-8705
- or email comments@javarant.com
