Submitted by heartin on Sat, 04/16/2016 - 13:35
A composite key is a primary key composed of multiple columns.
When you are creating a composite key, your persistent class must override the equals() and hashCode() method. This is required for for Hibernate caching to work correctly. It must also implement the Serializable interface.
Best way to do this is to create a class with all your composite key fields, mark it as @Embeddable and then annotate a field of that class type with @Id in your entity class.
Submitted by heartin on Fri, 04/15/2016 - 15:27
An entity is a type on its own and has an existence of its own (e.g. Course, User etc.).
A value type is a type which doesn't have existence of its own, but belongs to an entity (e.g. Address of an User). Value types are always completely owned by their containing entity.
Defining entities and value types in Hibernate
Submitted by heartin on Wed, 04/13/2016 - 21:16
You have different logging options in Hibernate and let us see some of those options quickly. Hibernate supports simple property based log enabling to supporting standard logging frameworks and even programmatically accessing log statistics.
Submitted by heartin on Wed, 04/13/2016 - 20:54
We use various materials like books, internet resources etc. for our learning, for teaching and even for preparing notes. We will list those materials here for your reference. We might include only the very basic information required for our learning and training purposes here. You may refer to these additional materials for further reading and learning.
Submitted by heartin on Wed, 04/13/2016 - 09:00
In JPA, the EntityManager controls the lifecycle of the entities.
Different ORM vendors provide its own entity manager, which is usually a wrapper around the core API and thus supports the JPA programming interfaces, life cycles and query language.
You obtain the EntityManager from an entity manager factory. EntityManagerFactory has the same role as SessionFactory in Hibernate.
Submitted by heartin on Tue, 04/12/2016 - 21:18
A software framework is a reusable software platform that makes the life of developers easy by providing something commonly needed out of the box; developers can then use it or extend it.
For instance, Struts basically provides a MVC framework by providing a controller out of the box and an xml mechanism to configure MVC using xml files without hardcoding them in the code.
Submitted by heartin on Tue, 04/12/2016 - 20:17
These are some of the commonly asked questions to check if you know the differences between important concepts or APIs in Hibernate. This may contain beginner to advanced level questions.
Differentiate between entities and value types in Hibernate.
What is the difference between save() and persist() methods in Hibernate?
What is the difference between get and load methods in hibernate?
Submitted by heartin on Tue, 04/12/2016 - 19:30
Before working with hibernate in your code, you will need to configure Hibernate with information regarding your database such as host, port, credentials etc. You also need to create mappings that tell hibernate how to map the state of a Java entity to the columns of its corresponding table.
We can configure various hibernate features either through annotations or through xml files (hbm files). Preferred approach currently is annotations.
You can configure Hibernate mainly in three ways:
Submitted by heartin on Mon, 04/11/2016 - 22:52
This is a list of basic questions from Hibernate which you can use to check your understanding or even prepare for interviews. You may use the parent chapter, other chapters or hibernate or the forum to discuss more on these questions.
What is a framework?
What do you mean by CRUD?
What is Hibernate? What are the advantages of using Hibernate?
What is Java Persistence API (JPA)?
Submitted by admin on Fri, 04/08/2016 - 20:46
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