1. Introduction Hibernate

 Introduction Hibernate 


- Hibernate is a java framework that simplifies the developement of java application to intract with the Database.

 - It is invented by Gavin King in 2001.

- Hibernate is the ORM framework/tool .

- Hibernate Implement specifiaction of JPA ( Java Persistence API ) for the data persistence.

- Hibernate is non-inversive framework , means it wont forces to programmer to extend / implement any class/interface.

- We can build any type of application using hibernate.(like standalone, servlets , desktop etc)

- It is a java framework which is used to develop persistence logic. Persistence logic means to store and process the data for long use.


Advantages of Hibernates 

- Hibernate takes care of mapping Java classes to database tables using XML files and without writing any line of code.

- If there is change in the database or in any table, then you need to change the XML file properties only.

- Minimizes database access with smart fetching strategies.

- Fast Performace :  The performance of hibernate framework is fast because cache is internally used in hibernate framework.

- Database Independent Query : HQL (Hibernate Query Language) is the object-oriented version of SQL.

- Automatic Table Creation : Hibernate framework provides the facility to create the tables of the database automatically.



What is Persistence ?

- Persistance means process storing and managing tha data for long time.


Persistent classes

- Java classes whose objects or instances will be stored in database tables are called persistent classes in Hibernate. 

- Hibernate works best if these classes follow some simple rules, also known as the Plain Old Java Object (POJO) programming model.

- Peristence store : place where the data will be store.

- Peristent Data : the data of persistence is called persistence data Ex : file info , DB table & record 

-Persistence operation : insert , update , delete and select operations performed on persistent data. CRUD operation.

- Persitence Logic - The logic that is written to perform crud operation.


JPA : Java Persistence API 

- JPA stand for Java Persistence API. 

- The JPA specifcation was developed by java as a stadard way to map object to relational tables. 

- It is used to save data between java object and relational database. JPA acts as a bridge between object-orinted domain models and relational database system.

- JPA just provides the specification, it does not provide the implementation.

- So we cannot use JPA by itself , u will need to use a JPA provider that implements the JPA framwork.

- Eclipselink, TopLink ,iBatis and Hibernate are some frameworks that implement the JPA specificatoin.

- The advantage of using a framwork that implements the JPA specification is that you can easily switch the framekwork.




Comments

Post a Comment

Popular posts from this blog

5. JPA Relational Mapping & Fetch Types & Cascadding

 RelationShip  -OneToOne -OneToMany -ManyToOne -ManytoMany Fetch Types 1. FetchType.LAZY  2. FetchType.EAGER In Hibernate, the "fetch type" determines how associated data should be loaded from the database.  It's like specifying whether you want to load related data eagerly (at the same time as the main entity) or lazily (only when needed). There are two main fetch types in Hibernate: 1. Eager Fetch Type    - When you fetch data eagerly, Hibernate loads the main entity along with its associated data immediately.    - It's like ordering a combo meal at a restaurant – you get the burger and fries together, even if you're not going to eat the fries right away.    - Eager loading can lead to loading more data than necessary, which may impact performance if not used carefully. 2. Lazy Fetch Type:    - When you fetch data lazily, Hibernate loads the main entity first and only loads associated data when explicitly requested. ...
Read more

4. Data Fetching Methods & @Embeddable annotation in Hibernate

  Data Fetching from Database In Hibernate, the `get` and `load` methods are used to retrieve an object from the database based on its primary key. Both methods are part of the `Session` interface in Hibernate. 1. get() method: - The get() method is a part of the Hibernate Session interface. - It retrieves an entity(persistence) object from the database by its primary key (ID). -  It takes the class of the object to be retrieved and the primary key of the object as arguments. - get() method only hits the database if the object is not present in the session cache.   - get() method returns null if there is no object present in the database.    Example:       Session session = sessionFactory.openSession();    Transaction transaction = session.beginTransaction();    // Get an object by its primary key    Employee employee = (Employee) session.get(Employee.class, 1L);    transaction.commit();    se...
Read more

6. Hibernate Query Language (HQL) & Caching in Hibernate

  Hibernate Query Language (HQL) Hibernate Query Language (HQL) is a powerful and flexible way to interact with a relational database using Hibernate, which is a popular Object-Relational Mapping (ORM) framework in Java.  1. HQL - Hibernate Query Language:    - HQL is like SQL, but it's designed to work with your Java objects, not directly with the database tables. It allows you to write queries using the names of your Java classes and properties, rather than database tables and columns. 2. Database Interaction - In traditional database operations, you use SQL (Structured Query Language) to interact with the database. SQL is a language that is specific to the database you are using (e.g., MySQL, PostgreSQL, Oracle). 3. Object-Relational Mapping (ORM): Hibernate helps you work with databases in a more object-oriented way. Instead of thinking in terms of database tables and SQL queries, you can work with Java objects that map to your database tables. Caching in Hiberna...
Read more