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Can You Explain the Role Session Interface Plays in Hibernate?

Published in Database & ORM 2 mins read

The Session interface in Hibernate acts as the primary communication channel between your Java application and the database. It's the central component responsible for managing object persistence, interacting with the database, and executing queries.

Here's a breakdown of its key roles:

Managing Object Persistence

  • Saving Objects: The Session interface provides methods like save() and persist() to store new objects in the database.
  • Updating Objects: When changes are made to an object in your application, the Session interface facilitates updating the corresponding record in the database using methods like update() and merge().
  • Deleting Objects: The Session interface allows you to remove objects from the database using the delete() method.
  • Loading Objects: The Session interface provides the get() and load() methods to retrieve objects from the database based on their primary key.

Interacting with the Database

  • Executing Queries: The Session interface allows you to execute SQL queries using the createSQLQuery() method. You can also execute Hibernate Query Language (HQL) queries using createQuery().
  • Transaction Management: The Session interface provides methods for managing database transactions. You can start, commit, and rollback transactions to ensure data integrity.

Example

Session session = sessionFactory.openSession(); // Obtain a Session instance
Transaction tx = session.beginTransaction(); // Begin a transaction

// Save a new object
Customer customer = new Customer("John Doe");
session.save(customer); 

// Update an existing object
Customer existingCustomer = session.get(Customer.class, 1);
existingCustomer.setName("Jane Doe");
session.update(existingCustomer);

// Delete an object
session.delete(existingCustomer);

tx.commit(); // Commit the transaction
session.close(); // Close the Session

Practical Insights

  • The Session interface is designed to be used within a single transaction.
  • It's generally recommended to create a new Session for each database interaction to maintain isolation.
  • The Session interface is thread-unsafe and should not be shared across multiple threads.

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