Application of design patterns in Hibernate framework

The Hibernate framework makes extensive use of design patterns to implement its functionality, including: Factory pattern: Create a SessionFactory object to create a Session object. Proxy mode: Lazy loading of entities, loading actual entities only when needed. Unit State Pattern: Tracks the lifecycle state of entities in the database. Strategy pattern: dynamic selection of algorithms or behaviors, such as database interaction strategies.

Design Patterns in Hibernate Framework

Hibernate framework extensively adopts various design patterns to implement its functionality, which simplify Development and maintenance of persistence logic. The following are the most commonly used design patterns in Hibernate:

Factory Pattern:

Factory pattern creates an object without specifying the concrete class of the object. In Hibernate, the SessionFactory class is used to create Session objects, which are the entry points for persistence operations. <pre class='brush:java;toolbar:false;'>// 创建一个 SessionFactory SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory(); // 创建一个 Session Session session = sessionFactory.getCurrentSession();</pre>

Proxy pattern:

The proxy pattern provides a proxy for another object with controlled access to that object. Hibernate uses proxy pattern to lazy load entities. The entity's proxy object only loads the actual entity when needed.

Unit State Mode:

Unit State Mode tracks the life cycle state of objects in the database. Hibernate uses

Session

objects to manage the state of entities, including Transient, Persistent, Detached and Removed.

Strategy Mode:

Strategy mode allows dynamic selection of algorithms or behaviors. Hibernate uses the Strategy pattern to determine how entities interact with the database. For example, different databases require different generator strategies to generate unique identifiers.

Practical case: Using the DAO design pattern in Hibernate

The Data Access Object (DAO) design pattern isolates the application's business logic from the data persistence layer . In Hibernate, you can create a DAO class by implementing the DAO interface.

public interface PersonDAO {
    Person getPerson(int id);
    void savePerson(Person person);
    void deletePerson(int id);
}

public class PersonDAOImpl implements PersonDAO {

    @Override
    public Person getPerson(int id) {
        return session.get(Person.class, id);
    }

    @Override
    public void savePerson(Person person) {
        session.save(person);
    }

    @Override
    public void deletePerson(int id) {
        Person person = session.get(Person.class, id);
        session.delete(person);
    }
}

Using the DAO pattern simplifies interaction with Hibernate and decouples it from business logic.

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