Pattern – Abstract Factory

What: Provides an interface for creating families of related or dependent objects without specifying their concrete classes.

Best use case: When you need to create families of objects that work together, like UI elements for different platforms.

Diagram

How it works:

• Abstract Factory Interface (DAOFactory):
  • Defines a common interface for creating different types of DAOs (ProductDAO and UserDAO).
• Concrete Factory Classes (MySQLDAOFactory, PostgreSQLDAOFactory):
  • Implement the DAOFactory interface.
  • Create concrete DAO objects (MySQLProductDAO, MySQLUserDAO, PostgreSQLProductDAO, PostgreSQLUserDAO) specific to the database system.
• Abstract Product Interfaces (ProductDAO, UserDAO):
  • Define the common interface for database operations on products and users.
• Concrete Product Classes (MySQLProductDAO, MySQLUserDAO, PostgreSQLProductDAO, PostgreSQLUserDAO):
  • Implement the corresponding abstract product interface.
  • Provide database-specific implementations for the operations.

By using the Abstract Factory pattern, you can easily switch between different database systems without modifying the core application logic. You simply need to change the concrete factory implementation to create DAOs for the desired database. This promotes loose coupling, flexibility, and testability in your application.