Creational Patterns : Abstract Factory

Properties:

-          Similar to simple factory. However there are multiple factory classes which shares a common abstract factory class and each of them is responsible for creating a different family of XYZ classes. XYZ here means a factory product. XYZ1 and XYZ2 are different products.

-          Actual factory implementation is chosen like the way factory class itself choses its XYZ implementation. In this manner Abstract Factory Pattern can be regarded as Factory for Factory Classes.

-          Identified by an abstract factory (interface as well) class defining root of factory hieracrchy and multiple factory implementations.

Implementation:

-          An abstract factory class defines root for Factory hierarchy.

-          Each Factory implementation has its own way creating a XYZ class instance.

-          Suitable factory instance is selected and used to create XYZ instances.

Java Standard Library Implementations:

-          Java.sql.Connection

Example Usage:

// Connection interface is abstract factory class.

// Obtain factory instance : For Mysql database

// com.mysql.jdbc.ConnectionImpl instance is returned.

Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/3306"

              + "user=user&password=password");

// creator method createStatement(): returns concrete

// com.mysql.jdbc.StatementImpl instance

Statement statement = conn.createStatement();

// creator method prepareStatement(): returns

// concrete com.mysql.jdbc.PreparedStatement

PreparedStatement preparedStatement =

conn.prepareStatement("select * from person");