one note of Head first design patterns(factory pattern)

I read the chapter 4 of head first design pattern just now.I just sum  up my thought about the factory pattern.

      The factory pattern contains three pattern in general.here are they.the first is simple factory,the second

is factory method pattern ,and the last is abstract factory pattern.the three factory pattern all encapsulate the

creation of the object to low the coupling .

      The factory method pattern define an interface for creating the objects ,but lets the subclass decide  which

object to create. so it lets a class  defer instantiation to the subclass. and The abstract factory pattern provide

an interface for creating families of the related or dependent objects without specifying the concrete class .

what'more ,the abstract factory pattern use the factory pattern to create one concrete object of the family.  in

addition,the abstract factory pattern show us a oo design principle -dependency inversion principle.this principle

require us to design my system like this.we should let both high level component and the low level component

depend the abstraction,not to let the high level component depend the low level component.