工厂方法模式：定义一个用于创建对象的接口，但是让子类来决定到底创建哪一个实例。工厂方法模式让一个类的实例化延迟到其子类。工厂方法模式同样属于类的创建型模式又被称为多态工厂模式

实例：

//Abstract product roles
interface Events{
 public void decEvents();
}

//Click on the event,The specific role
class ClickEvents implements Events{
 public void decEvents(){
    LogHelper.w("This event is a click event"); 
 }
}


//Search on the event,The specific role
interface SearchEvents{
 public void decEvents(){
    LogHelper.w("This event is a search event"); 
 }
}

//Login on the event,The specific role
interface LoginEvents{
 public void decEvents(){
    LogHelper.w("This event is a login event"); 
 }
}

//Abstract factory role
public interface EventsFactory{
  public Events createEvents();
}

//Click on the factory interface
public interface ClickEventsFactory implements EventsFactory {

  @Override
  public Events createEvents(){
     Events events = new ClickEvents();
     return events;
  }
}

//Search on the factory interface
public interface SearchEventsFactory implements EventsFactory {

  @Override
  public Events createEvents(){
     Events events = new SearchEvents();
     return events;
  }
}

//Login on the factory interface
public interface LoginEventsFactory implements EventsFactory {

  @Override
  public Events createEvents(){
     Events events = new LoginEvents();
     return events;
  }
}

在MainActivity点击事件中实例化，并使用：

  EventsFactroy factory;
  Events events;

  //Click product
  factory = new ClickEventsFactory();
  events = factory.createEvents();
  events.decEvents();

  //search product
  factory = new SearchEventsFactory();
  events = factory.createEvents();
  events.decEvents();
  
  //Login product
  factory = new LoginEventsFactory();
  events = factory.createEvents();
  events.decEvents();

显示结果:
This event is a click event
This event is a search event
This event is a login event