工厂模式

工厂模式：“工厂”生活中是生产东西的地方，在Java世界里工厂是生产对象实例的。
工厂的作用：使代码与实现类分离，这样方便我们替换实现。
工厂的动作：选择实现——根据条件提供对应的对象实例。

这几天学习了下《Thinking in Java》中“接口”这个章节。觉得该章中关于工厂的设计例子蛮有意思的，参照它写了如下一个例子：

public interface Cycle {
	public void run();
}

public class UniCycle implements Cycle {

	@Override
	public void run() {
		// TODO Auto-generated method stub
		System.out.println("Cycle Run");
	}

}

public class BiCycle implements Cycle {

	@Override
	public void run() {
		// TODO Auto-generated method stub
		System.out.println("BiCycle Run");
	}

}

public class TriCycle implements Cycle {

	@Override
	public void run() {
		// TODO Auto-generated method stub
		System.out.println("TriCycle Run");
	}

}

下面是工厂：

public interface CycleFactory {
	public Cycle getCycle();
}

public class UniCycleFactory implements CycleFactory {

	@Override
	public Cycle getCycle() {
		// TODO Auto-generated method stub
		return new UniCycle();
	}

}

public class BiCycleFactory implements CycleFactory {

	@Override
	public Cycle getCycle() {
		// TODO Auto-generated method stub
		return new BiCycle();
	}

}

public class TriCycleFactory implements CycleFactory {

	@Override
	public Cycle getCycle() {
		// TODO Auto-generated method stub
		return new TriCycle();
	}

}

测试代码：

public class FactoryTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		run(new UniCycleFactory().getCycle());
		run(new BiCycleFactory().getCycle());
		run(new TriCycleFactory().getCycle());
		
		run(new UniCycleFactory());
		run(new BiCycleFactory());
		run(new TriCycleFactory());
	}
	
	public static void run(Cycle cycle){
		cycle.run();
	}
	
	public static void run(CycleFactory cycleFactory){
		Cycle cycle = cycleFactory.getCycle();
		cycle.run();
	}

}

运行结果:
Cycle Run
BiCycle Run
TriCycle Run
Cycle Run
BiCycle Run
TriCycle Run

感觉这样设计工厂有点做作，可能为了强调“接口”吧