Strategy

有一个鸟类(Bird),它有一系列的方法,显示(display)方法,飞行(fly)方法,睡觉(sleep)方法,但是不同的鸟的外表(display方法实现)不一样,有的鸟不会飞,有的鸟站着睡……
下面用策略模式实现
策略模式:定义算法族,分别封装起来,让它们之间可以互相替换,此模式让算法的变化独立于使用算法的客户
FlyBehavior接口代码如下:

package com.flyingh.behavior;

public interface FlyBehavior {
	void fly();
}

SleepBehavior接口代码如下:

package com.flyingh.behavior;

public interface SleepBehavior {
	void sleep();
}

下面是对FlyBehavior行为接口的实现:
FlyNoWay代码如下:

package com.flyingh.fly.impl;

import com.flyingh.behavior.FlyBehavior;
//不会飞
public class FlyNoWay implements FlyBehavior {

	@Override
	public void fly() {
		System.out.println("fly no way");
	}

}

FlyWithWings代码如下:

package com.flyingh.fly.impl;

import com.flyingh.behavior.FlyBehavior;

public class FlyWithWings implements FlyBehavior {

	@Override
	public void fly() {
		System.out.println("fly with wings");
	}

}

下面是对SleepBehavior行为的不同实现:
HomeSleep代码如下:

package com.flyingh.sleep.impl;

import com.flyingh.behavior.SleepBehavior;

public class HomeSleep implements SleepBehavior {

	@Override
	public void sleep() {
		System.out.println("home sleep");//在鸟窝里睡
	}

}

StandSleep代码如下:

package com.flyingh.sleep.impl;

import com.flyingh.behavior.SleepBehavior;

public class StandSleep implements SleepBehavior {

	@Override
	public void sleep() {
		System.out.println("stand sleep");//站着睡
	}

}

下面是Bird类的代码,如下:

package com.flyingh.bean;

import com.flyingh.behavior.FlyBehavior;
import com.flyingh.behavior.SleepBehavior;

public abstract class Bird {
	//委托
	private FlyBehavior flyBehavior;
	private SleepBehavior sleepBehavior;

	public Bird() {
		super();
	}

	public Bird(FlyBehavior flyBehavior, SleepBehavior sleepBehavior) {
		super();
		this.flyBehavior = flyBehavior;
		this.sleepBehavior = sleepBehavior;
	}

	public void say() {
		System.out.println("bird say");
	}

	public abstract void display();

	public void performFly() {
		flyBehavior.fly();
	}

	public void performSleep() {
		sleepBehavior.sleep();
	}

	public FlyBehavior getFlyBehavior() {
		return flyBehavior;
	}

	public void setFlyBehavior(FlyBehavior flyBehavior) {
		this.flyBehavior = flyBehavior;
	}

	public SleepBehavior getSleepBehavior() {
		return sleepBehavior;
	}

	public void setSleepBehavior(SleepBehavior sleepBehavior) {
		this.sleepBehavior = sleepBehavior;
	}
}

下面是Swallow类的代码,如下:

package com.flyingh.bean;

import com.flyingh.fly.impl.FlyWithWings;
import com.flyingh.sleep.impl.HomeSleep;

public class Swallow extends Bird {
	public Swallow() {
		setFlyBehavior(new FlyWithWings());
		setSleepBehavior(new HomeSleep());
	}

	@Override
	public void display() {
		System.out.println("I'm a swallow");
	}

}

下面是DanDingHe类的代码,如下:

package com.flyingh.bean;

import com.flyingh.fly.impl.FlyNoWay;
import com.flyingh.sleep.impl.StandSleep;

public class DanDingHe extends Bird {

	public DanDingHe() {
		setFlyBehavior(new FlyNoWay());
		setSleepBehavior(new StandSleep());
	}

	@Override
	public void display() {
		System.out.println("I'm a dandinghe");
	}

}

下面是Test类的代码,如下:

package com.flyingh.test;

import com.flyingh.bean.Bird;
import com.flyingh.bean.Swallow;
import com.flyingh.fly.impl.FlyNoWay;
import com.flyingh.sleep.impl.StandSleep;

public class Test {
	public static void main(String[] args) {
		Bird bird = new Swallow();
		bird.performFly();
		bird.performSleep();

		bird.setFlyBehavior(new FlyNoWay());
		bird.setSleepBehavior(new StandSleep());
		bird.performFly();
		bird.performSleep();
	}
}

程序运行结果如下:

fly with wings
home sleep
fly no way
stand sleep