设计模式：策略模式的实现

最新推荐文章于 2025-02-28 00:15:00 发布

Arvon_阿文

最新推荐文章于 2025-02-28 00:15:00 发布

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分类专栏：设计模式文章标签：设计模式策略模式 strategy pattern

本文链接：https://blog.youkuaiyun.com/wen942467928/article/details/47953385

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本文通过鸭子的行为模拟，详细介绍了策略模式的设计理念及其应用场景。策略模式允许在运行时选择不同的算法，使得算法的选择与使用它的对象解耦。

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1. 策略模式:定义了算法族，分别封装起来，让它们之间可以替换，此模式让算法的变化独立于使用该算法的用户。（利用组合）

类图如下:

源代码如下：

package Strategy;
/**
 * 鸭子超类
 * @author Arvon
 *
 */
public abstract class Duck {
	public Duck() {
		super();
		// TODO Auto-generated constructor stub
	}
	 FlyBehavior mFlyBehavior; //has A 组合行为
	 QuackBehavior mQuackBehavior; //has A 组合行为
	public void swim(){
		System.out.println("All ducks float, even decoys!");
	}
	public abstract void display();
	public   void performFly(){
		mFlyBehavior.fly(); //委托给行为类处理
	}
	public   void performQuack(){
		mQuackBehavior.quack(); //委托给行为类处理
	}
	public void setmFlyBehavior(FlyBehavior mFlyBehavior) {
		this.mFlyBehavior = mFlyBehavior;
	}
	public void setmQuackBehavior(QuackBehavior mQuackBehavior) {
		this.mQuackBehavior = mQuackBehavior;
	}
		
	

}

package Strategy;
/**
 * 飞行类鸭子的接口
 * @author Administrator
 *
 */
public interface FlyBehavior {
	public void fly();
}

package Strategy;
/**
 * 叫行为鸭子接口
 * @author Administrator
 *
 */
public interface QuackBehavior {
	public void quack();
}

package Strategy;

public class FlyNoWays implements FlyBehavior {

	@Override
	public void fly() {
		System.out.println("I can't fly");
	}

}

package Strategy;

public class FlyRocketPowered implements FlyBehavior {

	@Override
	public void fly() {
		// TODO Auto-generated method stub
		System.out.println("I'm flying with a rocket");
	}

}

package Strategy;

public class FlyWithWings implements FlyBehavior {

	@Override
	public void fly() {
		System.out.println("I'm flying!!");
	}

}

package Strategy;

public class Quack implements QuackBehavior {

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

}

package Strategy;

public class MuteQuack implements QuackBehavior {

	@Override
	public void quack() {
		// TODO Auto-generated method stub
		System.out.println("<< Silence >>");
	}

}

package Strategy;

public class Squeak implements QuackBehavior {

	@Override
	public void quack() {
		System.out.println("Squeak");

	}

}

package Strategy;

public class MallardDuck extends Duck {
	
	
	/**
	 * 申明我是一只用翅膀飞并会嘎嘎叫的鸭子
	 */
	public MallardDuck() {
		super();
		mFlyBehavior = new FlyWithWings();
		mQuackBehavior = new Quack();
	}

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

}

package Strategy;

public class DecoyDuck extends Duck {
	/**
	 * 申明我是一只不会叫也不会飞的鸭子
	 */
	public DecoyDuck() {
		super();
		// TODO Auto-generated constructor stub
		mFlyBehavior = new FlyNoWays();
		mQuackBehavior = new MuteQuack();
	}

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

	}

}

package Strategy;

public class ModelDuck extends Duck {

	
	public ModelDuck() {
		super();
		// TODO Auto-generated constructor stub
		mFlyBehavior = new FlyNoWays();
		mQuackBehavior = new Quack();
	}

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

}

package Strategy;
/**
 * 测试类
 * @author Administrator
 *
 */
public class MiniDuckSimulator {

	public static void main(String[] args) {
		Duck mallard = new MallardDuck();
		mallard.performFly();
		mallard.performQuack();
		mallard.display();
		
		Duck decoy = new DecoyDuck();
		decoy.performFly();
		decoy.performQuack();
		decoy.display();
		
		Duck model = new ModelDuck();
		model.performFly();;
		model.performQuack();
		model.display();
		//动态地改变鸭子的行为
		model.setmFlyBehavior(new FlyRocketPowered());
		model.performFly();;
		model.performQuack();
		model.display();
	}

}

程序的输出：

I'm flying!!
Quack
I'm a real Mallard duck
I can't fly
<< Silence >>
I'm a duck Decoy
I can't fly
Quack
I'm a model duck
I'm flying with a rocket
Quack
I'm a model duck