学习笔记之策略模式

策略（Strategy）模式：定义了算法族，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。属于设计模式中对象行为型模式。


下面看代码：

抽象类Duck.java

package org.kangsg219.abst;

import org.kangsg219.intf.FlyBehavior;
import org.kangsg219.intf.QuackBehavior;

public abstract class Duck {
	
	public FlyBehavior flybehavior;
	
	public QuackBehavior quackbehavior;
	
	public Duck(){
		
	}
	
	public abstract void display();
	
	public void performFly(){
		flybehavior.fly();
	}
	
	public void setFlybehavior(FlyBehavior flybehavior) {
		this.flybehavior = flybehavior;
	}

	public void setQuackbehavior(QuackBehavior quackbehavior) {
		this.quackbehavior = quackbehavior;
	}

	public void performQuack(){
		quackbehavior.quack();
	}
	
	public void swim(){
		System.out.println("All ducks float,even decoys!");
	}
}

duck具备两个行为：飞和叫；先分别定义接口再实现

package org.kangsg219.intf;

public interface FlyBehavior {
	public void fly();
}

package org.kangsg219.intf;

public interface QuackBehavior {

	public void quack();
}

package org.kangsg219.impl;

import org.kangsg219.intf.FlyBehavior;

public class FlyNoWay implements FlyBehavior {

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

	}

}

package org.kangsg219.impl;

import org.kangsg219.intf.FlyBehavior;

public class FlyWithRocket implements FlyBehavior {

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

}

package org.kangsg219.impl;

import org.kangsg219.intf.FlyBehavior;

public class FlyWithWings implements FlyBehavior {

	public void fly() {
		System.out.println("I'm flying with wings!");

	}

}

package org.kangsg219.impl;

import org.kangsg219.intf.QuackBehavior;

public class MuteQuack implements QuackBehavior {

	public void quack() {
		System.out.println("<silence>");

	}

}

package org.kangsg219.impl;

import org.kangsg219.intf.QuackBehavior;

public class Quack implements QuackBehavior {

	public void quack() {
		System.out.println("Quack......");

	}

}

package org.kangsg219.impl;

import org.kangsg219.intf.QuackBehavior;

public class Squeak implements QuackBehavior {

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

	}

}

看看效果

package org.kangsg219.test;

import org.kangsg219.abst.Duck;
import org.kangsg219.impl.FlyWithWings;
import org.kangsg219.impl.Quack;



public class MallardDuck extends Duck {

	public MallardDuck(){
		quackbehavior=new Quack();
		flybehavior=new FlyWithWings();
	}
	
	@Override
	public void display() {
		System.out.println("I'm a real mallard duck!");

	}

}

package org.kangsg219.test;

import org.kangsg219.abst.Duck;
import org.kangsg219.impl.FlyWithRocket;
import org.kangsg219.impl.Quack;

public class MiniDuckSimulator {

	
	public static void main(String[] args) {
		
		System.out.println("mallard duck********************");
		Duck mallard=new MallardDuck();
		mallard.performFly();
		mallard.performQuack();
		mallard.swim();
		mallard.display();
		
		System.out.println("modle duck********************");
		Duck modle=new ModleDuck();
		modle.setFlybehavior(new FlyWithRocket());
		modle.setQuackbehavior(new Quack());
		modle.performFly();
		modle.performQuack();
		modle.swim();
		modle.display();
		
	}

}

package org.kangsg219.test;

import org.kangsg219.abst.Duck;

public class ModleDuck extends Duck {

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

	}

}

评论

2 楼 bomb2121 2008-01-07  

老弟，做的不错哈。不过要能多加上一点你自己的想法就更好了。
策略模式：在spring中最是常用的。看看spring对各个层面中提供的集成多种框架的能力就知道了：）

1 楼 kangsg219 2007-10-19  

代码来自《Head First 设计模式》