策略模式

策略模式是对算法的包装, 是把使用算法的责任和算法本身分割开来, 委派给不同的对象管理.

策略模式通常把一个系列的算法包装到一系列的策略类里面, 作为一个抽象策略类的子类.

一句话来形容: 准备一组算法, 并将每一个算法封装起来, 使得他们可以互换.

策略模式的结构:

策略模式 涉及到三个角色:

环境角色: 持有一个Strategy 类(策略类)的引用

抽象策略角色: 策略类, 通常由一个接口或者抽象类实现

具体策略角色: 包装了相关的算法和行为. package com.deng.DesignPattern.Strategy; public abstract class Operation { public abstract void oper(float a, float b); }

package com.deng.DesignPattern.Strategy; public class Add extends Operation { public void oper(float a, float b) { float result = a+ b; System.out.println("相加的结果为: "+result); } }

package com.deng.DesignPattern.Strategy; public class Jian extends Operation { public void oper(float a, float b) { float result = a- b; System.out.println("相减的结果为: "+result); } }

package com.deng.DesignPattern.Strategy; public class Cheng extends Operation { public void oper(float a, float b) { float result = a* b; System.out.println("相乘的结果为: "+result); } }

package com.deng.DesignPattern.Strategy; public class Chu extends Operation { public void oper(float a, float b) { float result = a/ b; System.out.println("相除的结果为: "+result); } }

package com.deng.DesignPattern.Strategy; public class Calc { private Operation o ; public final static Operation add = new Add(); public final static Operation jian = new Jian(); public final static Operation cheng = new Cheng(); public final static Operation chu = new Chu(); public void oper(float a , float b ){ o.oper(a, b); } }

package com.deng.DesignPattern.Strategy; public class Test { public static void main(String[] args) { float a = 100; float b = 25; Calc c = new Calc(); c.add.oper(a, b); } }