1策略模式.docx

策略模式的定义 定义一组算法，将每个算法都封装起来，并且使它们之间可以互换。 策略模式使这些算法在客户端调用它们的时候能够互不影响地变化? 策略模式的组成 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 环境角色：持有一个策略类的引用，最终给客户端调用的。抽象策略角色public interface Strategypublic int calculate(int a, int b);具体策略角色/除public class DivideStrategy implements Strategypublic int calculate(int a, int b)return a / b;/减public class SubtractStrategy implements Strategypublic int calculate(int a, int b)return a - b;/加public class AddStrategy implements Strategypublic int calculate(int a, int b)return a + b;/乘public class MultiplyStrategy implements Strategypublic int calculate(int a, int b)return a * b;环境角色public class Environmentprivate Strategy strategy;public Environment(Strategy strategy)this.strategy = strategy;public Strategy getStrategy()return strategy;public void setStrategy(Strategy strategy)this.strategy = strategy;public int calculate(int a ,int b)return strategy.calculate(a , b);客户端调用public class Clientpublic static void main(String args)AddStrategy addStrategy = new AddStrategy();Environment environment = new Environment(addStrategy);System.out.println(environment.calculate(3, 4);SubtractStrategy subtractStrategy = new SubtractStrategy();environment.setStrategy(subtractStrategy);System.out.println(environment.calculate(3, 4);MultiplyStrategy multiplyStrategy = new MultiplyStrategy();environment.setStrategy(multiplyStrategy);System.out.println(environment.calculate(3, 4);DivideStrategy divideStrategy = new DivideStrategy();environmen