策略模式

1.概述

策略模式是封装一组算法，在程序运行的过程中根据不同情况执行相应的算法。

2.UML结构图

image.png

3.代码实现：

Strategy:策略接口

/**
 * Created by zhouwen on 2019/7/13 17:16
 */
public interface Strategy {
    void doing();
}

ConcreteStrategyA:具体策略角色

/**
 * Created by zhouwen on 2019/7/13 17:16
 */
public class ConcreteStrategyA implements Strategy {
    @Override
    public void doing() {
        Logger.getLogger("ConcreteStrategyA").info("A doing");
    }
}

ConcreteStrategyB：具体策略角色

/**
 * Created by zhouwen on 2019/7/13 17:17
 */
public class ConcreteStrategyB implements Strategy{
    @Override
    public void doing() {
        Logger.getLogger("ConcreteStrategyB").info("B doing");
    }
}

StrategyContext：封装角色，屏蔽上层对具体策略直接访问

/**
 * Created by zhouwen on 2019/7/13 17:17
 */
public class StrategyContext {
    private Strategy mStrategy;

    public StrategyContext(Strategy mStrategy) {
        this.mStrategy = mStrategy;
    }

    public void doing(){
        mStrategy.doing();
    }
}

StrategyClient：场景类

/**
 * Created by zhouwen on 2019/7/13 17:31
 */
public class StrategyClient {
    public void test(){
        Strategy strategya = new ConcreteStrategyA();
        Strategy strategyb = new ConcreteStrategyB();

        StrategyContext strategyContext = new StrategyContext(strategya);
        strategyContext.doing();

        strategyContext = new StrategyContext(strategyb);
        strategyContext.doing();
    }
}