策略模式之前

/**
 * 策略模式之前
 * <p>
 * 例子：
 * 穿白色的衣服返回口红100号
 * 穿红色的衣服返回口红300号
 * .....
 */
public class NoStrategy {

    public static int getLipstick(String clothes) {

        if ("white".equals(clothes)) {
            return 1;
        } else if ("red".equals(clothes)) {
            return 2;
        } else if ("yellow".equals(clothes)) {
            return 3;
        }
        return 0;
    }
}

策略模式

/**
 * 策略接口
 */
public interface ClothesLipstick {
    int getLipstick();
}


/**
 * 白色衣服策略接口实现
 */
public class WhiteClothesLipstick implements ClothesLipstick {
    @Override
    public int getLipstick() {
        return 1;
    }
}

/**
 * 红色策略接口模式
 */
public class RedClothesLipstick implements ClothesLipstick {
    @Override
    public int getLipstick() {
        return 2;
    }
}

/**
 * 黄色衣服策略接口实现
 */
public class YellowClothesLipstick implements ClothesLipstick {
    @Override
    public int getLipstick() {
        return 3;
    }
}

使用方式

public class StrategyDemo {

    public static void main(String[] args) {
        noStrategy();
        System.out.println("====");
        strategy();

    }

    /**
     * 不用策略模式
     */
    private static void noStrategy() {
        List<String> clothes = Lists.newArrayList();
        clothes.add("red");
        clothes.add("white");
        clothes.add("yellow");
        clothes.stream().forEach(item -> System.out.println(item + ":" + NoStrategy.getLipstick(item)));

    }

    /**
     * 使用策略模式
     */
    private static void strategy() {

        Map<String, ClothesLipstick> map = Maps.newHashMap();

        map.put("red", new RedClothesLipstick());
        map.put("white", new WhiteClothesLipstick());
        map.put("yellow", new YellowClothesLipstick());

        map.forEach((k, v) -> System.out.println(k + ":" + v.getLipstick()));


    }

}

总结：对修改关闭，对扩展开放。代码的扩展性更好