Spring优雅的实现策略模式

作者: 传达室马大爷 | 来源:发表于2018-09-26 11:01 被阅读103次

源码

https://github.com/shawntime/shawn-design-pattern/

定义

定义了一些平行的算法组，分别封装起来，算法之间可以相互替换，此模式使算法的变化独立于调用者之外

算法结构

抽象策略角色（Strategy）：这是一个抽象类或者接口，将算法的行为进行封装，所有的策略类都要实现该接口
具体策略角色（ConcreteStrategy）：封装了具体的算法和行为
环境角色（Context）：持有一个抽象策略的引用，并提供统一调用的入口

结构代码

package com.shawntime.designpattern.strategy.demo;

/**
 * 抽象策略类
 */
public interface Strategy {

    // 策略方法
    void strategyInterface();
}

package com.shawntime.designpattern.strategy.demo;

/**
 * Created by shma on 2018/9/26.
 */
public class ConcreteStrategyA implements Strategy {

    public void strategyInterface() {
        // A相关业务
    }
}

package com.shawntime.designpattern.strategy.demo;

/**
 * Created by shma on 2018/9/26.
 */
public class ConcreteStrategyB implements Strategy {

    public void strategyInterface() {
        // B相关业务
    }
}

package com.shawntime.designpattern.strategy.demo;

/**
 * 环境角色类
 */
public class Context {

    private Strategy strategy;

    public Context(Strategy strategy) {
        this.strategy = strategy;
    }

    // 对外暴露的策略方法
    public void contextInterface() {
        strategy.strategyInterface();
    }

    public Strategy getStrategy() {
        return strategy;
    }

    public void setStrategy(Strategy strategy) {
        this.strategy = strategy;
    }
}

项目实例

背景

在项目中，根据专题id去获得该专题下活动的礼品信息，由于每个专题活动礼品的方式不同，相互之间没有关联，属于平级的行为，因而采用策略模式。

方案1：通过spring配置注入策略

public interface IGiftInfoStrategyService {

    GiftInfo getGiftInfo(int activityId);
}

/**
 * 夏季购车节
 */
@Service
public class SummerBuyDayGiftInfoStrategyService implements IGiftInfoStrategyService {

    @Resource
    private GiftInfoMapper giftInfoMapper;
    
    public GiftInfo getGiftInfo(int activityId) {
        // 从数据库中查询
        GiftInfo giftInfo = new GiftInfo();
        giftInfo.setGiftId(1);
        giftInfo.setGiftName("铁锅三件套");
        giftInfoMapper.getGiftInfoByActivityId(activityId)
        return giftInfo;
    }
}

/**
 * 双11活动
 */
@Service
public class DoubleElevenGiftInfoStrategyService implements IGiftInfoStrategyService {

    @Override
    public GiftInfo getGiftInfo(int activityId) {
        // 双11调用统一平台接口获取礼品信息
        GiftInfo giftInfo = new GiftInfo();
        giftInfo.setGiftId(902);
        giftInfo.setGiftName("空气净化器");
        return giftInfo;
    }
}

/**
 * 礼品信息环境角色类
 */
@Component
public class GiftInfoContext {

    // 注入的策略
    @Autowired
    private Map<Integer, IGiftInfoStrategyService> giftInfoStrategyServiceMap;

    // 对外暴露的统一获取礼品信息的返回
    public GiftInfo getGiftInfo(int subjectId, int activityId) {
        IGiftInfoStrategyService giftInfoStrategyService = giftInfoStrategyServiceMap.get(subjectId);
        Assert.assertNotNull(giftInfoStrategyService);
        return giftInfoStrategyService.getGiftInfo(activityId);
    }
}

/**
 * 礼品信息配置类
 */
@Configuration
public class GiftInfoConfig {

    @Resource
    private IGiftInfoStrategyService doubleElevenGiftInfoStrategyService;

    @Resource
    private IGiftInfoStrategyService summerBuyDayGiftInfoStrategyService;

    /**
     * 注入bean
     */
    @Bean
    public Map<Integer, IGiftInfoStrategyService> giftInfoStrategyServiceMap() {
        Map<Integer, IGiftInfoStrategyService> dataMap = new HashMap<>();
        dataMap.put(1, summerBuyDayGiftInfoStrategyService);
        dataMap.put(2, doubleElevenGiftInfoStrategyService);
        return dataMap;
    }
}

/**
 * 礼品信息调用
 */
public class GiftInfoTest {

    @Resource
    private GiftInfoContext giftInfoContext;

    public GiftInfo getGiftInfo(int subjectId, int activityId) {
        GiftInfo giftInfo = giftInfoContext.getGiftInfo(subjectId, activityId);
        Assert.assertNotNull(giftInfo);
        return giftInfo;
    }
}

方案2：通过静态方法配置

public interface IGiftInfoStrategyService {

    GiftInfo getGiftInfo(int activityId);
}

/**
 * 双11活动
 */
@Service
public class DoubleElevenGiftInfoStrategyService implements IGiftInfoStrategyService {

    // 静态代码块中注册关联
    static {
        GiftInfoContext.registerProvider(2, DoubleElevenGiftInfoStrategyService.class);
    }

    @Override
    public GiftInfo getGiftInfo(int activityId) {
        // 双11调用统一平台接口获取礼品信息
        GiftInfo giftInfo = new GiftInfo();
        giftInfo.setGiftId(902);
        giftInfo.setGiftName("空气净化器");
        return giftInfo;
    }
}

/**
 * 夏季购车节
 */
@Service
public class SummerBuyDayGiftInfoStrategyService implements IGiftInfoStrategyService {

    // 静态代码块中注册关联
    static {
        GiftInfoContext.registerProvider(1, SummerBuyDayGiftInfoStrategyService.class);
    }

    @Resource
    private GiftInfoMapper giftInfoMapper;
    
    public GiftInfo getGiftInfo(int activityId) {
        // 从数据库中查询
        GiftInfo giftInfo = new GiftInfo();
        giftInfo.setGiftId(1);
        giftInfo.setGiftName("铁锅三件套");
        giftInfoMapper.getGiftInfoByActivityId(activityId)
        return giftInfo;
    }
}

/**
 * 礼品信息环境角色类
 */
@Component
public class GiftInfoContext {

    private static final Logger logger = LoggerFactory.getLogger(GiftInfoContext.class);

    // 策略映射map
    private static final Map<Integer, Class<?>> providers = new HashMap<>();

    // 提供给策略具体实现类的注册返回
    public static void registerProvider(int subjectId, Class<?> provider) {
        providers.put(subjectId, provider);
    }

    // 对外暴露的获取礼品信息接口返回
    public static GiftInfo getGiftInfo(int subjectId, int activityId) {
        Class<?> providerClazz = providers.get(subjectId);
        Assert.assertNotNull(providerClazz);
        Object bean = SpringUtils.getBean(providerClazz);
        Assert.assertNotNull(bean);
        if (bean instanceof IGiftInfoStrategyService) {
            IGiftInfoStrategyService strategyService = (IGiftInfoStrategyService) bean;
            return strategyService.getGiftInfo(activityId);
        }
        logger.error("Not Class with IGiftInfoListService: {}", providerClazz.getName());
        return null;
    }
}

public class GiftInfoTest {

    public GiftInfo getGiftInfo(int subjectId, int activityId) {
        GiftInfo giftInfo = GiftInfoContext.getGiftInfo(subjectId, activityId);
        Assert.assertNotNull(giftInfo);
        return giftInfo;
    }
}

方案3：通过spring自动注入list、map

对于@Resource声明的数组、集合类型，spring并不是根据beanName去找容器中对应的bean，而是把容器中所有类型与集合（数组）中元素类型相同的bean构造出一个对应集合，注入到目标bean中

public interface IGiftInfoStrategyService {

    GiftInfo getGiftInfo(int activityId);
     getTypeId();
}

/**
 * 夏季购车节
 */
@Service
public class SummerBuyDayGiftInfoStrategyService implements IGiftInfoStrategyService {

    @Resource
    private GiftInfoMapper giftInfoMapper;
    
    public GiftInfo getGiftInfo(int activityId) {
        // 从数据库中查询
        GiftInfo giftInfo = new GiftInfo();
        giftInfo.setGiftId(1);
        giftInfo.setGiftName("铁锅三件套");
        giftInfoMapper.getGiftInfoByActivityId(activityId)
        return giftInfo;
    }

     public int getTypeId() {
            return 1;
     }
}

/**
 * 双11活动
 */
@Service
public class DoubleElevenGiftInfoStrategyService implements IGiftInfoStrategyService {

    @Override
    public GiftInfo getGiftInfo(int activityId) {
        // 双11调用统一平台接口获取礼品信息
        GiftInfo giftInfo = new GiftInfo();
        giftInfo.setGiftId(902);
        giftInfo.setGiftName("空气净化器");
        return giftInfo;
    }

    public int getTypeId() {
            return 2;
     }
}

/**
 * 礼品信息环境角色类
 */
@Component
public class GiftInfoContext {

    // Spring自动注入
    @Resource
    private List<IGiftInfoStrategyService> giftInfoStrategyServiceList;

    // 对外暴露的统一获取礼品信息的返回
    public GiftInfo getGiftInfo(int subjectId, int activityId) {
          Optional<IGiftInfoStrategyService> optional = giftInfoStrategyServiceList.stream()
                                                  .filter(service -> service.getTypeId = subjectId)
                                                  .findFrist();
        if (!optional.isPresent()) {
                Assert.assertNotNull(giftInfoStrategyService);
        }
  
        return optional.get().getGiftInfo(activityId);
    }
}

/**
 * 礼品信息配置类
 */
@Configuration
public class GiftInfoConfig {

    @Resource
    private IGiftInfoStrategyService doubleElevenGiftInfoStrategyService;

    @Resource
    private IGiftInfoStrategyService summerBuyDayGiftInfoStrategyService;

    /**
     * 注入bean
     */
    @Bean
    public Map<Integer, IGiftInfoStrategyService> giftInfoStrategyServiceMap() {
        Map<Integer, IGiftInfoStrategyService> dataMap = new HashMap<>();
        dataMap.put(1, summerBuyDayGiftInfoStrategyService);
        dataMap.put(2, doubleElevenGiftInfoStrategyService);
        return dataMap;
    }
}

/**
 * 礼品信息调用
 */
public class GiftInfoTest {

    @Resource
    private GiftInfoContext giftInfoContext;

    public GiftInfo getGiftInfo(int subjectId, int activityId) {
        GiftInfo giftInfo = giftInfoContext.getGiftInfo(subjectId, activityId);
        Assert.assertNotNull(giftInfo);
        return giftInfo;
    }
}

Spring优雅的实现策略模式

源码

定义

算法结构

结构代码

项目实例

背景

方案1：通过spring配置注入策略

方案2：通过静态方法配置

方案3：通过spring自动注入list、map

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