策略模式 + 反射工厂 很好的实现了开闭原则

应用场景：某天接到了一个需求，品牌给了一个第三方接口，例如：www.baidu.com,我们通过调用这个第三接口，会返回4种状态，ex:

String pageStatus = "pdpAdvertisePage";  代表我们经过一堆处理后要返回的是pdp广告页面

String pageStatus = "plpAdvertisePage";   代表我们经过一堆业务处理后要返回的是plp广告页面

String pageStatus = "shoppingCartAdvertisePage"; 代表我们经过一堆业务处理后要返回的是购物车广告页面

String pageStatus = "checkoutAdvertisePage"; 代表我们经过一堆业务处理后要返回的是购物车广告页面

期间的解决方案一：做了好多的判断 if elseif  elseif 写到后面我都不知道里面的判断逻辑是啥，太复杂了，果断放弃了

期间的解决方案二：利用了策略模式+简单工厂模式，总算把那些个if else给去掉了，逻辑算是比较清晰了

期间的解决方案三：利用策略模式+反射工厂，很完美的解决了简单工厂模式所带来的弊端 -- 实现了所谓的开闭原则

代码目录结构：

公共的接口： GetPointAdvertisePageStrategey.java

import org.springframework.ui.Model; /** * @author : David.liu * @description : 得到指定广告页面 * @creat :2019-05-26-22:02 */ public interface GetPointAdvertisePageStrategey { /** * 得到指定的页面 * @param itemRecommendParam * @param model * @return */ String getAdvertisePage(Model model); }

Ppd实现接口代码：PdpAdvertisePageStrategey.java

import org.springframework.stereotype.Component; import org.springframework.ui.Model; /** * @author : David.liu * @description : 得到pdp广告页面 * @creat :2019-05-26-22:05 */ @Component public class PdpAdvertisePageStrategey implements GetPointAdvertisePageStrategey{ /** * 得到指定的页面 * * @param itemRecommendParam * @param model * @return */ @Override public String getAdvertisePage() { return "pdp-advertise.jsp"; } }

Plp实现接口代码：PlpAdvertisePageStrategey.java

import org.springframework.stereotype.Component; import org.springframework.ui.Model; /** * @author : David.liu * @description : 得到指定的plp广告页面 * @creat :2019-05-26-22:07 */ @Component public class PlpAdvertisePageStrategey implements GetPointAdvertisePageStrategey { /** * 得到指定的plp广告页面 * * @param itemRecommendParam * @param model * @return */ @Override public String getAdvertisePage() { return "plp-advertise.jsp"; } } 购物车实现接口代码 ShopingCartAdvertisePageStrategey.java import org.springframework.stereotype.Component; import org.springframework.ui.Model; /** * @author : David.liu * @description : 得到购物车广告页面 * @creat :2019-05-26-22:10 */ @Component public class ShopingCartAdvertisePageStrategey implements GetPointAdvertisePageStrategey { /** * 得到指定的购物车页面 * * @param model * @return */ @Override public String getAdvertisePage() { return "shoppingcart-advertise.jsp"; } }

结算实现接口代码：CheckoutAdvertisePageStrategey.java

import org.springframework.stereotype.Component; import org.springframework.ui.Model; /** * @author : David.liu * @description : 得到结算页面广告页面 * @creat :2019-05-26-22:12 */ @Component public class CheckoutAdvertisePageStrategey implements GetPointAdvertisePageStrategey { /** * 得到指定的结算页面 * * @param itemRecommendParam * @param model * @return */ @Override public String getAdvertisePage() { return "checkout-advertise.jsp"; } }

生产广告页面。简单工厂类 GetPointAdvertisePageReflectFactory.java，案例未使用，但代码贴出来了，供读者对比两个的差异，感受一下，开闭原则，对比一下，简单工厂和反射工厂的不同。

思考角度，如果需求在加一个策略类，2个、3个？ 那么你就感受到了

import com.feilong.core.Validator; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; import java.util.HashMap; import java.util.Map; /** * @author : David.liu * @description : 生产广告页面简单工厂 * @creat :2019-05-26-22:14 */ @Component public class GetPointAdvertisePageSimpleFactory { public static final String PDP_ITEM_ADVERTISE = "PDP_ITEM_ADVERTISE"; public static final String PLP_ITEM_ADVERTISE = "PLP_ITEM_ADVERTISE"; public static final String CHECKOUT_ITEM_ADVERTISE = "CHECKOUT_ITEM_ADVERTISE"; public static final String SHOPPINGCART_ITEM_ADVERTISE = "SHOPPINGCART_ITEM_ADVERTISE"; private static Map<String, GetPointAdvertisePageStrategey> recommendStrategyMap = new HashMap<>(); @Autowired private CheckoutAdvertisePageStrategey checkoutAdvertisePageStrategey; @Autowired private PdpAdvertisePageStrategey pdpAdvertisePageStrategey; @Autowired private PlpAdvertisePageStrategey plpAdvertisePageStrategey; @Autowired private ShopingCartAdvertisePageStrategey shopingCartAdvertisePageStrategey; /** 初始化所有的策略类 */ protected void init(){ recommendStrategyMap.put(PDP_ITEM_ADVERTISE, pdpAdvertisePageStrategey); recommendStrategyMap.put(PLP_ITEM_ADVERTISE,plpAdvertisePageStrategey ); recommendStrategyMap.put(CHECKOUT_ITEM_ADVERTISE, checkoutAdvertisePageStrategey); recommendStrategyMap.put(SHOPPINGCART_ITEM_ADVERTISE,shopingCartAdvertisePageStrategey ); } /** 根据pageType 得到指定的处理类 */ public GetPointAdvertisePageStrategey getStrategey(String pageType) { if(Validator.isNullOrEmpty(recommendStrategyMap)){ init(); } return recommendStrategyMap.get(pageType); } }

 

生产广告页面。反射工厂类 GetPointAdvertisePageReflectFactory.java

import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.config.AutowireCapableBeanFactory; import org.springframework.context.ApplicationContext; import org.springframework.stereotype.Component; /** * @author : David.liu * @description : 生产广告页面反射工厂 * @creat :2019-05-26-22:15 */ @Component public class GetPointAdvertisePageReflectFactory { @Autowired private ApplicationContext context; private static final Logger LOGGER = LoggerFactory.getLogger(GetPointAdvertisePageReflectFactory.class); // 通过配置文件名：filePathName 和 文件中的key 得到指定的类 public GetPointAdvertisePageStrategey getAdvertisePageStrategey(String filePathName, String key){ GetPointAdvertisePageStrategey getPointAdvertisePageStrategey = null; String classPath = null; try { classPath = PropertyUtil.get(filePathName,key); if(Validator.isNullOrEmpty(classPath)) return null; //通过反射创建对象 Class<?> handler = Class.forName(classPath); //这里必须强行纳入spring管理，否则在得到的具体实现类中，如果有通过@Autowired注入的bean，将会报注入失败 getPointAdvertisePageStrategey = (GetPointAdvertisePageStrategey) context.getAutowireCapableBeanFactory().createBean(handler, AutowireCapableBeanFactory.AUTOWIRE_BY_TYPE, true); } catch (Exception e) { LOGGER.error("Failed to reflect the corresponding object through the specified path，filePath:{},key:{}",filePathName,key); return null; } return getPointAdvertisePageStrategey; } }

文件读取工具类: PropertyUtil.java

import com.feilong.core.Validator; import java.io.IOException; import java.io.InputStream; import java.util.HashMap; import java.util.Map; import java.util.Properties; /** * 获取配置文件参数工具类 * 拥有缓存功能，当查询了某个文件时会自动缓存 * @author wei.liu5 * @Date 2019/5/20 */ public class PropertyUtil { private static Map<String, Properties> cache = new HashMap<>(); /** * * @param configFileName 配置文件名 * @param key 配置文件中的 key=value 中的key * @return */ public static String get(String configFileName,String key){ return getProperties(configFileName).getProperty(key); } public static Properties getProperties(String configFileName) { if (Validator.isNotNullOrEmpty(cache.get(configFileName))) { return cache.get(configFileName); } InputStream inputStream = PropertyUtil.class.getResourceAsStream(configFileName); Properties properties = new Properties(); try { properties.load(inputStream); } catch (IOException e) { e.printStackTrace(); } cache.put(configFileName,properties); return properties; } }

配置文件：itemrecommend.properties

# 下面是每个实现类的具体路径，利用反射的原理来达到获取某个具体类的目的 pdp.item.advertise=com.wy.store.web.manager.PdpAdvertisePageStrategey plp.item.advertise=com.wy.store.web.manager.PlpAdvertisePageStrategey shoppingcart.item.advertise=com.wy.store.web.manager.ShopingCartAdvertisePageStrategey checkout.item.advertise=com.wy.store.web.manager.CheckoutAdvertisePageStrategey

测试类：测试代码用的是 策略模式+反射工厂，这里未使用简单工厂，但代码也贴出来了

import com.feilong.core.Validator; import org.junit.Test; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; public class ItemRecommendReflectFactoryTest { private static final Logger LOGGER = LoggerFactory.getLogger(ItemRecommendReflectFactoryTest.class); @Autowired private GetPointAdvertisePageReflectFactory getItemRecommendStrategey; @Test public void refectFactoryTest(){ String path = "/itemrecommend.properties"; GetPointAdvertisePageStrategey getPointAdvertisePageStrategey = getItemRecommendStrategey.getAdvertisePageStrategey(path,"pdp.item.advertise"); if(Validator.isNotNullOrEmpty(getPointAdvertisePageStrategey)){ LOGGER.info("通过配置文件和反射机制，在运行时动态获取指定的执行类，测试成功"); LOGGER.info(getPointAdvertisePageStrategey.getAdvertisePage()); } } }