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 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 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());
}
}
}