结合工厂模式演进策略模式

src/main/java/top/fjy8018/designpattern/pattern/behavior/strategy/EmptyPromotionStrategy.java

@@ -0,0 +1,17 @@
+package top.fjy8018.designpattern.pattern.behavior.strategy;
+
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * 空策略
+ *
+ * @author F嘉阳
+ * @date 2020/3/4 16:16
+ */
+@Slf4j
+public class EmptyPromotionStrategy implements PromotionStrategy {
+    @Override
+    public void doPromotion() {
+        log.info("空促销策略");
+    }
+}

src/main/java/top/fjy8018/designpattern/pattern/behavior/strategy/PromotionStrategyFactory.java

@@ -0,0 +1,52 @@
+package top.fjy8018.designpattern.pattern.behavior.strategy;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * 促销策略工厂
+ *
+ * @author F嘉阳
+ * @date 2020/3/4 16:09
+ */
+public class PromotionStrategyFactory {
+
+    private static Map<String, PromotionStrategy> STRATEGY_MAP = new ConcurrentHashMap<>();
+
+    /**
+     * 无促销
+     */
+    private static final PromotionStrategy NON_PROMOTION = new EmptyPromotionStrategy();
+
+    static {
+        STRATEGY_MAP.put(PromotionKey.FANXIAN, new FanXianPromotionStrategy());
+        STRATEGY_MAP.put(PromotionKey.MANJIAN, new ManJianPromotionStrategy());
+        STRATEGY_MAP.put(PromotionKey.LIJIAN, new LiJianPromotionStrategy());
+    }
+
+    /**
+     * 禁止实例化
+     */
+    private PromotionStrategyFactory() {
+    }
+
+    /**
+     * 开放获取策略的方法
+     *
+     * @param promotionKey
+     * @return
+     */
+    public static PromotionStrategy getPromotionStrategy(String promotionKey) {
+        PromotionStrategy strategy = STRATEGY_MAP.get(promotionKey);
+        return strategy == null ? NON_PROMOTION : strategy;
+    }
+
+    /**
+     * 常量定义
+     */
+    private interface PromotionKey {
+        String LIJIAN = "LIJIAN";
+        String FANXIAN = "FANXIAN";
+        String MANJIAN = "MANJIAN";
+    }
+}

src/test/java/top/fjy8018/designpattern/pattern/behavior/strategy/PromotionStrategyTest.java

@@ -24,4 +24,11 @@ class PromotionStrategyTest {
 
         activity.executePromotionStrategy();
     }
+
+    @Test
+    void nonIfElse() {
+        String promotionKey = "LIJIAN";
+        PromotionActivity activity = new PromotionActivity(PromotionStrategyFactory.getPromotionStrategy(promotionKey));
+        activity.executePromotionStrategy();
+    }
 }