小傅哥 | 重学 Java 设计模式：实战策略模式「模拟多种营销类型优惠券，折扣金额计算策略场景」

.gitignore

@@ -34,3 +34,4 @@
 /itstack-demo-design-19-02/itstack-demo-design-19-02.iml
 /itstack-demo-design-19-01/itstack-demo-design-19-01.iml
 /itstack-demo-design-19-00/itstack-demo-design-19-00.iml
+/itstack-demo-design-20-01/itstack-demo-design-20-01.iml

itstack-demo-design-20-01/pom.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>itstack-demo-design</artifactId>
+        <groupId>org.itstack</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>itstack-demo-design-20-01</artifactId>
+
+
+</project>
\ No newline at end of file

itstack-demo-design-20-01/src/main/java/org/itstack/demo/design/CouponDiscountService.java

+package org.itstack.demo.design;
+
+import java.math.BigDecimal;
+
+/**
+ * 博客：https://bugstack.cn - 沉淀、分享、成长，让自己和他人都能有所收获！
+ * 公众号：bugstack虫洞栈
+ * Create by 小傅哥(fustack) @2020
+ * 优惠券折扣计算接口
+ * <p>
+ * 优惠券类型；
+ * 1. 直减券
+ * 2. 满减券
+ * 3. 折扣券
+ * 4. n元购
+ */
+public class CouponDiscountService {
+
+    public double discountAmount(int type, double typeContent, double skuPrice, double typeExt) {
+        // 1. 直减券
+        if (1 == type) {
+            return skuPrice - typeContent;
+        }
+        // 2. 满减券
+        if (2 == type) {
+            if (skuPrice < typeExt) return skuPrice;
+            return skuPrice - typeContent;
+        }
+        // 3. 折扣券
+        if (3 == type) {
+            return skuPrice * typeContent;
+        }
+        // 4. n元购
+        if (4 == type) {
+            return typeContent;
+        }
+        return 0D;
+    }
+
+}

itstack-demo-design-20-02/pom.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>itstack-demo-design</artifactId>
+        <groupId>org.itstack</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>itstack-demo-design-20-02</artifactId>
+
+
+</project>
\ No newline at end of file

itstack-demo-design-20-02/src/main/java/org/itstack/demo/design/Context.java

+package org.itstack.demo.design;
+
+import java.math.BigDecimal;
+
+/**
+ * 博客：https://bugstack.cn - 沉淀、分享、成长，让自己和他人都能有所收获！
+ * 公众号：bugstack虫洞栈
+ * Create by 小傅哥(fustack) @2020
+ */
+public class Context<T> {
+
+    private ICouponDiscount<T> couponDiscount;
+
+    public Context(ICouponDiscount<T> couponDiscount) {
+        this.couponDiscount = couponDiscount;
+    }
+
+    public BigDecimal discountAmount(T couponInfo, BigDecimal skuPrice) {
+        return couponDiscount.discountAmount(couponInfo, skuPrice);
+    }
+
+}

itstack-demo-design-20-02/src/main/java/org/itstack/demo/design/ICouponDiscount.java

+package org.itstack.demo.design;
+
+import java.math.BigDecimal;
+
+/**
+ * 博客：https://bugstack.cn - 沉淀、分享、成长，让自己和他人都能有所收获！
+ * 公众号：bugstack虫洞栈
+ * Create by 小傅哥(fustack) @2020
+ * <p>
+ * 优惠券折扣计算接口
+ * <p>
+ * 优惠券类型；
+ * 1. 直减券
+ * 2. 满减券
+ * 3. 折扣券
+ * 4. n元购
+ */
+public interface ICouponDiscount<T> {
+
+    /**
+     * 优惠券金额计算
+     * @param couponInfo 券折扣信息；直减、满减、折扣、N元购
+     * @param skuPrice   sku金额
+     * @return           优惠后金额
+     */
+    BigDecimal discountAmount(T couponInfo, BigDecimal skuPrice);
+
+}

itstack-demo-design-20-02/src/main/java/org/itstack/demo/design/impl/MJCouponDiscount.java

+package org.itstack.demo.design.impl;
+
+import org.itstack.demo.design.ICouponDiscount;
+
+import java.math.BigDecimal;
+import java.util.Map;
+
+/**
+ * 博客：https://bugstack.cn - 沉淀、分享、成长，让自己和他人都能有所收获！
+ * 公众号：bugstack虫洞栈
+ * Create by 小傅哥(fustack) @2020
+ *
+ * 满减
+ */
+public class MJCouponDiscount implements ICouponDiscount<Map<String,String>>  {
+
+    /**
+     * 满减计算
+     * 1. 判断满足x元后-n元，否则不减
+     * 2. 最低支付金额1元
+     */
+    public BigDecimal discountAmount(Map<String,String> couponInfo, BigDecimal skuPrice) {
+        String x = couponInfo.get("x");
+        String o = couponInfo.get("n");
+
+        // 小于商品金额条件的，直接返回商品原价
+        if (skuPrice.compareTo(new BigDecimal(x)) < 0) return skuPrice;
+        // 减去优惠金额判断
+        BigDecimal discountAmount = skuPrice.subtract(new BigDecimal(o));
+        if (discountAmount.compareTo(BigDecimal.ZERO) < 1) return BigDecimal.ONE;
+
+        return discountAmount;
+    }
+}

itstack-demo-design-20-02/src/main/java/org/itstack/demo/design/impl/NYGCouponDiscount.java

+package org.itstack.demo.design.impl;
+
+import org.itstack.demo.design.ICouponDiscount;
+
+import java.math.BigDecimal;
+
+/**
+ * 博客：https://bugstack.cn - 沉淀、分享、成长，让自己和他人都能有所收获！
+ * 公众号：bugstack虫洞栈
+ * Create by 小傅哥(fustack) @2020
+ *
+ * n元购买
+ */
+public class NYGCouponDiscount implements ICouponDiscount<Double> {
+
+    /**
+     * n元购购买
+     * 1. 无论原价多少钱都固定金额购买
+     */
+    public BigDecimal discountAmount(Double couponInfo, BigDecimal skuPrice) {
+        return new BigDecimal(couponInfo);
+    }
+
+}

itstack-demo-design-20-02/src/main/java/org/itstack/demo/design/impl/ZJCouponDiscount.java

+package org.itstack.demo.design.impl;
+
+import org.itstack.demo.design.ICouponDiscount;
+
+import java.math.BigDecimal;
+
+/**
+ * 博客：https://bugstack.cn - 沉淀、分享、成长，让自己和他人都能有所收获！
+ * 公众号：bugstack虫洞栈
+ * Create by 小傅哥(fustack) @2020
+ *
+ * 直减
+ */
+public class ZJCouponDiscount implements ICouponDiscount<Double>  {
+
+    /**
+     * 直减计算
+     * 1. 使用商品价格减去优惠价格
+     * 2. 最低支付金额1元
+     */
+    public BigDecimal discountAmount(Double couponInfo, BigDecimal skuPrice) {
+        BigDecimal discountAmount = skuPrice.subtract(new BigDecimal(couponInfo));
+        if (discountAmount.compareTo(BigDecimal.ZERO) < 1) return BigDecimal.ONE;
+        return discountAmount;
+    }
+
+}

itstack-demo-design-20-02/src/main/java/org/itstack/demo/design/impl/ZKCouponDiscount.java

+package org.itstack.demo.design.impl;
+
+import org.itstack.demo.design.ICouponDiscount;
+
+import java.math.BigDecimal;
+
+/**
+ * 博客：https://bugstack.cn - 沉淀、分享、成长，让自己和他人都能有所收获！
+ * 公众号：bugstack虫洞栈
+ * Create by 小傅哥(fustack) @2020
+ *
+ * 折扣
+ */
+public class ZKCouponDiscount implements ICouponDiscount<Double> {
+
+
+    /**
+     * 折扣计算
+     * 1. 使用商品价格乘以折扣比例，为最后支付金额
+     * 2. 保留两位小数
+     * 3. 最低支付金额1元
+     */
+    public BigDecimal discountAmount(Double couponInfo, BigDecimal skuPrice) {
+        BigDecimal discountAmount = skuPrice.multiply(new BigDecimal(couponInfo)).setScale(2, BigDecimal.ROUND_HALF_UP);
+        if (discountAmount.compareTo(BigDecimal.ZERO) < 1) return BigDecimal.ONE;
+        return discountAmount;
+    }
+
+}

itstack-demo-design-20-02/src/test/java/org/itstack/demo/design/test/ApiTest.java

+package org.itstack.demo.design.test;
+
+import org.itstack.demo.design.Context;
+import org.itstack.demo.design.impl.MJCouponDiscount;
+import org.itstack.demo.design.impl.NYGCouponDiscount;
+import org.itstack.demo.design.impl.ZJCouponDiscount;
+import org.itstack.demo.design.impl.ZKCouponDiscount;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.math.BigDecimal;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * 博客：https://bugstack.cn - 沉淀、分享、成长，让自己和他人都能有所收获！
+ * 公众号：bugstack虫洞栈
+ * Create by 小傅哥(fustack) @2020
+ */
+public class ApiTest {
+
+    private Logger logger = LoggerFactory.getLogger(ApiTest.class);
+
+    @Test
+    public void test_zj() {
+        // 直减；100-10，商品100元
+        Context<Double> context = new Context<Double>(new ZJCouponDiscount());
+        BigDecimal discountAmount = context.discountAmount(10D, new BigDecimal(100));
+        logger.info("测试结果：直减优惠后金额 {}", discountAmount);
+    }
+
+    @Test
+    public void test_mj() {
+        // 满100减10，商品100元
+        Context<Map<String,String>> context = new Context<Map<String,String>>(new MJCouponDiscount());
+        Map<String,String> mapReq = new HashMap<String, String>();
+        mapReq.put("x","100");
+        mapReq.put("n","10");
+        BigDecimal discountAmount = context.discountAmount(mapReq, new BigDecimal(100));
+        logger.info("测试结果：满减优惠后金额 {}", discountAmount);
+    }
+
+
+    @Test
+    public void test_zk() {
+        // 折扣9折，商品100元
+        Context<Double> context = new Context<Double>(new ZKCouponDiscount());
+        BigDecimal discountAmount = context.discountAmount(0.9D, new BigDecimal(100));
+        logger.info("测试结果：折扣9折后金额 {}", discountAmount);
+    }
+
+    @Test
+    public void test_nyg() {
+        // n元购；100-10，商品100元
+        Context<Double> context = new Context<Double>(new NYGCouponDiscount());
+        BigDecimal discountAmount = context.discountAmount(90D, new BigDecimal(100));
+        logger.info("测试结果：n元购优惠后金额 {}", discountAmount);
+    }
+
+}

pom.xml

@@ -55,6 +55,8 @@
         <module>itstack-demo-design-19-00</module>
         <module>itstack-demo-design-19-01</module>
         <module>itstack-demo-design-19-02</module>
+        <module>itstack-demo-design-20-01</module>
+        <module>itstack-demo-design-20-02</module>
     </modules>
 
     <dependencies>