Spring高級特性-多種類會員折扣問題

解決問題：當有多種類型的會員時，訂單計費的價格是有差異的，代碼中太多的if和else必然導致代碼的臃腫和難以維護，其實可以優雅的設計它。

1、定以訂單類

@Service
@Slf4j
public class OrderServiceImpl implements OrderService {
    //自動注入一個map(key是託管給Spring管理的引用名稱，value爲真實對象)
    @Autowired
    private Map<String, CalculateAmountService> calculateAmountServiceMap;

    @Autowired
    private ApplicationContext applicationContext;

    @Override
    public double getPaymentAmount(String userType, double amount) {
        log.debug("所有的折扣對象：{}", calculateAmountServiceMap);
        //根據用戶的類型從map對象中找到對應的對象進行金額的計算
        CalculateAmountService service = calculateAmountServiceMap.get(userType);
        if (Objects.isNull(service)) {
            return amount;
        }
        return service.getPaymentAmountByDisCount(amount);
    }
}

2、定義不同用戶類型計算的基類

package com.milla.navicat.spring.study.service;

/**
 * @Package: com.milla.navicat.spring.study.service
 * @Description: <根據不同的折扣計算不同的金額>
 * @Author: MILLA
 * @CreateDate: 2019/11/1 16:58
 * @UpdateUser: MILLA
 * @UpdateDate: 2019/11/1 16:58
 * @UpdateRemark: <>
 * @Version: 1.0
 */
public interface CalculateAmountService {
    //根據用戶的類型打折
    double getPaymentAmountByDisCount(double fee);
}

3、具體實現類

3.1、普通會員實現類

package com.milla.navicat.spring.study.service.impl;

import com.milla.navicat.spring.study.service.CalculateAmountService;
import org.springframework.stereotype.Service;

/**
 * @Package: com.milla.navicat.spring.study.service.impl
 * @Description: <會員折扣>
 * @Author: MILLA
 * @CreateDate: 2019/11/1 16:59
 * @UpdateUser: MILLA
 * @UpdateDate: 2019/11/1 16:59
 * @UpdateRemark: <>
 * @Version: 1.0
 */
@Service(value = "normal")//託管處理時的引用名稱
public class NormalCalculateAmountServiceImpl implements CalculateAmountService {

    @Override
    public double getPaymentAmountByDisCount(double fee) {
        return fee * 0.9;
    }
}

3.2、VIP會員實現類

package com.milla.navicat.spring.study.service.impl;

import com.milla.navicat.spring.study.service.CalculateAmountService;
import org.springframework.stereotype.Service;

/**
 * @Package: com.milla.navicat.spring.study.service.impl
 * @Description: <會員折扣>
 * @Author: MILLA
 * @CreateDate: 2019/11/1 16:59
 * @UpdateUser: MILLA
 * @UpdateDate: 2019/11/1 16:59
 * @UpdateRemark: <>
 * @Version: 1.0
 */
@Service(value = "vip")
public class VIPCalculateAmountServiceImpl implements CalculateAmountService {

    @Override
    public double getPaymentAmountByDisCount(double fee) {
        return fee * 0.8;
    }
}

3.3、金卡會員實現類

package com.milla.navicat.spring.study.service.impl;

import com.milla.navicat.spring.study.service.CalculateAmountService;
import org.springframework.stereotype.Service;

/**
 * @Package: com.milla.navicat.spring.study.service.impl
 * @Description: <至尊會員折扣>
 * @Author: MILLA
 * @CreateDate: 2019/11/1 16:59
 * @UpdateUser: MILLA
 * @UpdateDate: 2019/11/1 16:59
 * @UpdateRemark: <>
 * @Version: 1.0
 */
@Service(value = "gold")
public class GoldCalculateAmountServiceImpl implements CalculateAmountService {

    @Override
    public double getPaymentAmountByDisCount(double fee) {
        return fee * 0.55;
    }
}

3.4、超級會員實現類

package com.milla.navicat.spring.study.service.impl;

import com.milla.navicat.spring.study.service.CalculateAmountService;
import org.springframework.stereotype.Service;

/**
 * @Package: com.milla.navicat.spring.study.service.impl
 * @Description: <超級會員折扣>
 * @Author: MILLA
 * @CreateDate: 2019/11/1 16:59
 * @UpdateUser: MILLA
 * @UpdateDate: 2019/11/1 16:59
 * @UpdateRemark: <>
 * @Version: 1.0
 */
@Service(value = "svip")
public class SVIPCalculateAmountServiceImpl implements CalculateAmountService {

    @Override
    public double getPaymentAmountByDisCount(double fee) {
        return fee * 0.5;
    }
}

4、測試類

@RunWith(SpringRunner.class)
@SpringBootTest
@Slf4j
public class MyNavicatApplicationTests { 
@Test
    public void testDiscountByUserType() {
        log.info("youke  類型的折扣：{}", saleService.getPaymentAmount("youke", 100));
        log.info("normal 類型的折扣：{}", saleService.getPaymentAmount("normal", 100));
        log.info("vip 類型的折扣：{}", saleService.getPaymentAmount("vip", 100));
        log.info("svip 類型的折扣：{}", saleService.getPaymentAmount("svip", 100));
        log.info("gold 類型的折扣：{}", saleService.getPaymentAmount("gold", 100));
    }
}