一个考设计模式的编程题（A、B、C公司优惠策略）

大厂鄙视题，如下（鄙人斗胆一写，如有误导欢迎沟通指正）

image.png

话不多说，直接上代码吧

封装枚举

interface CustomerType {
    // 获取折扣
    Double getDiscount();
    // 根据 用户类型code获取 实例
    static CustomerType getDiscountBy(String code, CustomerType[] values) {
        for (CustomerType value : values) {
            if(value.getCode().equals(code))
                return value;
        }
        throw new IllegalArgumentException("参数不合法");
    }
    String getCode();
}
enum ECustomerType_A implements CustomerType {
    SUPER_VIP("超级VIP用户", "A001", 0.7),
    VIP("VIP用户", "A002", 0.9),
    NORMAL("普通用户", "A003", 1.0),
    ;
    private String desc;
    private String code;
    private Double discount;

    ECustomerType_A(String desc, String code, Double discount) {
        this.desc = desc;
        this.code = code;
        this.discount = discount;
    }
    public String getDesc() {
        return desc;
    }
    @Override
    public String getCode() {
        return code;
    }
    @Override
    public Double getDiscount() {
        return discount;
    }
}
enum ECustomerType_B implements CustomerType {
    JP("金牌", "B001", 0.65),
    YP("银牌", "B002", 0.75),
    TP("铜牌用户", "B003", 0.85),
    NORMAL("普通用户", "B004", 1.0),
    ;
    private String desc;
    private String code;
    private Double discount;
    ECustomerType_B(String desc, String code, Double discount) {
        this.desc = desc;
        this.code = code;
        this.discount = discount;
    }
    public String getDesc() {
        return desc;
    }
    @Override
    public String getCode() {
        return code;
    }
    @Override
    public Double getDiscount() {
        return discount;
    }
}
enum ECustomerType_C implements CustomerType {
    HGHY("皇冠", "C001", 0.8),
    NORMAL("普通用户", "C002", 1.0),
    ;
    private String desc;
    private String code;
    private Double discount;
    ECustomerType_C(String desc, String code, Double discount) {
        this.desc = desc;
        this.code = code;
        this.discount = discount;
    }
    public String getDesc() {
        return desc;
    }
    @Override
    public String getCode() {
        return code;
    }
    @Override
    public Double getDiscount() {
        return discount;
    }
}

定义公司接口及编写具体实现

public interface Company {
    Double getDiscount(String code);
}
class CompanyA implements Company {
    @Override
    public Double getDiscount(String code) {
        CustomerType discountBy = CustomerType.getDiscountBy(code, ECustomerType_A.values());
        Double discount = discountBy.getDiscount();
        return discount;
    }
}
class CompanyB implements Company {
    @Override
    public Double getDiscount(String code) {
        CustomerType discountBy = CustomerType.getDiscountBy(code, ECustomerType_B.values());
        Double discount = discountBy.getDiscount();
        return discount;
    }
}
class CompanyC implements Company {
    @Override
    public Double getDiscount(String code) {
        CustomerType discountBy = CustomerType.getDiscountBy(code, ECustomerType_C.values());
        Double discount = discountBy.getDiscount();
        return discount;
    }
}

业务层具体使用代码

// 业务方直接使用的接口
interface CompanyPrice {
    // 根据公司类型、用户类型、原价格 获取 现在价格
    Double get(String companyName, String userType, Double price);
}
class CompanyPriceImpl implements CompanyPrice {
    private static HashMap companyHashMap = new HashMap<>();
    static {
        companyHashMap.put("A",new CompanyA());
        companyHashMap.put("B",new CompanyB());
        companyHashMap.put("C",new CompanyC());
    }
    // 参数说明：公司类型（A、B、C）、用户类型code、价格
    // 公司类型、用户类型code可以进一步用枚举规范，略...
    @Override
    public Double get(String companyName, String userTypeCode, Double price) {
        Company company = companyHashMap.get(companyName);
        if(company == null){
            throw new IllegalArgumentException("参数不合法");
        }
        Double discount = company.getDiscount(userTypeCode);
        BigDecimal oldPrice = new BigDecimal(price.toString());
        BigDecimal discountBigD = new BigDecimal(discount.toString());
        BigDecimal multiply = oldPrice.multiply(discountBigD);
        Double newPrice = multiply.doubleValue();
        return newPrice;
    }
}