ISDP010_基于DDD架构实现收银用例主成功场景

信息系统开发实践｜系列文章传送门
ISDP001_课程概述
ISDP002_Maven上_创建Maven项目
ISDP003_Maven下_Maven项目依赖配置
ISDP004_创建SpringBoot3项目
ISDP005_Spring组件与自动装配
ISDP006_逻辑架构设计
ISDP007_Springboot日志配置与单元测试
ISDP008_SpringBoot Controller接口文档与测试
ISDP009_基于DDD架构设计ISDP的处理销售用例
ISDP010_基于DDD架构实现收银用例主成功场景

1 面向DDD重构mis-pos模块

重要说明：由于代码量增加，且经常需要重构。笔记将难以展示项目完整代码。本章笔记开始只展示部分代码。完整代码详见笔记最后项目仓库分支代码。

参考上篇分析与设计制品，参考DDD架构，重构的mis-pos模块的架构分层。

根据DDD架构分为application、domain、infrastructure三个包。
在这里插入图片描述

2 基础设施层

基础设施层暂时还没有写太多的类。只是添加了SaleFactory用于实例化Sale。

引入Hutool工具类，用于生成订单的雪花ID。

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.8.20</version>
        </dependency>

编写SaleFactory，实例化Sale并设置初始化值。

package edu.scau.mis.pos.infrastructure.factory;

import cn.hutool.core.util.IdUtil;
import edu.scau.mis.pos.domain.entity.Sale;
import edu.scau.mis.pos.domain.enums.SaleStatusEnum;
import org.springframework.stereotype.Component;

import java.math.BigDecimal;
import java.util.Date;

/**
 * Sale工厂类
 */
@Component
public class SaleFactory {
    public Sale initSale()
    {
        Sale sale = new Sale();
        sale.setSaleNo("so-" + IdUtil.getSnowflakeNextId());
        sale.setSaleStatus(SaleStatusEnum.CREATED);
        sale.setTotalAmount(BigDecimal.ZERO);
        sale.setTotalQuantity(0);
        sale.setSaleTime(new Date());
        return sale;
    }

}

3 领域层

在DDD架构中，领域层是重点关注层。

为了简化Setter和getter编写，引入了Lombok。

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

3.1 SaleProduct实体类

SaleProduct实体类包含了业务逻辑方法getSubTotal，计算每个订单明细的小计。

package edu.scau.mis.pos.domain.entity;

import edu.scau.mis.pos.domain.enums.SaleProductStatusEnum;
import lombok.Data;

import java.math.BigDecimal;

/**
 * 订单-产品明细实体类
 */
@Data
public class SaleProduct {
    private Long saleProductId;

    private Long saleId;

    private Long productId;

    private Product product;

    private Integer saleQuantity;

    private BigDecimal salePrice;

    private SaleProductStatusEnum saleProductStatus;

    /**
     * 计算小计
     * @return
     */
    public BigDecimal getSubTotal() {
        return salePrice.multiply(new BigDecimal(saleQuantity));
    }
}

3.2 支付实体类

支付类暂时还没有写业务逻辑方法。后期考虑通过适配器，连接第三方支付。

package edu.scau.mis.pos.domain.entity;

import com.fasterxml.jackson.annotation.JsonFormat;
import edu.scau.mis.pos.domain.enums.PaymentStatusEnum;
import edu.scau.mis.pos.domain.enums.PaymentStrategyEnum;
import lombok.Data;

import java.math.BigDecimal;
import java.util.Date;

/**
 * 支付实体类
 */
@Data
public class Payment {
    private Long paymentId;
    private Long paymentSaleId;
    private PaymentStrategyEnum paymentStrategy;
    private String paymentNo;
    private BigDecimal paymentAmount;
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private Date paymentTime;
    private PaymentStatusEnum paymentStatus;

}

3.3 Sale聚合根

Sale类是收银领域层的聚合根。

该类内聚了两个业务逻辑方法，分别为添加订单明细和计算总金额。

package edu.scau.mis.pos.domain.entity;

import com.fasterxml.jackson.annotation.JsonFormat;
import edu.scau.mis.pos.domain.enums.SaleStatusEnum;
import lombok.Data;

import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * 销售实体类
 * 聚合根
 */
@Data
public class Sale {
    private Long saleId;
    private String saleNo;
    private BigDecimal totalAmount;
    private Integer totalQuantity;
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private Date saleTime;
    private Payment payment;
    private List<SaleProduct> saleProducts = new ArrayList<>();
    private SaleStatusEnum saleStatus;

    /**
     * 计算总金额
     * @return
     */

    public BigDecimal getTotal(){
        totalAmount = BigDecimal.ZERO;
        totalQuantity = 0;
        for(SaleProduct saleProduct: saleProducts){
            totalAmount = totalAmount.add(saleProduct.getSubTotal());
            totalQuantity = totalQuantity + saleProduct.getSaleQuantity();
        }
        return totalAmount;
    }

    /**
     * 添加订单明细
     * @param product
     * @param saleQuantity
     * @return
     */

    public List<SaleProduct> makeLineItem(Product product, Integer saleQuantity) {
        // 判断商品是否已录入，未录入则新增。已录入则修改数量。
        if(!isEntered(product.getProductSn(),saleQuantity)){
            SaleProduct saleProduct = new SaleProduct();
            saleProduct.setProduct(product);
            saleProduct.setSaleQuantity(saleQuantity);
            saleProduct.setSalePrice(product.getProductPrice());
            saleProducts.add(saleProduct);
        }
        return saleProducts;
    }

    /**
     * 判断商品是否已录入
     * 业务逻辑：如果已录入，则修改数量，否则添加saleLineItem
     * @param productSn
     * @param saleQuantity
     * @return
     */
    private boolean isEntered(String productSn, Integer saleQuantity){
        boolean flag = false;
        for(SaleProduct sp : saleProducts){
            if(productSn.equals(sp.getProduct().getProductSn())) {
                flag = true;
                Integer quantityOriginal = sp.getSaleQuantity();
                sp.setSaleQuantity(quantityOriginal + saleQuantity);
            }
        }
        return flag;
    }
}

3.4 领域服务类SaleService

主要用于生成支付功能。ISDP项目POS系统设计支持挂单功能。

package edu.scau.mis.pos.domain.service.impl;

import cn.hutool.core.util.IdUtil;
import edu.scau.mis.pos.domain.entity.Payment;
import edu.scau.mis.pos.domain.entity.Sale;
import edu.scau.mis.pos.domain.enums.PaymentStatusEnum;
import edu.scau.mis.pos.domain.enums.PaymentStrategyEnum;
import edu.scau.mis.pos.domain.service.ISaleService;
import org.springframework.stereotype.Service;

import java.math.BigDecimal;
import java.util.Date;

/**
 * 领域服务
 */
@Service
public class SaleServiceImpl implements ISaleService {
    @Override
    public Payment makePayment(Sale sale, String paymentStrategy, BigDecimal paymentAmount) {
        Payment payment = new Payment();
        payment.setPaymentStrategy(PaymentStrategyEnum.valueOf(paymentStrategy));
        payment.setPaymentNo(paymentStrategy + "-" + IdUtil.getSnowflakeNextId());
        payment.setPaymentAmount(paymentAmount);
        payment.setPaymentTime(new Date());
        payment.setPaymentStatus(PaymentStatusEnum.PAID);
        // TODO: 根据不同支付策略调用不同外部接口
        return payment;
    }
}

3.5 其他

Domain层还有仓库、枚举等包。由于暂时还没有使用数据库和Redis，仓库代码暂时没写。

写了一些枚举类。由于只是教学项目，没有设计过多状态。

package edu.scau.mis.pos.domain.enums;

/**
 * 订单状态枚举
 */
public enum SaleStatusEnum {
    CREATED("0","已预订"),

    SUBMITTED("1","已提交"),

    PAID("2","已支付");

    private String value;

    private String label;

    SaleStatusEnum(String value, String label) {
        this.value = value;
        this.label = label;
    }

    public String getLabel() {
        return label;
    }

    public String getValue() {
        return value;
    }

    /**
     * 根据匹配value的值获取Label
     *
     * @param value
     * @return
     */
    public static String getLabelByValue(String value){
        for (SaleStatusEnum s : SaleStatusEnum.values()) {
            if(value.equals(s.getValue())){
                return s.getLabel();
            }
        }
        return "";
    }

    /**
     * 获取StatusEnum
     *
     * @param value
     * @return
     */
    public static SaleStatusEnum getStatusEnum(String value){
        for (SaleStatusEnum s : SaleStatusEnum.values()) {
            if(value.equals(s.getValue())){
                return s;
            }
        }
        return null;
    }
}

支付策略枚举类

package edu.scau.mis.pos.domain.enums;

/**
 * 支付策略枚举
 */
public enum PaymentStrategyEnum {
    WECHAT("wechat","微信支付"),

    ALIPAY("alipay","支付宝"),

    CASH("cash","现金");

    private String value;

    private String label;

    PaymentStrategyEnum(String value, String label) {
        this.value = value;
        this.label = label;
    }

    public String getLabel() {
        return label;
    }

    public String getValue() {
        return value;
    }

    /**
     * 根据匹配value的值获取Label
     *
     * @param value
     * @return
     */
    public static String getLabelByValue(String value){
        for (PaymentStrategyEnum s : PaymentStrategyEnum.values()) {
            if(value.equals(s.getValue())){
                return s.getLabel();
            }
        }
        return "";
    }

    /**
     * 获取StatusEnum
     *
     * @param value
     * @return
     */
    public static PaymentStrategyEnum getStrategyEnum(String value){
        for (PaymentStrategyEnum s : PaymentStrategyEnum.values()) {
            if(value.equals(s.getValue())){
                return s;
            }
        }
        return null;
    }
}

4 应用层

4.1 应用服务类SaleApplicationService

编写SaleApplicationService类。该类主要负责跨领域协作。

目前主要就两个领域Sale（SaleProduct、Payment）和Product（Category）。

如果使用微服务，可以分别针对这两个领域创建两个微服务模块。

package edu.scau.mis.pos.application.service;

import edu.scau.mis.pos.application.assembler.SaleAssembler;
import edu.scau.mis.pos.application.dto.command.EnterItemCommand;
import edu.scau.mis.pos.application.dto.command.MakePaymentCommand;
import edu.scau.mis.pos.application.dto.vo.*;
import edu.scau.mis.pos.domain.entity.Payment;
import edu.scau.mis.pos.domain.entity.Product;
import edu.scau.mis.pos.domain.entity.Sale;
import edu.scau.mis.pos.domain.entity.SaleProduct;
import edu.scau.mis.pos.domain.enums.SaleStatusEnum;
import edu.scau.mis.pos.domain.service.IProductService;
import edu.scau.mis.pos.infrastructure.factory.SaleFactory;
import edu.scau.mis.pos.domain.service.ISaleService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class SaleApplicationService {
    @Autowired
    private IProductService productService;

    @Autowired
    private ISaleService saleService;

    @Autowired
    private SaleFactory saleFactory;

    @Autowired
    private SaleAssembler saleAssembler;

    private Sale currentSale; // 后期改成Redis缓存CurrentSale

    /**
     * 开始一次新销售
     * @return
     */
    public SaleVo makeNewSale(){
        SaleVo saleVo = new SaleVo();
        currentSale = saleFactory.initSale();
        // TODO：引入Redis缓存
        return saleAssembler.toSaleVo(currentSale);
    }

    /**
     * 录入商品
     * @param command
     * @return
     */
    public SaleAndProductListVo enterItem(EnterItemCommand command){
        SaleAndProductListVo saleAndProductListVo = new SaleAndProductListVo();
        Product product = productService.selectProductBySn(command.getProductSn());
        List<SaleProduct> saleProducts = currentSale.makeLineItem(product, command.getSaleQuantity());
        currentSale.getTotal();
        List<SaleProductVo> saleProductVoList = saleProducts.stream()
                .map(saleProduct -> new SaleProductVo(saleProduct.getProduct().getProductSn(), saleProduct.getProduct().getProductName(), saleProduct.getSalePrice(), saleProduct.getSaleQuantity()))
                .toList();
        saleAndProductListVo.setSaleVo(saleAssembler.toSaleVo(currentSale));
        saleAndProductListVo.setSaleProductVoList(saleProductVoList);
        return saleAndProductListVo;
    }

    /**
     * 结束销售
     * 计算优惠、持久化订单等
     * @return
     */
    public SaleVo endSale(){
        currentSale.setSaleStatus(SaleStatusEnum.SUBMITTED);
        // TODO: 持久化Sale和SaleProduct，添加事务注解
        return saleAssembler.toSaleVo(currentSale);
    }

    /**
     * 完成支付
     * @param command
     * @return
     */
    public SaleAndPaymentVo makePayment(MakePaymentCommand command){
        SaleAndPaymentVo saleAndPaymentVo = new SaleAndPaymentVo();
        // TODO: 挂单--根据saleNo获取Sale
        Payment payment = saleService.makePayment(currentSale,command.getPaymentStrategy(), command.getPaymentAmount());
        currentSale.setPayment(payment);
        currentSale.setSaleStatus(SaleStatusEnum.PAID);
        // TODO： 持久化Sale和Payment，添加事务注解
        // payment.setPaymentSaleId(sale.getSaleId());
        saleAndPaymentVo.setSaleVo(saleAssembler.toSaleVo(currentSale));
        saleAndPaymentVo.setPaymentVo(saleAssembler.toPaymentVo(payment));
        return saleAndPaymentVo;
    }
}

4.2 数据传输对象DTO

ISDP项目采用CQRS思想，该层编写大量的数据传输对象DTO。笔记只展示部分代码。详细参加项目仓库。

EnterItemCommand参考代码如下。

后期将使用Redis缓存currentSale，设计saleNo作为key。保留saleNo备用。

package edu.scau.mis.pos.application.dto.command;

import lombok.Data;

import java.io.Serializable;

/**
 * 输入订单明细命令
 */
@Data
public class EnterItemCommand implements Serializable {
    private String saleNo;

    private String productSn;

    private Integer saleQuantity;
}

MakePaymentCommand代码参考如下：

同上，saleNo暂时不需要。

package edu.scau.mis.pos.application.dto.command;

import lombok.Data;

import java.io.Serializable;
import java.math.BigDecimal;

/**
 * 创建支付命令
 */
@Data
public class MakePaymentCommand implements Serializable {
    private String saleNo;
    private BigDecimal paymentAmount;
    private String paymentStrategy;
}

SaleVo类

package edu.scau.mis.pos.application.dto.vo;

import lombok.Data;

import java.io.Serializable;
import java.math.BigDecimal;
import java.util.Date;
@Data
public class SaleVo implements Serializable {
    private String saleNo;
    private BigDecimal totalAmount;
    private Integer totalQuantity;
    private Date saleTime;
    private String saleStatus;
}

SaleAndPaymentVo

package edu.scau.mis.pos.application.dto.vo;

import lombok.Data;

import java.io.Serializable;
@Data
public class SaleAndPaymentVo implements Serializable {
    private SaleVo saleVo;
    private PaymentVo paymentVo;
}

4.3 对象转换器SaleAssembler

面向接口层主要使用DTO对象，因此不可避免涉及到DTO与领域对象的转换。

package edu.scau.mis.pos.application.assembler;

import edu.scau.mis.pos.application.dto.vo.PaymentVo;
import edu.scau.mis.pos.application.dto.vo.SaleVo;
import edu.scau.mis.pos.domain.entity.Payment;
import edu.scau.mis.pos.domain.entity.Sale;
import org.springframework.stereotype.Component;

/**
 * 订单转换器
 * 实现DTO与Entity的转换
 */

@Component
public class SaleAssembler {
    public SaleVo toSaleVo(Sale sale){
        SaleVo saleVo = new SaleVo();
        saleVo.setSaleNo(sale.getSaleNo());
        saleVo.setTotalAmount(sale.getTotalAmount());
        saleVo.setTotalQuantity(sale.getTotalQuantity());
        saleVo.setSaleTime(sale.getSaleTime());
        saleVo.setSaleStatus(sale.getSaleStatus().getLabel());
        return saleVo;
    }

    public PaymentVo toPaymentVo(Payment payment){
        PaymentVo paymentVo = new PaymentVo();
        paymentVo.setPaymentId(payment.getPaymentId());
        paymentVo.setPaymentSaleId(payment.getPaymentSaleId());
        paymentVo.setPaymentNo(payment.getPaymentNo());
        paymentVo.setPaymentAmount(payment.getPaymentAmount());
        paymentVo.setPaymentTime(payment.getPaymentTime());
        paymentVo.setPaymentStrategy(payment.getPaymentStrategy().getLabel());
        paymentVo.setPaymentStatus(payment.getPaymentStatus().getLabel());
        return paymentVo;
    }
}

5 接口层

5.1 Controller接口

SaleController参考如下：

package edu.scau.mis.web.controller;

import edu.scau.mis.pos.application.dto.command.EnterItemCommand;
import edu.scau.mis.pos.application.dto.command.MakePaymentCommand;
import edu.scau.mis.pos.application.dto.vo.SaleAndPaymentVo;
import edu.scau.mis.pos.application.dto.vo.SaleAndProductListVo;
import edu.scau.mis.pos.application.dto.vo.SaleVo;
import edu.scau.mis.pos.application.service.SaleApplicationService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/sale")
public class SaleController {
    @Autowired
    private SaleApplicationService saleApplicationService;
    @GetMapping("/makeNewSale")
    public ResponseEntity<SaleVo> makeNewSale()
    {
        return ResponseEntity.ok(saleApplicationService.makeNewSale());
    }

    @PostMapping("/enterItem")
    public ResponseEntity<SaleAndProductListVo> enterItem(@RequestBody  EnterItemCommand enterItemCommand)
    {
        return ResponseEntity.ok(saleApplicationService.enterItem(enterItemCommand));
    }

    @GetMapping("/endSale")
    public ResponseEntity<SaleVo> endSale()
    {
        return ResponseEntity.ok(saleApplicationService.endSale());
    }

    @PostMapping("/makePayment")
    public ResponseEntity<SaleAndPaymentVo> makePayment(@RequestBody MakePaymentCommand makePaymentCommand)
    {
        return ResponseEntity.ok(saleApplicationService.makePayment(makePaymentCommand));
    }
}