润色一下

<properties>
    <p6spy.version>3.9.0</p6spy.version>
</properties>
<dependency>
    <groupId>p6spy</groupId>
    <artifactId>p6spy</artifactId>
    <version>${p6spy.version}</version>
</dependency>

src/main/resources下新建spy.properties配置文件：

driverlist=com.mysql.cj.jdbc.Driver
logfile=spy.log
dateformat=yyyy-MM-dd HH:mm:ss.SS
logMessageFormat=com.p6spy.engine.spy.appender.CustomLineFormat
customLogMessageFormat=- %(currentTime) | took %(executionTime)ms | connection %(connectionId) 
EXPLAIN %(sql);

filter=true
exclude=select 1 from dual

application.properties修改成：

#spring.datasource.url=jdbc:mysql://localhost:3306/product_center? useSSL=false&serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=convertToNull&useUnicode=true&characterEncoding=UTF-8
spring.datasource.url=jdbc:p6spy:mysql://localhost:3306/product_center? useSSL=false&serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=convertToNull&useUnicode=true&characterEncoding=UTF-8
spring.datasource.username=<your username>
spring.datasource.password=<your password>
#spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.driver-class-name=com.p6spy.engine.spy.P6SpyDriver

增加全局异常处理

@ControllerAdvice
@ResponseBody
public class GlobalDefaultExceptionHandler {
    private static final String UNKNOWN_ERROR_CODE = "unknown-error";
    private static final String SYSTEM_ERROR_INFO = "系统异常，请联系管理员";
    private static final String ILLEGAL_PARAM_CODE = "illegal-param";

    @ExceptionHandler(value = IllegalArgumentException.class)
    public ApiResult illegalParamExceptionHandler(IllegalArgumentException e) throws Exception {
        // log todo
        return ApiResult.error(ILLEGAL_PARAM_CODE, e.getMessage());
    }

    @ExceptionHandler(value = BusinessException.class)
    public ApiResult businessExceptionHandler(BusinessException e) throws Exception {
        // log todo
        return ApiResult.error(e.getCode(), e.getMessage());
    }

    @ExceptionHandler(value = Exception.class)
    public ApiResult defaultErrorHandler(Exception e) throws Exception {
        // log todo
        e.printStackTrace();
        return ApiResult.error(UNKNOWN_ERROR_CODE, SYSTEM_ERROR_INFO);
    }
}

数据库添加自定义的审计字段

domain.common.model:

@MappedSuperclass
@Data
public abstract class AuditEntity implements Serializable {
    @Column(name = "is_delete", columnDefinition = "TINYINT(1) DEFAULT 0")
    protected Boolean isDelete;
    @Column(name = "created_by", length = 11, nullable = false)
    protected Integer createdBy;
    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "created_at", columnDefinition = "DATETIME NULL DEFAULT CURRENT_TIMESTAMP")
    protected Date createdAt;
    @Column(name = "updated_by", length = 11, nullable = false)
    protected Integer updatedBy;
    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "updated_at", columnDefinition = "DATETIME NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP")
    protected Date updatedAt;

    @PrePersist
    protected void onCreate() {
        updatedAt = createdAt = new Date();
        isDelete = false;
    }

    @PreUpdate
    protected void onUpdate() {
        updatedAt = new Date();
    }
}

public class Product extends AuditEntity implements Serializable {
      ...
}

确定需求->构建模型->实现模型->调整模型->实现模型...，走完这个过程，相信你对DDD的玩法已经有了一定的了解，而且我相信你大概能领略到DDD代码的优美之处。好的代码应该是高内聚低耦合的，DDD的代码就是要让高内聚低耦合落地。

高内聚体现在业务代码都集中在领域对象里了（聚合根，实体，值对象，域服务）。业务规则在代码里都有非常清楚的对应关系。代码真正体现了面向对象的思想。
低耦合体现在聚合根不直接引用其它聚合根。 低耦合还有一个很关键的点是领域事件。 这个跟DDD事件驱动的架构风格分不开。

说起DDD的架构风格，最常用的就是CQRS（读写分离）和事件驱动。
事件驱动又分 event storming和event sourcing（个人理解，不对请指正），event sourcing看起来比较极端，似乎应用场景针对性太强，也就是说比较少见。

如果你的业务很复杂，事件比较多，可以使用event storming。商品中心相对比较简单，用读写分离就差不多了。本人水平有限，本系列文章旨在抛砖引玉，希望大家能留言讨论。

demo下载地址： productcenter6.zip