Spring Boot 项目五维度九层次分层架构实现实践研究——持续更新中

var code = “12433d02-b242-4fd2-937d-750761a365ea”

说明:本博文有参考一些技术博主的思路,据实践内容及代码持续总结更新中。

五个分层维度:SpringBoot工程分层实战

1 分层思想

计算机领域有一句话:计算机中任何问题都可通过增加一个虚拟层解决。这句体现了分层思想重要性,分层思想同样适用于Java工程架构。

分层优点是每层只专注本层工作,可以类比设计模式单一职责原则,或者经济学比较优势原理,每层只做本层最擅长的事情。

分层缺点是层之间通信时,需要通过适配器,翻译成本层或者下层可以理解的信息,通信成本有所增加。

我认为工程分层需要从五个维度思考:

(1) 单一

每层只处理一类事情,满足单一职责原则

(2) 降噪

信息在每一层进行传输,满足最小知识原则,只向下层传输必要信息

(3) 适配

每层都需要一个适配器,翻译信息为本层或者下层可以理解的信息

(4) 业务

业务对象可以整合业务逻辑,例如使用充血模型整合业务

(5) 数据

数据对象尽量纯净,尽量不要聚合业务

1.2 九层结构

综上所述SpringBoot工程可以分为九层:

  • 工具层:util
  • 整合层:integration
  • 基础层:infrastructure
  • 服务层:service
  • 领域层:domain
  • 门面层:facade
  • 控制层:controller
  • 客户端:client
  • 启动层:boot

2 分层详解

创建测试项目user-demo-service:

user-demo-service
-user-demo-service-boot
-user-demo-service-client
-user-demo-service-controller
-user-demo-service-domain
-user-demo-service-facade
-user-demo-service-infrastructure
-user-demo-service-integration
-user-demo-service-service
-user-demo-service-util

2.1 util
工具层承载工具代码

不依赖本项目其它模块

只依赖一些通用工具包

user-demo-service-util
-/src/main/java
-date
-DateUtil.java
-json
-JSONUtil.java
-validate
-BizValidator.java

2.2 infrastructure
基础层核心是承载数据访问,entity实体对象承载在本层。

2.2.1 项目结构
代码层分为两个领域:

player:运动员
game:比赛
每个领域具有两个子包:

entity
mapper
user-demo-service-infrastructure
-/src/main/java
-player
-entity
-PlayerEntity.java
-mapper
-PlayerEntityMapper.java
-game
-entity
-GameEntity.java
-mapper
-GameEntityMapper.java
-/src/main/resources
-mybatis
-sqlmappers
-gameEntityMappler.xml
-playerEntityMapper.xml

复制代码

2.2.2 本项目间依赖关系

infrastructure只依赖工具模块

<dependency>
    <groupId>com.test.javafront</groupId>
    <artifactId>user-demo-service-util</artifactId>
</dependency>

2.2.3 核心代码

创建运动员数据表:

CREATE TABLE `player` (
    `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键',
    `player_id` varchar(256) NOT NULL COMMENT '运动员编号',
    `player_name` varchar(256) NOT NULL COMMENT '运动员名称',
    `height` int(11) NOT NULL COMMENT '身高',
    `weight` int(11) NOT NULL COMMENT '体重',
    `game_performance` text COMMENT '最近一场比赛表现',
    `creator` varchar(256) NOT NULL COMMENT '创建人',
    `updator` varchar(256) NOT NULL COMMENT '修改人',
    `create_time` datetime NOT NULL COMMENT '创建时间',
    `update_time` datetime NOT NULL COMMENT '修改时间',
    PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8

运动员实体对象,gamePerformance字段作为string保存在数据库,这体现了数据层尽量纯净,不要整合过多业务,解析任务应该放在业务层:

public class PlayerEntity {
    private Long id;
    private String playerId;
    private String playerName;
    private Integer height;
    private Integer weight;
    private String creator;
    private String updator;
    private Date createTime;
    private Date updateTime;
    private String gamePerformance;
}

运动员Mapper对象:

@Repository
public interface PlayerEntityMapper {
    int insert(PlayerEntity record);
    int updateById(PlayerEntity record);
    PlayerEntity selectById(@Param("playerId") String playerId);
}

2.3 domain

2.3.1 概念说明

领域层是DDD流行兴起之概念

可以通过三组对比理解领域层

领域对象 VS 数据对象
领域对象 VS 业务对象
领域层 VS 业务层

(1) 领域对象 VS 数据对象

数据对象字段尽量纯净,使用基本类型

public class PlayerEntity {
    private Long id;
    private String playerId;
    private String playerName;
    private Integer height;
    private Integer weight;
    private String creator;
    private String updator;
    private Date createTime;
    private Date updateTime;
    private String gamePerformance;
}

以查询结果领域对象为例

领域对象需要体现业务含义

public class PlayerQueryResultDomain {
    private String playerId;
    private String playerName;
    private Integer height;
    private Integer weight;
    private GamePerformanceVO gamePerformance;
}

public class GamePerformanceVO {
    // 跑动距离
    private Double runDistance;
    // 传球成功率
    private Double passSuccess;
    // 进球数
    private Integer scoreNum;
}

(2) 领域对象 VS 业务对象

业务对象同样会体现业务,领域对象和业务对象有什么不同呢?其中一个最大不同是领域对象采用充血模型聚合业务。

运动员新增业务对象:

public class PlayerCreateBO {
    private String playerName;
    private Integer height;
    private Integer weight;
    private GamePerformanceVO gamePerformance;
    private MaintainCreateVO maintainInfo;
}

运动员新增领域对象:

public class PlayerCreateDomain implements BizValidator {
private String playerName;
private Integer height;
private Integer weight;
private GamePerformanceVO gamePerformance;
private MaintainCreateVO maintainInfo;

    @Override
    public void validate() {
        if (StringUtils.isEmpty(playerName)) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (null == height) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (height > 300) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (null == weight) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (null != gamePerformance) {
            gamePerformance.validate();
        }
        if (null == maintainInfo) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        maintainInfo.validate();
    }
}

(3) 领域层 VS 业务层

领域层和业务层都包含业务,二者不是替代关系,而是互补关系。业务层可以更加灵活组合不同领域业务,并且可以增加流控、监控、日志、权限,分布式锁等控制,相较于领域层功能更为丰富。

2.3.2 项目结构

代码层分为两个领域:

player:运动员
game:比赛

每个领域具有三个子包:

domain:领域对象
event:领域事件
vo:值对象
user-demo-service-domain
-/src/main/java
-base
-domain
-BaseDomain.java
-event
-BaseEvent.java
-vo
-BaseVO.java
-MaintainCreateVO.java
-MaintainUpdateVO.java
-player
-domain
-PlayerCreateDomain.java
-PlayerUpdateDomain.java
-PlayerQueryResultDomain.java
-event
-PlayerUpdateEvent.java
-vo
-GamePerformanceVO.java
-game
-domain
-GameCreateDomain.java
-GameUpdateDomain.java
-GameQueryResultDomain.java
-event
-GameUpdateEvent.java
-vo
-GameSubstitutionVO.java

2.3.3 本项目间依赖关系
domain依赖本项目两个模块:

util
client

之所以依赖client模块是因为领域对象聚合了业务校验,以下信息需要暴露至外部:

BizException
ErrorCodeBizEnum
<dependency>
<groupId>com.test.javafront</groupId>
<artifactId>user-demo-service-util</artifactId>
</dependency>
<dependency>
<groupId>com.test.javafront</groupId>
<artifactId>user-demo-service-client</artifactId>
</dependency>

2.3.4 核心代码

以运动员修改领域对象为例:

// 运动员修改领域对象

public class PlayerUpdateDomain extends BaseDomain implements BizValidator {
private String playerId;
private String playerName;
private Integer height;
private Integer weight;
private String updator;
private Date updatetime;
private GamePerformanceVO gamePerformance;
private MaintainUpdateVO maintainInfo;

    @Override
    public void validate() {
        if (StringUtils.isEmpty(playerId)) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (StringUtils.isEmpty(playerName)) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (null == height) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (height > 300) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (null == weight) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (null != gamePerformance) {
            gamePerformance.validate();
        }
        if (null == maintainInfo) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        maintainInfo.validate();
    }
}

// 比赛表现值对象

public class GamePerformanceVO implements BizValidator {

    // 跑动距离
    private Double runDistance;
    // 传球成功率
    private Double passSuccess;
    // 进球数
    private Integer scoreNum;
 
    @Override
    public void validate() {
        if (null == runDistance) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (null == passSuccess) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (Double.compare(passSuccess, 100) > 0) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (null == runDistance) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (null == scoreNum) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
    }
}

// 修改人值对象

public class MaintainUpdateVO implements BizValidator {

    // 修改人
    private String updator;
    // 修改时间
    private Date updateTime;
 
    @Override
    public void validate() {
        if (null == updator) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
        if (null == updateTime) {
            throw new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT);
        }
    }
}

2.4 service

2.4.1 项目结构

user-demo-service-service
-/src/main/java
-player
-adapter
-PlayerServiceAdapter.java
-event
-PlayerMessageSender.java
-service
-PlayerService.java
-game
-adapter
-GameServiceAdapter.java
-event
-GameMessageSender.java
-service
-GameService.java

2.4.2 本项目间依赖关系
service依赖本项目四个模块:

util
domain
integration
infrastructure
<dependency>
<groupId>com.test.javafront</groupId>
<artifactId>user-demo-service-domain</artifactId>
</dependency>
<dependency>
<groupId>com.test.javafront</groupId>
<artifactId>user-demo-service-infrastructure</artifactId>
</dependency>
<dependency>
<groupId>com.test.javafront</groupId>
<artifactId>user-demo-service-util</artifactId>
</dependency>
<dependency>
<groupId>com.test.javafront</groupId>
<artifactId>user-demo-service-integration</artifactId>
</dependency>

2.4.3 核心代码

以运动员编辑服务为例:

// 运动员服务

public class PlayerService {

    @Resource
    private PlayerEntityMapper playerEntityMapper;
    @Resource
    private PlayerMessageSender playerMessageSender;
    @Resource
    private PlayerServiceAdapter playerServiceAdapter;
 
    public boolean updatePlayer(PlayerUpdateDomain player) {
        AssertUtil.notNull(player, new BizException(ErrorCodeBizEnum.ILLEGAL_ARGUMENT));
        player.validate();
        PlayerEntity entity = playerServiceAdapter.convertUpdate(player);
        playerEntityMapper.updateById(entity);
        playerMessageSender.sendPlayerUpdatemessage(player);
        return true;
    }
}

// 运动员消息服务

public class PlayerMessageSender {

    @Resource
    private PlayerServiceAdapter playerServiceAdapter;
 
    public boolean sendPlayerUpdatemessage(PlayerUpdateDomain domain) {
        PlayerUpdateEvent event = playerServiceAdapter.convertUpdateEvent(domain);
        log.info("sendPlayerUpdatemessage event={}", event);
        return true;
    }
}

// 服务适配器

public class PlayerServiceAdapter {

    // domain -> entity
    public PlayerEntity convertUpdate(PlayerUpdateDomain domain) {
        PlayerEntity player = new PlayerEntity();
        player.setPlayerId(domain.getPlayerId());
        player.setPlayerName(domain.getPlayerName());
        player.setWeight(domain.getWeight());
        player.setHeight(domain.getHeight());
        if (null != domain.getGamePerformance()) {
            player.setGamePerformance(JacksonUtil.bean2Json(domain.getGamePerformance()));
        }
        String updator = domain.getMaintainInfo().getUpdator();
        Date updateTime = domain.getMaintainInfo().getUpdateTime();
        player.setUpdator(updator);
        player.setUpdateTime(updateTime);
        return player;
    }
 
    // domain -> event
    public PlayerUpdateEvent convertUpdateEvent(PlayerUpdateDomain domain) {
        PlayerUpdateEvent event = new PlayerUpdateEvent();
        event.setPlayerUpdateDomain(domain);
        event.setMessageId(UUID.randomUUID().toString());
        event.setMessageId(PlayerMessageType.UPDATE.getMsg());
        return event;
    }
}

2.5 intergration
本项目可能会依赖外部服务,那么将外部DTO转换为本项目可以理解的对象,需要在本层处理。

2.5.1 项目结构
假设本项目调用了用户中心服务:

user-demo-service-intergration
-/src/main/java
-user
-adapter
-UserClientAdapter.java
-proxy
-UserClientProxy.java

复制代码
2.5.2 本项目间依赖关系
intergration依赖本项目两个模块:

util
domain

之所以依赖domain模块,是因为本层需要将外部DTO转换为本项目可以理解的对象,这些对象就放在domain模块。

<dependency>
    <groupId>com.test.javafront</groupId>
    <artifactId>user-demo-service-domain</artifactId>
</dependency>
<dependency>
    <groupId>com.test.javafront</groupId>
    <artifactId>user-demo-service-util</artifactId>
</dependency>

2.5.3 核心代码
现在我们将外部对象UserClientDTO

转换为本项目领域对象UserInfoDomain

(1) 外部服务

// 外部对象

public class UserInfoClientDTO implements Serializable {
private String id;
private String name;
private Date createTime;
private Date updateTime;
private String mobile;
private String cityCode;
private String addressDetail;
}

// 外部服务

public class UserClientService {

    // RPC模拟
    public UserInfoClientDTO getUserInfo(String userId) {
        UserInfoClientDTO userInfo = new UserInfoClientDTO();
        userInfo.setId(userId);
        userInfo.setName(userId);
        userInfo.setCreateTime(DateUtil.now());
        userInfo.setUpdateTime(DateUtil.now());
        userInfo.setMobile("test-mobile");
        userInfo.setCityCode("test-city-code");
        userInfo.setAddressDetail("test-address-detail");
        return userInfo;
    }
}

(2) 本项目领域对象

domain模块新增user领域:

user-demo-service-domain
-/src/main/java
-user
-domain
-UserDomain.java
-vo
-UserAddressVO.java
-UserContactVO.java

user领域对象代码:

// 用户领域

public class UserInfoDomain extends BaseDomain {
    private UserContactVO contactInfo;
    private UserAddressVO addressInfo;
}

// 地址值对象

public class UserAddressVO extends BaseVO {
    private String cityCode;
    private String addressDetail;
}

// 联系方式值对象

public class UserContactVO extends BaseVO {
private String mobile;
}

(3) 适配器

public class UserClientAdapter {

    // third dto -> domain
    public UserInfoDomain convertUserDomain(UserInfoClientDTO userInfo) {
        UserInfoDomain userDomain = new UserInfoDomain();
        UserContactVO contactVO = new UserContactVO();
        contactVO.setMobile(userInfo.getMobile());
        userDomain.setContactInfo(contactVO);
 
        UserAddressVO addressVO = new UserAddressVO();
        addressVO.setCityCode(userInfo.getCityCode());
        addressVO.setAddressDetail(userInfo.getAddressDetail());
        userDomain.setAddressInfo(addressVO);
        return userDomain;
    }
}

(4) 调用外部服务

public class UserClientProxy {

    @Resource
    private UserClientService userClientService;
    @Resource
    private UserClientAdapter userClientAdapter;
 
    public UserInfoDomain getUserInfo(String userId) {
        UserInfoClientDTO user = userClientService.getUserInfo(userId);
        UserInfoDomain result = userClientAdapter.convertUserDomain(user);
        return result;
    }
}

2.6 facade + client

设计模式中有一种Facade模式,称为门面模式或者外观模式。这种模式提供一个简洁对外语义,屏蔽内部系统复杂性。

client承载数据对外传输对象DTO,facade承载对外服务,这两层必须满足最小知识原则,无关信息不必对外透出。

这样做有两个优点:

简洁性:对外服务语义明确简洁
安全性:敏感字段不能对外透出

2.6.1 项目结构

(1) client

user-demo-service-client
-/src/main/java
-base
-dto
-BaseDTO.java
-error
-BizException.java
-BizErrorCode.java
-event
-BaseEventDTO.java
-result
-ResultDTO.java
-player
-dto
-PlayerCreateDTO.java
-PlayerQueryResultDTO.java
-PlayerUpdateDTO.java
-enums
-PlayerMessageTypeEnum.java
-event
-PlayerUpdateEventDTO.java
-service
-PlayerClientService.java

(2) facade

user-demo-service-facade
-/src/main/java
-player
-adapter
-PlayerFacadeAdapter.java
-impl
-PlayerClientServiceImpl.java
-game
-adapter
-GameFacadeAdapter.java
-impl
-GameClientServiceImpl.java

2.6.2 本项目间依赖关系
client不依赖本项目其它模块,这一点非常重要,因为client会被外部引用,必须保证这一层简洁和安全。

facade依赖本项目三个模块:

domain
client
service
<dependency>
    <groupId>com.test.javafront</groupId>
    <artifactId>user-demo-service-domain</artifactId>
</dependency>
    <dependency>
    <groupId>com.test.javafront</groupId>
    <artifactId>user-demo-service-client</artifactId>
</dependency>
<dependency>
    <groupId>com.test.javafront</groupId>
    <artifactId>user-demo-service-service</artifactId>
</dependency>

2.6.3 核心代码

(1) DTO

以查询运动员信息为例,查询结果DTO只封装最关键字段,例如运动员ID、创建时间、修改时间等业务不强字段就无须透出:

public class PlayerQueryResultDTO implements Serializable {
    private String playerName;
    private Integer height;
    private Integer weight;
    private GamePerformanceDTO gamePerformanceDTO;
}

(2) 客户端服务

public interface PlayerClientService {
    public ResultDTO<PlayerQueryResultDTO> queryById(String playerId);
}

(3) 适配器

public class PlayerFacadeAdapter {

    // domain -> dto
    public PlayerQueryResultDTO convertQuery(PlayerQueryResultDomain domain) {
        if (null == domain) {
            return null;
        }
        PlayerQueryResultDTO result = new PlayerQueryResultDTO();
        result.setPlayerId(domain.getPlayerId());
        result.setPlayerName(domain.getPlayerName());
        result.setHeight(domain.getHeight());
        result.setWeight(domain.getWeight());
        if (null != domain.getGamePerformance()) {
            GamePerformanceDTO performance = convertGamePerformance(domain.getGamePerformance());
            result.setGamePerformanceDTO(performance);
        }
        return result;
    }
}        

(4) 服务实现

public class PlayerClientServiceImpl implements PlayerClientService {

    @Resource
    private PlayerService playerService;
    @Resource
    private PlayerFacadeAdapter playerFacadeAdapter;
 
    @Override
    public ResultDTO<PlayerQueryResultDTO> queryById(String playerId) {
        PlayerQueryResultDomain resultDomain = playerService.queryPlayerById(playerId);
        if (null == resultDomain) {
            return ResultCommonDTO.success();
        }
        PlayerQueryResultDTO result = playerFacadeAdapter.convertQuery(resultDomain);
        return ResultCommonDTO.success(result);
    }
}

2.7 controller

facade服务实现可以作为RPC提供服务,controller则作为本项目HTTP接口提供服务,供前端调用。

controller需要注意HTTP相关特性,敏感信息例如登陆用户ID不能依赖前端传递,登陆后前端会在请求头带一个登陆用户信息,服务端需要从请求头中获取并解析。

2.7.1 项目结构

user-demo-service-controller
-/src/main/java
-config
-CharsetConfig.java
-controller
-player
-PlayerController.java
-game
-GameController.java

2.7.2 本项目依赖关系

controller依赖本项目一个模块:

facade

根据依赖传递原理同时依赖以下模块:

domain
client
service
<dependency>
    <groupId>com.test.javafront</groupId>
    <artifactId>user-demo-service-facade</artifactId>
</dependency>

2.7.3 核心代码

@RestController
@RequestMapping("/player")
public class PlayerController {

    @Resource
    private PlayerClientService playerClientService;
 
    @PostMapping("/add")
    public ResultDTO<Boolean> add(@RequestHeader("test-login-info") String loginUserId, @RequestBody PlayerCreateDTO dto) {
        dto.setCreator(loginUserId);
        ResultCommonDTO<Boolean> resultDTO = playerClientService.addPlayer(dto);
        return resultDTO;
    }
 
    @PostMapping("/update")
    public ResultDTO<Boolean> update(@RequestHeader("test-login-info") String loginUserId, @RequestBody PlayerUpdateDTO dto) {
        dto.setUpdator(loginUserId);
        ResultCommonDTO<Boolean> resultDTO = playerClientService.updatePlayer(dto);
        return resultDTO;
    }
 
    @GetMapping("/{playerId}/query")
    public ResultDTO<PlayerQueryResultDTO> queryById(@RequestHeader("test-login-info") String loginUserId, @PathVariable("playerId") String playerId) {
        ResultCommonDTO<PlayerQueryResultDTO> resultDTO = playerClientService.queryById(playerId);
        return resultDTO;
    }
}

2.8 boot

boot作为启动层,只有启动入口代码

2.8.1 项目结构

所有模块代码均必须属于com.user.demo.service子路径

user-demo-service-boot
-/src/main/java
-com.user.demo.service
-MainApplication.java

2.8.2 本项目间依赖
boot引用本项目所有模块

util
integration
infrastructure
service
domain
facade
controller
client

2.8.3 核心代码

@MapperScan("com.user.demo.service.infrastructure.*.mapper")
@SpringBootApplication
public class MainApplication {
    public static void main(final String[] args) {
        SpringApplication.run(MainApplication.class, args);
    }
}

3 文章总结

我们再次回顾分层五个思考维度:

(1) 单一

每层只处理一类事情,例如util只承载工具对象,integration只处理外部服务,每层职责单一且清晰

(2) 降噪

如无必要无增实体,例如查询结果DTO只透出最关键字段,例如运动员ID、创建时间、修改时间等业务不强字段无须透出

(3) 适配

service、facade、intergration层都存在适配器,翻译信息为本层或者下层可以理解的信息

(4) 业务

业务对象可以通过充血模型聚合业务,例如在业务对象中聚合业务校验逻辑

(5) 数据

数据对象要纯净,例如通过string类型保存比赛表现,数据层无需解析

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转载自blog.csdn.net/lqzixi/article/details/132114466