后端路线完整示例用户管理系统

系列：后端路线 · 完整示例
把 Part 1(MySQL) ~ Part 4(部署) 全部焊死在一个项目里。这是一个复制即可跑的最小用户管理系统：建表 → 实体 → Mapper → Service → Controller → 接口自测。读完你已具备独立交付一个后端模块的能力。

1. 功能清单

接口	方法	路径	说明
注册用户	POST	`/api/users`	新增
用户列表	GET	`/api/users`	分页查询
用户详情	GET	`/api/users/{id}`	按主键查
更新用户	PUT	`/api/users/{id}`	改资料
删除用户	DELETE	`/api/users/{id}`	逻辑/物理删除
按名查询	GET	`/api/users?username=xxx`	条件查询

2. 建表 SQL（Part 1 的加强版）

CREATE TABLE `user` (
  `id`          BIGINT        NOT NULL AUTO_INCREMENT COMMENT '主键',
  `username`    VARCHAR(64)   NOT NULL DEFAULT '' COMMENT '用户名',
  `age`         TINYINT       NOT NULL DEFAULT 0  COMMENT '年龄',
  `balance`     DECIMAL(10,2) NOT NULL DEFAULT 0.00 COMMENT '余额',
  `status`      TINYINT       NOT NULL DEFAULT 1  COMMENT '1正常 2禁用',
  `deleted`     TINYINT       NOT NULL DEFAULT 0  COMMENT '逻辑删除标记',
  `created_at`  DATETIME      NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
  `updated_at`  DATETIME      NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
  PRIMARY KEY (`id`),
  UNIQUE KEY `uk_username` (`username`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='用户表';

3. 项目关键文件

3.1 依赖（pom.xml 核心）

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-spring-boot3-starter</artifactId>
    <version>3.5.7</version>
  </dependency>
  <dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <scope>runtime</scope>
  </dependency>
</dependencies>

3.2 配置（application.yml）

server:
  port: 8080
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/demo_db?useUnicode=true&characterEncoding=utf8mb4&serverTimezone=Asia/Shanghai
    username: root
    password: your_password
mybatis-plus:
  global-config:
    db-config:
      logic-delete-field: deleted     # 逻辑删除字段
      logic-not-delete-value: 0
      logic-delete-value: 1

3.3 实体（Entity）

@TableName("user")
public class User {
    @TableId(type = IdType.AUTO)
    private Long id;
    private String username;
    private Integer age;
    private BigDecimal balance;
    private Integer status;
    private Integer deleted;
    private LocalDateTime createdAt;
    private LocalDateTime updatedAt;
    // getter / setter 省略
}

3.4 Mapper

1 2	@Mapper public interface UserMapper extends BaseMapper<User> {}

3.5 Service

@Service
public class UserService extends ServiceImpl<UserMapper, User> {

    public User register(String username, int age) {
        // 业务校验：用户名唯一（也可靠唯一索引兜底）
        if (this.lambdaQuery().eq(User::getUsername, username).count() > 0) {
            throw new RuntimeException("用户名已存在");
        }
        User u = new User();
        u.setUsername(username);
        u.setAge(age);
        u.setBalance(BigDecimal.ZERO);
        u.setStatus(1);
        this.save(u);
        return u;
    }

    public IPage<User> pageList(long current, long size) {
        return this.page(new Page<>(current, size));
    }
}

3.6 Controller（统一响应）

@RestController
@RequestMapping("/api/users")
public class UserController {

    @Autowired
    private UserService userService;

    /** 注册 */
    @PostMapping
    public Result<User> register(@RequestBody User dto) {
        return Result.ok(userService.register(dto.getUsername(), dto.getAge()));
    }

    /** 列表（分页） */
    @GetMapping
    public Result<IPage<User>> list(@RequestParam(defaultValue="1") long current,
                                     @RequestParam(defaultValue="10") long size) {
        return Result.ok(userService.pageList(current, size));
    }

    /** 详情 */
    @GetMapping("/{id}")
    public Result<User> detail(@PathVariable Long id) {
        return Result.ok(userService.getById(id));
    }

    /** 更新 */
    @PutMapping("/{id}")
    public Result<Boolean> update(@PathVariable Long id, @RequestBody User dto) {
        dto.setId(id);
        return Result.ok(userService.updateById(dto));
    }

    /** 删除（逻辑删除） */
    @DeleteMapping("/{id}")
    public Result<Boolean> delete(@PathVariable Long id) {
        return Result.ok(userService.removeById(id));
    }
}

3.7 统一响应包装（Result）

public class Result<T> {
    private int code;
    private String msg;
    private T data;
    public static <T> Result<T> ok(T data) {
        Result<T> r = new Result<>();
        r.code = 0; r.msg = "ok"; r.data = data;
        return r;
    }
    // getter / setter 省略
}

4. 端到端自测（curl）

# 1. 注册
curl -X POST http://localhost:8080/api/users \
  -H "Content-Type: application/json" \
  -d '{"username":"zhang","age":20}'
# → {"code":0,"msg":"ok","data":{"id":1,"username":"zhang","age":20,...}}

# 2. 列表
curl "http://localhost:8080/api/users?current=1&size=10"

# 3. 详情
curl http://localhost:8080/api/users/1

# 4. 更新
curl -X PUT http://localhost:8080/api/users/1 \
  -H "Content-Type: application/json" \
  -d '{"age":21}'

# 5. 删除（触发逻辑删除，deleted 置 1）
curl -X DELETE http://localhost:8080/api/users/1

5. 这条链路的”全栈印证”

1
2
3

curl ──HTTP──► Controller(路由/参数) ──► Service(业务/校验)
                                      ──► Mapper(CRUD)
                                      ──► MySQL(持久化, Part1)