利用 Lazy 构造通用 User 实体的工厂是如何实现的？

@Component public class UserFactory {

// 部门服务, rpc 接口 @Resource private DepartmentService departmentService;

// 主管服务, rpc 接口 @Resource private SupervisorService supervisorService;

// 权限服务, rpc 接口 @Resource private PermissionService permissionService;

public User buildUser(long uid) { Lazy< String> departmentLazy = Lazy.of(() -> departmentService.getDepartment(uid)); // 通过部门获得主管 // department -> supervisor Lazy< Long> supervisorLazy = departmentLazy.map( department -> SupervisorService.getSupervisor(department) ); // 通过部门和主管获得权限 // department, supervisor -> permission Lazy< Set< String>> permissionsLazy = departmentLazy.flatMap(department -> supervisorLazy.map( supervisor -> permissionService.getPermissions(department, supervisor) ) );

User user = new User(); user.setUid(uid); user.setDepartment(departmentLazy); user.setSupervisor(supervisorLazy); user.setPermissions(permissionsLazy); } }