Thingsboard源码分析（三）遥测数据获取

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获取遥测数据

TelemetryController

首先找到入口，比如获取最新遥测数据方法getLatestTelemetry，/DEVICE/deviceId/values/timeseries 在 TelemetryController 中：

@RestController
@TbCoreComponent
// TbUrlConstants.TELEMETRY_URL_PREFIX=="/api/plugins/telemetry"
@RequestMapping(TbUrlConstants.TELEMETRY_URL_PREFIX)
@Slf4j
public class TelemetryController extends BaseController {

    // 这个组件负责获取设备遥测数据
    @Autowired
    private TimeseriesService tsService;

    // 这个组件时为了验证当前用户是否有权限去执行当前操作
    @Autowired
    private AccessValidator accessValidator;

    @Value("${transport.json.max_string_value_length:0}")
    private int maxStringValueLength;

    private ExecutorService executor;
    
    @PreAuthorize("hasAnyAuthority('SYS_ADMIN', 'TENANT_ADMIN', 'CUSTOMER_USER')")
    @RequestMapping(value = "/{entityType}/{entityId}/values/timeseries", method = RequestMethod.GET)
    @ResponseBody
    public DeferredResult<ResponseEntity> getLatestTimeseries(
            @PathVariable("entityType") String entityType, @PathVariable("entityId") String entityIdStr,
            @RequestParam(name = "keys", required = false) String keysStr,
            @RequestParam(name = "useStrictDataTypes", required = false, defaultValue = "false") Boolean useStrictDataTypes) throws ThingsboardException {
        SecurityUser user = getCurrentUser();

        return accessValidator.validateEntityAndCallback(getCurrentUser(), Operation.READ_TELEMETRY, entityType, entityIdStr,
                (result, tenantId, entityId) -> getLatestTimeseriesValuesCallback(result, user, entityId, keysStr, useStrictDataTypes));
    }
    
    private void getLatestTimeseriesValuesCallback(@Nullable DeferredResult<ResponseEntity> result, SecurityUser user, EntityId entityId, String keys, Boolean useStrictDataTypes) {
        ListenableFuture<List<TsKvEntry>> future;
        if (StringUtils.isEmpty(keys)) {
            // 如果我们不传入键名列表，则返回所有遥测数据。
            future = tsService.findAllLatest(user.getTenantId(), entityId);
        } else {
            // 如果传入键名列表，则只查找相关的遥测数据。比如查经纬度要将longitude和latitude传入这个接口
            future = tsService.findLatest(user.getTenantId(), entityId, toKeysList(keys));
        }
        Futures.addCallback(future, getTsKvListCallback(result, useStrictDataTypes), MoreExecutors.directExecutor());
    }
    
}

AccessValidator

这个类主要是用于判断当前访问者是否有访问遥测数据的权限

validateEntityAndCallback 重载方法很多，一定要注意区分。这里使用的是第一个方法

@Component
public class AccessValidator {
    ........
    // 这是第一个 validateEntityAndCallback 方法，这一步加入了出错处理方法
    public DeferredResult<ResponseEntity> validateEntityAndCallback(SecurityUser currentUser, Operation operation, String entityType, String entityIdStr,
                                                                    ThreeConsumer<DeferredResult<ResponseEntity>, TenantId, EntityId> onSuccess) throws ThingsboardException {
        // 调用了第二个 validateEntityAndCallback 方法
        return validateEntityAndCallback(currentUser, operation, entityType, entityIdStr, onSuccess,
               // 加入出错处理方法                          
         	   (result, t) -> handleError(t, result, HttpStatus.INTERNAL_SERVER_ERROR));
    }
    
    // 这是第二个 validateEntityAndCallback 方法，这一步根据id和类型（DEVICE）产生EntityId，以便找到这个设备
    public DeferredResult<ResponseEntity> validateEntityAndCallback(SecurityUser currentUser, Operation operation, String entityType, String entityIdStr,
                                                                    ThreeConsumer<DeferredResult<ResponseEntity>, TenantId, EntityId> onSuccess,
                                                                    BiConsumer<DeferredResult<ResponseEntity>, Throwable> onFailure) throws ThingsboardException {
        // 调用第四个 validateEntityAndCallback 方法
        return validateEntityAndCallback(currentUser, operation,                                    
               // 根据类型（DEVICE）和id产生EntityId实例，以便查找设备                          
               EntityIdFactory.getByTypeAndId(entityType, entityIdStr),onSuccess, onFailure);
    }
	
    // 这是第三个 validateEntityAndCallback 方法，没有被调用
    public DeferredResult<ResponseEntity> validateEntityAndCallback(SecurityUser currentUser, Operation operation, EntityId entityId,
                                                                    ThreeConsumer<DeferredResult<ResponseEntity>, TenantId, EntityId> onSuccess) throws ThingsboardException {
        return validateEntityAndCallback(currentUser, operation, entityId, onSuccess, (result, t) -> handleError(t, result, HttpStatus.INTERNAL_SERVER_ERROR));
    }

    // 这是第四个 validateEntityAndCallback 方法
    public DeferredResult<ResponseEntity> validateEntityAndCallback(SecurityUser currentUser, Operation operation, EntityId entityId,
                                                                    ThreeConsumer<DeferredResult<ResponseEntity>, TenantId, EntityId> onSuccess,
                                                                    BiConsumer<DeferredResult<ResponseEntity>, Throwable> onFailure) throws ThingsboardException {

        final DeferredResult<ResponseEntity> response = new DeferredResult<>();
		// 调用validate方法，根据当前EntityType来确定使用哪个方法
        validate(currentUser, operation, entityId, new HttpValidationCallback(response,
                new FutureCallback<DeferredResult<ResponseEntity>>() {
                    @Override
                    public void onSuccess(@Nullable DeferredResult<ResponseEntity> result) {
                        try {
                            onSuccess.accept(response, currentUser.getTenantId(), entityId);
                        } catch (Exception e) {
                            onFailure(e);
                        }
                    }

                    @Override
                    public void onFailure(Throwable t) {
                        onFailure.accept(response, t);
                    }
                }));

        return response;
    }
    
    public void validate(SecurityUser currentUser, Operation operation, EntityId entityId, FutureCallback<ValidationResult> callback) {
        switch (entityId.getEntityType()) {
            case DEVICE:
                // EntityType=='DEVICE'，调用validateDevice方法，直接返回响应结果到http response
                validateDevice(currentUser, operation, entityId, callback);
                return;
            case DEVICE_PROFILE:
                validateDeviceProfile(currentUser, operation, entityId, callback);
                return;
            /*。。。。。。。。。。。。。。*/
            default:
                //TODO: add support of other entities
                throw new IllegalStateException("Not Implemented!");
        }
    }
    
    private void validateDevice(final SecurityUser currentUser, Operation operation, EntityId entityId, FutureCallback<ValidationResult> callback) {
        // 系统管理员没有查看设备遥测数据的权限
        if (currentUser.isSystemAdmin()) {
            callback.onSuccess(ValidationResult.accessDenied(SYSTEM_ADMINISTRATOR_IS_NOT_ALLOWED_TO_PERFORM_THIS_OPERATION));
        } else {
            // 根据TenantId和DeviceId来查找Device实例
            ListenableFuture<Device> deviceFuture = deviceService.findDeviceByIdAsync(currentUser.getTenantId(), new DeviceId(entityId.getId()));
            Futures.addCallback(deviceFuture, getCallback(callback, device -> {
                if (device == null) {
                    return ValidationResult.entityNotFound(DEVICE_WITH_REQUESTED_ID_NOT_FOUND);
                } else {
                    try {
                        // 查找权限列表判断当前用户有无读取设备遥测数据的权限。如果没有权限将直接报错，然后出错处理
                        accessControlService.checkPermission(currentUser, Resource.DEVICE, operation, entityId, device);
                    } catch (ThingsboardException e) {
                        return ValidationResult.accessDenied(e.getMessage());
                    }
                    return ValidationResult.ok(device);
                }
            }), executor);
        }
    }
    
    public interface ThreeConsumer<A, B, C> {
        void accept(A a, B b, C c);
    }
}

TimeseriesService

这个类用于查找最新遥测数据

@Service
@Slf4j
public class BaseTimeseriesService implements TimeseriesService {
    
    // 这个组件负责查找所有最新遥测数据
    @Autowired
    private TimeseriesLatestDao timeseriesLatestDao;
    
    @Override
    public ListenableFuture<List<TsKvEntry>> findLatest(TenantId tenantId, EntityId entityId, Collection<String> keys) {
        validate(entityId);
        List<ListenableFuture<TsKvEntry>> futures = Lists.newArrayListWithExpectedSize(keys.size());
        keys.forEach(key -> Validator.validateString(key, "Incorrect key " + key));
        keys.forEach(key -> futures.add(timeseriesLatestDao.findLatest(tenantId, entityId, key)));
        return Futures.allAsList(futures);
    }

    @Override
    public ListenableFuture<List<TsKvEntry>> findAllLatest(TenantId tenantId, EntityId entityId) {
        //校验当前deviceId是否合法
        validate(entityId);
        // 根据tenantId和deviceId返回结果
        return timeseriesLatestDao.findAllLatest(tenantId, entityId);
    }
}

TimeseriesLatestDao

时序查找遥测数据的Dao层接口

@Slf4j
@Component
@SqlTsLatestAnyDaopublic 
class SqlTimeseriesLatestDao extends BaseAbstractSqlTimeseriesDao implements TimeseriesLatestDao {    		@Autowired    
    private SearchTsKvLatestRepository searchTsKvLatestRepository;
    @Override    
    public ListenableFuture<List<TsKvEntry>> findAllLatest(TenantId tenantId, EntityId entityId) {
        return getFindAllLatestFuture(entityId);    
    }        
    protected ListenableFuture<List<TsKvEntry>> getFindAllLatestFuture(EntityId entityId) {        
        return Futures.immediateFuture(DaoUtil.convertDataList(Lists.newArrayList(
            searchTsKvLatestRepository.findAllByEntityId(entityId.getId()))));
    }
}

SearchTsKvLatestDao

时序键值查找遥测数据的接口，在这里可以找到sql语句

@SqlTsLatestAnyDao@Repositorypublic class SearchTsKvLatestRepository {
    public static final String FIND_ALL_BY_ENTITY_ID = "findAllByEntityId"; 
    public static final String FIND_ALL_BY_ENTITY_ID_QUERY = "SELECT ts_kv_latest.entity_id AS entityId, ts_kv_latest.key AS key, ts_kv_dictionary.key AS strKey, ts_kv_latest.str_v AS strValue," +            " ts_kv_latest.bool_v AS boolValue, ts_kv_latest.long_v AS longValue, ts_kv_latest.dbl_v AS doubleValue, ts_kv_latest.json_v AS jsonValue, ts_kv_latest.ts AS ts FROM ts_kv_latest " +            "INNER JOIN ts_kv_dictionary ON ts_kv_latest.key = ts_kv_dictionary.key_id WHERE ts_kv_latest.entity_id = cast(:id AS uuid)";    
    @PersistenceContext   
    private EntityManager entityManager;   
    public List<TsKvLatestEntity> findAllByEntityId(UUID entityId) { 
        return entityManager.createNamedQuery(FIND_ALL_BY_ENTITY_ID, 
               TsKvLatestEntity.class.setParameter("id",entityId).getResultList());    
    }
}

EntityManager

进行并发查找的类，里面有很多加锁、刷新数据、查找的方法

Futures

异步响应组件。

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Java教程

Thingsboard源码分析（三）遥测数据获取

获取遥测数据

TelemetryController

AccessValidator

TimeseriesService

TimeseriesLatestDao

SearchTsKvLatestDao

EntityManager

Futures

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