Question

我正在尝试从其他API获取一些数据，我需要从JSON对象获取StatusCode，但是我正在获取null对象。

我试图用StatusCode变量创建新类，但是我得到了null。我正在尝试获取此数据：

Data(data=[{"Number":"20450143160505","DateCreated":"11-06-2019 10:14:27","DocumentWeight":0.5,"CheckWeight":0,"SumBeforeCheckWeight":0,"PayerType":"Recipient","RecipientFullName":"","RecipientDateTime":"","ScheduledDeliveryDate":"12-06-2019","PaymentMethod":"Cash","CargoDescriptionString":"","CargoType":"Parcel","CitySender":"Сокільники","CityRecipient":"Київ","WarehouseRecipient":"Відділення №150 (до 30 кг): вул. Антоновича, 43 (м.\"Олімпійська\")","CounterpartyType":"PrivatePerson","Redelivery":1,"RedeliverySum":"","RedeliveryNum":"","RedeliveryPayer":"","AfterpaymentOnGoodsCost":"","ServiceType":"WarehouseWarehouse","UndeliveryReasonsSubtypeDescription":"","WarehouseRecipientNumber":150,"LastCreatedOnTheBasisNumber":"","LastCreatedOnTheBasisDocumentType":"","LastCreatedOnTheBasisPayerType":"","LastCreatedOnTheBasisDateTime":"","LastTransactionStatusGM":"","LastTransactionDateTimeGM":"","WarehouseRecipientInternetAddressRef":"916c7c93-8460-11e4-acce-0050568002cf","MarketplacePartnerToken":"","DateScan":"12:23 12.06.2019","ClientBarcode":"","SenderAddress":"","RecipientAddress":"","CounterpartySenderDescription":"","CounterpartyRecipientDescription":"","CounterpartySenderType":"Organization","PaymentStatus":"","PaymentStatusDate":"","AmountToPay":"","AmountPaid":"","WarehouseRecipientRef":"916c7c94-8460-11e4-acce-0050568002cf","DocumentCost":40,"AnnouncedPrice":"","OwnerDocumentNumber":"","DateFirstDayStorage":"2019-06-21","InternationalDeliveryType":"","DaysStorageCargo":"","RecipientWarehouseTypeRef":"841339c7-591a-42e2-8233-7a0a00f0ed6f","StorageAmount":"","StoragePrice":"","VolumeWeight":"0.50","SeatsAmount":"1","OwnerDocumentType":"","ActualDeliveryDate":"2019-06-12 12:23:22","DateReturnCargo":"","CardMaskedNumber":"","Status":"Прибув у відділення","StatusCode":"7","RefEW":"8ed817ef-8c18-11e9-91ff-0025b501a04b","RedeliveryPaymentCardRef":"","RedeliveryPaymentCardDescription":"","CreatedOnTheBasis":"","DatePayedKeeping":"2019-06-21 00:00:00","OnlineCreditStatusCode":"","OnlineCreditStatus":""}])

获取数据的方法：

RestTemplate restTemplate = new RestTemplate();
                Data string = restTemplate.postForObject(blalba,blabla,Data.class)

我的班级

public class Data {
    @JsonProperty("data")
    private JsonNode data;
//get set
}

Answer 1

有几种方法可以实现它：

使用#include <string> #include <system_error> // NOTE: if we rename this from 'enums' to 'app' (comment below) and do // the needed name change changes in the code it will compile just fine //namespace app namespace enums { // error type enum enum class Error { SignalFail, // failed to set up or execute signal BadArgument, // bad argument passed to function InvalidPointer, // Pointer is invalid NoImplementation, // No implementation OutOfRange, // Out of range AlocationFailed, // Failed to alocate memory MemoryReadFailed, // Failed to read memory Unexpected // Unexpected execution flow }; // error condition enum enum class Condition { code_error, unknown_error }; } // Register Error and Condition as error enum and condition enum namespace std { template<> struct is_error_code_enum<enums::Error> : public true_type {}; template<> struct is_error_condition_enum<enums::Condition> : public true_type {}; } namespace app { // Category types are used to identify the source of an error. // They also define the relation between error_code and error_condition objects of its category, // as well as the message set for error_code objects. class error_category_t : public std::error_category { public: error_category_t() noexcept {}; inline const char* name() const noexcept override; std::error_condition default_error_condition(int err_value) const noexcept override; inline bool equivalent(const std::error_code& err_code, int err_value) const noexcept override; inline bool equivalent(int err_value, const std::error_condition& err_cond) const noexcept override; std::string message(int ev) const override; private: error_category_t(const error_category_t&) = delete; error_category_t(error_category_t&&) = delete; error_category_t& operator=(const error_category_t&) = delete; error_category_t& operator=(error_category_t&&) = delete; } const error_category; const char* error_category_t::name() const noexcept { return "app category"; } bool error_category_t::equivalent(const std::error_code& err_code, int err_value) const noexcept { return *this == err_code.category() && static_cast<int>(default_error_condition(err_code.value()).value()) == err_value; } bool error_category_t::equivalent(int err_value, const std::error_condition& err_cond) const noexcept { return default_error_condition(err_value) == err_cond; } // // make_error_condition overload to generate custom conditions: // This function is called by error_condition's constructor for error condition enum types, // and should be overloaded for all custom error condition enum types in order to // provide a mechanism to generate the appropriate error_condition objects from them. // inline std::error_condition make_error_condition(enums::Condition ec) noexcept { return std::error_condition(static_cast<int>(ec), error_category); } // // This function is called by error_code's constructor for error code enum types // inline std::error_code make_error_code(enums::Error code) noexcept { return std::error_code(static_cast<int>(code), error_category); } } namespace app { std::error_condition error_category_t::default_error_condition(int err_value) const noexcept { switch (static_cast<enums::Error>(err_value)) { case enums::Error::SignalFail: case enums::Error::BadArgument: case enums::Error::InvalidPointer: case enums::Error::NoImplementation: case enums::Error::OutOfRange: case enums::Error::AlocationFailed: case enums::Error::MemoryReadFailed: case enums::Error::Unexpected: return std::error_condition(enums::Condition::code_error); default: return std::error_condition(enums::Condition::unknown_error); } } std::string error_category_t::message(int err_value) const { switch (static_cast<enums::Error>(err_value)) { case enums::Error::SignalFail: return "Signaling failed"; case enums::Error::BadArgument: return "Bad Argument"; case enums::Error::InvalidPointer: return "Invalid pointer"; case enums::Error::NoImplementation: return "No implementation"; case enums::Error::OutOfRange: return "Out of range"; case enums::Error::AlocationFailed: return "Memory allocation failed"; case enums::Error::MemoryReadFailed: return "Memory read failed"; case enums::Error::Unexpected: return "Unexpected execution flow"; default: return "Unknown error"; } } }

您可以将响应有效载荷读取为Map<String, Object>：

Map<String, Object>

仅映射您需要的属性

定义一个映射所需属性的类：

ParameterizedTypeReference<HashMap<String, Object>> responseType = 
        new ParameterizedTypeReference<HashMap<String, Object>>() {};

Map<String, Object> responsePayload = 
        restTemplate.exchange(purchaseRequestDetailsEndpoint, HttpMethod.POST,
                new HttpEntity<>(requestPayload), responseType);

String statusCode = responsePayload.get("StatusCode");

并使用上面定义的类读取响应有效负载：

@Data
@JsonIgnoreProperties(ignoreUnknown = true)
public class ResponsePayload {

    @JsonProperty("StatusCode")
    private String statusCode;
}

或者，您可以映射所需的属性，并将其余属性存储在映射中：

ResponsePayload responsePayload = 
        restTemplate.postForObject(uri, request, ResponsePayload.class);

String statusCode = responsePayload.getStatusCode();

如何从JSON对象获取特定变量？

1 个答案:

仅映射您需要的属性