如何发出Post请求（从外部api获取JSON格式的数据）？

Question

如何使用POST方法将数据检索到数据库中，我创建了一个从外部服务api检索数据的方法-可以显示该方法，但我在创建将检索到的数据发送到数据库的适当方法时遇到了问题。

方法getCurrencyType从外部api检索数据：

@Component
public class CurrencyClient {

    public static final String URL_API_NBP = "http://api.nbp.pl/api/";
    private final RestTemplate restTemplate = new RestTemplate();

    public CurrencyModelDto getCurrencyType(String value) {
        CurrencyDto currencyDto = callGetMethod("exchangerates/rates/a/{currency}/", CurrencyDto.class, value);
        return CurrencyModelDto.builder()
                .code(currencyDto.getCode())
                .mid(currencyDto.getRates().stream().findFirst().get().getMid())
                .effectiveDate(currencyDto.getRates().stream().findFirst().get().getEffectiveDate())
                .build();
    }

    private <T> T callGetMethod(String url, Class<T> responseType, Object... objects) {
        return restTemplate.getForObject(URL_API_NBP + url,
                responseType, objects);
    }   
}

我准备了一个存储库和一个实体来创建一个数据库（创建了数据库，但没有填充数据）

@NoArgsConstructor
@Entity
@Getter
@Setter
public class Currency {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String code;
    private float mid;
    @DateTimeFormat(pattern = "yyyy-MM-dd")
    private LocalDate effectiveDate;
}

我目前创建了一个POST方法addMONcy，但它不允许检索和保存数据（逻辑不好？）。

public class CurrencyController {

    private final CurrencyService currencyService

    @PostMapping
    public void addCurrency(@RequestBody CurrencyModelDto currencyModel) {
        Currency currency = new Currency();
        currency.setCode(currencyModel.getCode());
        currency.setMid(currencyModel.getMid());
        currency.setEffectiveDate(currencyModel.getEffectiveDate());
        currencyService.save(currency);
    }

}

DTO型号：

@Getter
@Builder
public class CurrencyModelDto {
    private String code;
    private float mid;
    @DateTimeFormat(pattern = "yyyy-MM-dd")
    private LocalDate effectiveDate;
}

允许您保存数据的服务。

@Service
@Slf4j
@RequiredArgsConstructor
public class CurrencyService {

    private final CurrencyRepository currencyRepository;

    public void save(Currency currency) {
        currencyRepository.save(currency);
    }
}

因此，我有一个问题，就是如何正确地创建一个POST方法，该方法将与getCurrencyType方法“交互”，并允许我保存从getCurrencyType方法检索的数据

Answer 1

你的控制器应该是这样的

import java.util.Objects;

@RestController
public class CurrencyController {

    private final CurrencyService currencyService;
    private final CurrencyClient currencyClient;

    public CurrencyController(CurrencyService currencyService, CurrencyClient currencyClient) {
        this.currencyService = currencyService;
        this.currencyClient = currencyClient;
    }

    @PostMapping(("/addCurrency/{value}"))
    public void addCurrency(@PathVariable String value) {
        CurrencyModelDto currencyModelDto = currencyClient.getCurrencyType(value);
        if (Objects.nonNull(currencyClient)) {
            Currency currency = new Currency();
            currency.setCode(currencyModelDto.getCode());
            currency.setMid(currencyModelDto.getMid());
            currency.setEffectiveDate(currencyModelDto.getEffectiveDate());
            currencyService.save(currency);
        }

    }

}

然后，如果您使用的是maven工具，请运行应用程序

$ mvn spring-boot:run

然后以这种方式使用您的Web服务

$ curl localhost:8080/addCurrency/EUR

注：欧元是欧元的货币名称