Question

我写过简单的货币转换器，它从网络服务中读取JSON，并在网站上以选定的比率准备表格。

到目前为止，我的费率类为每个比率都有字段，但我决定将其更改为Map。我使用Map重写了整个课程，但RestTemplate无法将JSON数据映射到我的HashMap。整个字段被视为null。如何重新配置RestTemplate或ObjectMapper以将JSON映射到Map？

Example JSON string that I am trying to map

我用来读取JSON并将其映射到对象上的存储库类： package com.github.gromo13.currencyConverter.repository;

import com.github.gromo13.currencyConverter.model.Currency;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.web.client.RestTemplate;

@Repository
public class FixerIoCurrencyRepository implements CurrencyRepository {
    @Autowired
    private RestTemplate restTemplate;

    public void setRestTemplate(RestTemplate restTemplate) {
        this.restTemplate = restTemplate;
    }

    @Override
    public Currency getCurrency(String currencyCode) {
        Currency currency = restTemplate.getForObject("http://api.fixer.io/latest?base={currencyCode}", Currency.class, currencyCode);

        return currency;
    }
}

货币类我使用JSON数据进行映射： package com.github.gromo13.currencyConverter.model;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties(ignoreUnknown = true)
public class Currency {
    private String base;
    private String date;
    private Rates rates;

    public String getBase() {
        return this.base;
    }

    public void setBase(String base) {
        this.base = base;
    }

    public String getDate() {
        return this.date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public Rates getRates() {
        return this.rates;
    }

    public void setRates(Rates rates) {
        this.rates = rates;
    }
}

使用我无法映射的Map的费率类（货币类中的字段）： package com.github.gromo13.currencyConverter.model; import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

import java.util.HashMap;
import java.util.Map;

@JsonIgnoreProperties(ignoreUnknown = true)
public class Rates {
    private Map<String, Double> rates = new HashMap<>();

    public void clear() {
        rates.clear();
    }

    public void setRate(String currencyCode, double rate) {
        rates.put(currencyCode.toUpperCase(), rate);
    }

    public double getRate(String currencyCode) {
        return rates.get(currencyCode.toUpperCase());
    }
}

我的实际RestTemplate配置： package com.github.gromo13.currencyConverter.config;

import com.fasterxml.jackson.databind.MapperFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.client.RestTemplate;

@Configuration
public class Config {
    @Bean
    public RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.getMessageConverters().add(0, mappingJackson2HttpMessageConverter());

        return restTemplate;
    }

    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true);

        return mapper;
    }

    @Bean
    public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        converter.setObjectMapper(objectMapper());

        return converter;
    }
}

Answer 1

它不会像现在这样运作。你不需要private Map<String, Double> rates类，你可以完全摆脱它并使用：

if (someParam1 != 0)
{
    myQuery = myQuery.Where(q => q.SomeField1 == someParam1)
}
if (someParam2 != 0)
{
    myQuery = myQuery.Where(q => q.SomeField2 == someParam2)
}

在货币类中。

RestTemplate映射到Map而不是字段

1 个答案: