RestTemplate映射到Map而不是字段

Question

我編寫了一個簡單的貨幣轉換器，該轉換器從Web服務讀取JSON，並以選定的比率在網站上准備表格。

到目前為止，我的Rates類具有每個比率的字段，但是我決定將其更改為Map 。 我使用Map重寫了整個類，但RestTemplate無法將JSON數據映射到我的HashMap。 整個字段均視為null 。 如何重新配置RestTemplate或ObjectMapper以啟用將JSON映射到Map ？

我嘗試映射的示例JSON字符串

我正在使用的存儲庫類讀取JSON並將其映射到對象：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;
    }
}

我正在使用JSON數據映射貨幣類：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;
    }
}

我無法映射的Map費率類（Currency類中的字段）：package com.github.gromo13.currencyConverter.model; 導入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());
    }
}

我實際的RestTemplate配置：包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

它不會像現在那樣發揮作用。 您不需要Rates類，可以完全擺脫它並使用：

private Map<String, Double> rates

在貨幣類中。