java - 无法使用 Retrofit 从 API 检索键/值对

Question

我需要显示从 API 获得的键(货币)/值对，例如货币的简称及其值。不幸的是，当我尝试获取模型类的任何值时，它显示为空。我该如何解决这个问题？

我正在使用的API是https://api.exchangeratesapi.io/

我应该收到的数据看起来像这样

{
  "base": "EUR",
  "rates": {
    "BGN": 1.9558,
    "NZD": 1.7025,
    "ILS": 4.0004,
    "RUB": 73.3493,
    "CAD": 1.5132,
    "USD": 1.123,
    "PHP": 58.722,
    "CHF": 1.1378,
    "ZAR": 15.9762,
    "AUD": 1.6059,
    "JPY": 123.25,
    "TRY": 6.8837,
    "HKD": 8.8135,
    "MYR": 4.6781,
    "THB": 35.464,
    "HRK": 7.409,
    "NOK": 9.8193,
    "IDR": 16177.38,
    "DKK": 7.4658,
    "CZK": 25.732,
    "HUF": 323.52,
    "GBP": 0.8625,
    "MXN": 21.5589,
    "KRW": 1325.32,
    "ISK": 137.0,
    "SGD": 1.5305,
    "BRL": 4.4405,
    "PLN": 4.296,
    "INR": 78.6075,
    "RON": 4.7598,
    "CNY": 7.6628,
    "SEK": 10.8108
  },
  "date": "2019-05-10"
}

主要 Activity :

public class MainActivity extends AppCompatActivity {

    TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView = findViewById(R.id.label);

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://api.exchangeratesapi.io/")
                .addConverterFactory(GsonConverterFactory.create())
                .build();

        Api api = retrofit.create(Api.class);
        Call<Model.Rates> call = api.getRates();

        call.enqueue(new Callback<Model.Rates>() {
            @Override
            public void onResponse(Call<Model.Rates> call, Response<Model.Rates> response) {
                if (!response.isSuccessful()){
                    textView.setText(response.code());
                    return;
                }

                List<Model.Rates> ratesList = Collections.singletonList(response.body());

                for (Model.Rates model : ratesList){
                    String content = "";
                    content += "First "+model.getCAD()+"\n\n\n";
                    textView.append(content);
                }
            }

            @Override
            public void onFailure(Call<Model.Rates> call, Throwable t) {
                textView.setText(t.getMessage());
            }
        });
    }
}

模型类:

public class Model {

    private String date;

    public Rates rates;

    private String base;

    private String currencyNationality;
    private String currencyValue;

    public Model(String currencyNationality, String currencyValue) {
        this.currencyNationality = currencyNationality;
        this.currencyValue = currencyValue;
    }

    public String getCurrencyNationality() {
        return currencyNationality;
    }

    public void setCurrencyNationality(String currencyNationality) {
        this.currencyNationality = currencyNationality;
    }

    public String getCurrencyValue() {
        return currencyValue;
    }

    public void setCurrencyValue(String currencyValue) {
        this.currencyValue = currencyValue;
    }

    public String getDate() {
        return date;
    }

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

    public Rates getRates() {
        return rates;
    }

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

    public String getBase() {
        return base;
    }

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

    class Rates {

        private String CHF;

        private String HRK;

        private String MXN;

        private String ZAR;

        private String INR;

        private String THB;

        private String CNY;

        private String AUD;

        private String ILS;

        private String KRW;

        private String JPY;

        private String PLN;

        private String GBP;

        private String IDR;

        private String HUF;

        private String PHP;

        private String TRY;

        private String RUB;

        private String HKD;

        private String ISK;

        private String DKK;

        private String CAD;

        private String USD;

        private String MYR;

        private String BGN;

        private String NOK;

        private String RON;

        private String SGD;

        private String CZK;

        private String SEK;

        private String NZD;

        private String BRL;

        public String getCHF() {
            return CHF;
        }

        public void setCHF(String CHF) {
            this.CHF = CHF;
        }

        public String getHRK() {
            return HRK;
        }

        public void setHRK(String HRK) {
            this.HRK = HRK;
        }

        public String getMXN() {
            return MXN;
        }

        public void setMXN(String MXN) {
            this.MXN = MXN;
        }

        public String getZAR() {
            return ZAR;
        }

        public void setZAR(String ZAR) {
            this.ZAR = ZAR;
        }

        public String getINR() {
            return INR;
        }

        public void setINR(String INR) {
            this.INR = INR;
        }

        public String getTHB() {
            return THB;
        }

        public void setTHB(String THB) {
            this.THB = THB;
        }

        public String getCNY() {
            return CNY;
        }

        public void setCNY(String CNY) {
            this.CNY = CNY;
        }

        public String getAUD() {
            return AUD;
        }

        public void setAUD(String AUD) {
            this.AUD = AUD;
        }

        public String getILS() {
            return ILS;
        }

        public void setILS(String ILS) {
            this.ILS = ILS;
        }

        public String getKRW() {
            return KRW;
        }

        public void setKRW(String KRW) {
            this.KRW = KRW;
        }

        public String getJPY() {
            return JPY;
        }

        public void setJPY(String JPY) {
            this.JPY = JPY;
        }

        public String getPLN() {
            return PLN;
        }

        public void setPLN(String PLN) {
            this.PLN = PLN;
        }

        public String getGBP() {
            return GBP;
        }

        public void setGBP(String GBP) {
            this.GBP = GBP;
        }

        public String getIDR() {
            return IDR;
        }

        public void setIDR(String IDR) {
            this.IDR = IDR;
        }

        public String getHUF() {
            return HUF;
        }

        public void setHUF(String HUF) {
            this.HUF = HUF;
        }

        public String getPHP() {
            return PHP;
        }

        public void setPHP(String PHP) {
            this.PHP = PHP;
        }

        public String getTRY() {
            return TRY;
        }

        public void setTRY(String TRY) {
            this.TRY = TRY;
        }

        public String getRUB() {
            return RUB;
        }

        public void setRUB(String RUB) {
            this.RUB = RUB;
        }

        public String getHKD() {
            return HKD;
        }

        public void setHKD(String HKD) {
            this.HKD = HKD;
        }

        public String getISK() {
            return ISK;
        }

        public void setISK(String ISK) {
            this.ISK = ISK;
        }

        public String getDKK() {
            return DKK;
        }

        public void setDKK(String DKK) {
            this.DKK = DKK;
        }

        public String getCAD() {
            return CAD;
        }

        public void setCAD(String CAD) {
            this.CAD = CAD;
        }

        public String getUSD() {
            return USD;
        }

        public void setUSD(String USD) {
            this.USD = USD;
        }

        public String getMYR() {
            return MYR;
        }

        public void setMYR(String MYR) {
            this.MYR = MYR;
        }

        public String getBGN() {
            return BGN;
        }

        public void setBGN(String BGN) {
            this.BGN = BGN;
        }

        public String getNOK() {
            return NOK;
        }

        public void setNOK(String NOK) {
            this.NOK = NOK;
        }

        public String getRON() {
            return RON;
        }

        public void setRON(String RON) {
            this.RON = RON;
        }

        public String getSGD() {
            return SGD;
        }

        public void setSGD(String SGD) {
            this.SGD = SGD;
        }

        public String getCZK() {
            return CZK;
        }

        public void setCZK(String CZK) {
            this.CZK = CZK;
        }

        public String getSEK() {
            return SEK;
        }

        public void setSEK(String SEK) {
            this.SEK = SEK;
        }

        public String getNZD() {
            return NZD;
        }

        public void setNZD(String NZD) {
            this.NZD = NZD;
        }

        public String getBRL() {
            return BRL;
        }

        public void setBRL(String BRL) {
            this.BRL = BRL;
        }

        List<Model> getCurrencyValuesList() {

            List<Model> currencyValues = new ArrayList<>();
            currencyValues.add(new Model("BGN", getAUD()));
            currencyValues.add(new Model("NZD", getNZD()));
            currencyValues.add(new Model("ILS", getILS()));
            currencyValues.add(new Model("RUB", getRUB()));
            currencyValues.add(new Model("CAD", getCAD()));
            currencyValues.add(new Model("USD", getUSD()));
            currencyValues.add(new Model("PHP", getPHP()));
            currencyValues.add(new Model("CHF", getCHF()));
            currencyValues.add(new Model("ZAR", getZAR()));
            currencyValues.add(new Model("AUD", getAUD()));
            currencyValues.add(new Model("JPY", getJPY()));
            currencyValues.add(new Model("TRY", getTRY()));
            currencyValues.add(new Model("HKD", getHKD()));
            currencyValues.add(new Model("MYR", getMYR()));
            currencyValues.add(new Model("THB", getTHB()));
            currencyValues.add(new Model("HRK", getHRK()));
            currencyValues.add(new Model("NOK", getNOK()));
            currencyValues.add(new Model("IDR", getIDR()));
            currencyValues.add(new Model("DKK", getDKK()));
            currencyValues.add(new Model("CZK", getCZK()));
            currencyValues.add(new Model("HUF", getHUF()));
            currencyValues.add(new Model("GBP", getBGN()));
            currencyValues.add(new Model("KRW", getKRW()));
            currencyValues.add(new Model("ISK", getISK()));
            currencyValues.add(new Model("SGD", getSGD()));
            currencyValues.add(new Model("BRL", getBRL()));
            currencyValues.add(new Model("PLN", getPLN()));
            currencyValues.add(new Model("INR", getINR()));
            currencyValues.add(new Model("RON", getRON()));
            currencyValues.add(new Model("CNY", getCNY()));
            currencyValues.add(new Model("SEK", getSEK()));
            return currencyValues;
        }
    }
}

API 类:

public interface Api {

    @GET("latest")
    Call<Model.Rates> getRates();
}

Answer 1

你的映射有点错误，我建议你采用这种方式。我创建了名为“货币”的类，而不是您的模型类。您可以重命名它或使用相同的

public class Currency {

@SerializedName("base") private String base;
@SerializedName("rates") private Map<String, Double> rates;

public String getBase() {
    return base;
}

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

public Map<String, Double> getRates() {
    return rates;
}

public void setRates(Map<String, Double> rates) {
    this.rates = rates;
}

}