java - JSONObject 到 ArrayList 方括号丢失

Question

我正在尝试将 https://api.ratesapi.io/api/latest 中的费率转换为自定义 ArrayList<Currency> 类的 Currency:

public class Currency {
    private String shortName;
    private double rate;
    ...
}

JSON 看起来像:

{"base":"EUR","rates":{"GBP":0.90033,"HKD":9.1786,"IDR":17304.0,
 "ILS":4.0309,"DKK":7.45,"INR":88.765,"CHF":1.0759,"MXN":26.615,
 "CZK":26.202,"SGD":1.6236,"THB":36.832,"HRK":7.468,"MYR":4.9604,
 "NOK":10.6538,"CNY":8.2325,"BGN":1.9558,"PHP":58.136,"SEK":10.3165,
 "PLN":4.4073,"ZAR":20.7655,"CAD":1.5748,"ISK":160.2,"BRL":6.334,
 "RON":4.836,"NZD":1.7828,"TRY":8.5853,"JPY":124.96,"RUB":86.9321,
 "KRW":1404.99,"USD":1.1843,"HUF":346.23,"AUD":1.6492},"date":"2020-08-06"}

使用 org.json 我设法将数据放入 JSONObject :

JSONObject obj = new JSONObject(getJSON("https://api.ratesapi.io/api/latest"));

据我了解，现在的正常程序是将 JSONObject 转换为 JSONArray 。但是尝试:

JSONArray jsonArray = obj.getJSONArray("rates");

失败并显示错误消息:

Exception in thread "main" org.json.JSONException: JSONObject["rates"]
is not a JSONArray.

如何修复此错误，或者是否有另一种方法可以从 JSON 中生成 ArrayList？
我怀疑问题在于 JSON 字符串中缺少方括号。

Answer 1

如果您查看 API 返回的 JSON，您会得到一个 JSON 对象:

{"base":"EUR","rates":{"GBP":0.90033,"HKD":9.1786, ... },"date":"2020-08-06"}

你可能想做这样的事情:

JSONObject obj = new JSONObject(getJSON("https://api.ratesapi.io/api/latest"));
JSONObject rates = obj.getJSONObject("rates");
final Iterator<String> keys = rates.keys();
while (keys.hasNext()) {
  final String key = keys.next();
  final Currency currency = new Currency(key, rates.getDouble(key));
  // do something with the Currency
}