Java 迭代 Map 值

Question

我有问题。我有以下 JSON：

{
   "Market":"USDT",
   "Coin":"BTC",
   "Period":"1h",
   "EmergencyPerc":-25,
   "TakeProfitPerc":1.2,
   "ProtectiveOrdersEnabled":"no",
   "EMACrossMarginPerc":0.08,
   "EMABuySellPeriod":"5m",
   "EMABuySellNameLow":"EMA5",
   "EMABuySellNameHigh":"EMA20",
   "EMAUnfreezePeriod":"1h",
   "EMAUnfreezeNameLow":"EMA20",
   "EMAUnfreezeNameHigh":"EMA200",
   "SimTemplate":"t001",
   "PriceDropSells":[
      {
         "Period":"3h",
         "Number":"4",
         "Perc":"-1.0"
      },
      {
         "Period":"1h",
         "Number":"2",
         "Perc":"-2.0"
      }
   ]
}

在我的 java 类中，我添加了以下代码以将 Json 作为对象解析为当前类：

public class AgentStrategy {

    private String market;
    private String coin;
    private String period;
    private double emergencyPerc;
    private double takeProfitPerc;
    private String protectiveOrdersEnabled;
    private double EMACrossMarginPerc;
    private String EMABuySellPeriod;
    private String EMABuySellNameLow;
    private String EMABuySellNameHigh;
    private String EMAUnfreezePeriod;
    private String EMAUnfreezeNameLow;
    private String EMAUnfreezeNameHigh;
    private String simTemplate;
    private ArrayList<AgentStrategyPriceDropSells> priceDropSells = new ArrayList<>();

    public AgentStrategy parseJsonToObject(String jsonString) {
        Gson gson = new Gson();

        gson.fromJson(jsonString, AgentStrategy.class);

        Map map = gson.fromJson(jsonString, Map.class);
        this.market = map.get("Market").toString();
        this.coin = map.get("Coin").toString();
        this.period = map.get("Period").toString();
        this.emergencyPerc = Double.parseDouble(map.get("EmergencyPerc").toString());
        this.takeProfitPerc = Double.parseDouble(map.get("TakeProfitPerc").toString());
        this.protectiveOrdersEnabled = map.get("ProtectiveOrdersEnabled").toString();
        this.EMACrossMarginPerc = Double.parseDouble(map.get("EMACrossMarginPerc").toString());
        this.EMABuySellPeriod = map.get("EMABuySellPeriod").toString();
        this.EMABuySellNameLow = map.get("EMABuySellNameLow").toString();
        this.EMABuySellNameHigh = map.get("EMABuySellNameHigh").toString();
        this.EMAUnfreezePeriod = map.get("EMAUnfreezePeriod").toString();
        this.EMAUnfreezeNameLow = map.get("EMAUnfreezeNameLow").toString();
        this.EMAUnfreezeNameHigh = map.get("EMAUnfreezeNameHigh").toString();
        this.simTemplate = map.get("SimTemplate").toString();


        // PRICE DROP SELLS
        Map priceDropSellsMap = (Map) map.get("PriceDropSells");
        // ???

        return this;
    }

    private class PriceDropSell {

        private String period;
        private String number;
        private double perc;

    }
}

该函数应该返回一个完全填充的对象，但我正在努力处理ArrayList<PriceDropSell>。问题是我不知道如何将我的 JSON 中的PriceDropSells 存储为ArrayList<PriceDropSell>。除了 PriceDropSell，每个字段都存储在 AgentStrategy 类中。如何将该部分解析为 ArrayList？

Answer 1

您不需要所有地图的东西。 Gson 会直接解析成对象。但请确保名称匹配：

class Test
{
    private class PriceDropSell {
        private String Period;
        private String Number;
        private double Perc;
    }
    public class AgentStrategy {
        private String Market;
        private String Coin;
        private String Period;
        private double EmergencyPerc;
        private double TakeProfitPerc;
        private String ProtectiveOrdersEnabled;
        private double EMACrossMarginPerc;
        private String EMABuySellPeriod;
        private String EMABuySellNameLow;
        private String EMABuySellNameHigh;
        private String EMAUnfreezePeriod;
        private String EMAUnfreezeNameLow;
        private String EMAUnfreezeNameHigh;
        private String SimTemplate;
        private ArrayList<PriceDropSell> PriceDropSells;
    }

    public static void main (String[] args) throws java.lang.Exception
    {
        BufferedReader bufferedReader = new BufferedReader(new FileReader(path_to_json_file));
        Gson gson = new Gson();
        AgentStrategy agent = gson.fromJson(bufferedReader, AgentStrategy.class);
        
        System.out.println(agent.PriceDropSells.get(0).Perc);
    }
}

Answer 2

为什么不检查“PriceDropSells”的实际对象是什么？只需在不进行任何强制转换的情况下获取该属性并使用调试器检查它的类型：

对象 priceDropSellsMap = map.get("PriceDropSells");

我想它应该是一个数组或一个列表。