Java 将 JSON 路径值解析为变量

Question

我有问题。我有以下代码将 JSON 字符串解析为对象：

public AgentStrategy parseJsonToObject(String jsonString) {
    Gson gson = new Gson();
    AgentStrategy agent = gson.fromJson(jsonString, AgentStrategy.class);    
    return agent;
}

但现在我有一个 JSON 值不等于属性名称。这是新的 JSON：

{
   "Market": "USDT",
   "Coin":"BTC",
   "ModuleEnabled":{
      "Patterns":{
         "Buy":"true",
         "Sell":"true"
      },
      "EMA":{
         "Buy":"true",
         "Sell":"false"
      }
   }
}

这就是类的样子：

public class AgentStrategy {

    public String Market;    
    public String Coin;

    public boolean ModuleEnabledBuyEMA;
    public boolean ModuleEnabledSellEMA;
    public boolean ModuleEnabledBuyPatterns;
    public boolean ModuleEnabledSellPatterns;

    public AgentStrategy parseJsonToObject(String jsonString) {
        Gson gson = new Gson();
        AgentStrategy agent = gson.fromJson(jsonString, AgentStrategy.class);

        return agent;
    }
}

现在如何匹配 JSON 和类如下：

"ModuleEnabled" -> "EMA" -> "Buy" = ModuleEnabledBuyEMA
"ModuleEnabled" -> "EMA" -> "Sell" = ModuleEnabledSellEMA
"ModuleEnabled" -> "Patterns" -> "Buy" = ModuleEnabledBuyPatterns
"ModuleEnabled" -> "Patterns" -> "Sell" = ModuleEnabledSellPatterns

Answer 1

您可以编写自定义反序列化器，在其中使用默认 Gson 反序列化并另外手动解析“有问题的”字段：

public class AgentStrategyDeserializer implements JsonDeserializer<AgentStrategy> {

    @Override
    public AgentStrategy deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {

        Gson gson = new Gson();
        AgentStrategy agent = gson.fromJson(jsonElement, AgentStrategy.class);
        // At this point only Market and Coin attributes are set. Since the booleans can not be parsed they are initialized to false

        JsonObject moduleEnabledJsonObject = jsonElement.getAsJsonObject().get("ModuleEnabled").getAsJsonObject();
        boolean moduleEnabledBuyPatterns = moduleEnabledJsonObject.get("Patterns").getAsJsonObject().get("Buy").getAsBoolean();
        boolean moduleEnabledSellPatterns = moduleEnabledJsonObject.get("Patterns").getAsJsonObject().get("Sell").getAsBoolean();
        boolean moduleEnabledBuyEMA = moduleEnabledJsonObject.get("EMA").getAsJsonObject().get("Buy").getAsBoolean();
        boolean moduleEnabledSellEMA = moduleEnabledJsonObject.get("EMA").getAsJsonObject().get("Sell").getAsBoolean();

        agent.setModuleEnabledBuyEMA(moduleEnabledBuyEMA);
        agent.setModuleEnabledSellEMA(moduleEnabledSellEMA);
        agent.setModuleEnabledBuyPatterns(moduleEnabledBuyPatterns);
        agent.setModuleEnabledSellPatterns(moduleEnabledSellPatterns);

        return agent;
    }
}

这就是你使用反序列化器的方式：

    GsonBuilder gsonBuilder = new GsonBuilder();
    gsonBuilder.registerTypeAdapter(AgentStrategy.class, new AgentStrategyDeserializer());
    Gson gson = gsonBuilder.create();
    AgentStrategy agentStrategy = gson.fromJson(jsonString, AgentStrategy.class);

Answer 2

第一个选择是编写自己的反序列化器。看： How do I write a custom JSON deserializer for Gson?

另一种解决方案是创建一个与您的 json 匹配的类，而不是创建一个方法(from(JsonMatchingClass)) 将其转换为 AgentStrategy