在 Android 中使用 Gson 处理 Json 数组到 POJO 数组映射中的单个对象异常

Question

我正在从第三方 API 读取 Json 数组，并使用 Gson 将其直接映射到 POJO 数组。我经常会丢失某些对象的数据，并且所有缺少的参数都具有 "N/A" 值。

我的 POJO class 混合了 String 和 Double 变量，现在当 "N/A" 返回时 Double 值是预期的，应用程序崩溃.当然，我可以手动遍历它们并跳过缺少数据的对象，但我正在寻找替代解决方案来帮助我在使用 Gson 进行映射时做同样的事情。

POJO class（Kotlin 语法）

class StockData(
    var symbol: String?,
    var name: String?,
    var currency: String?,
    var price: Double,
    @SerializedName("day_change")
    var dayChange: Double,
    @SerializedName("change_pct")
    var changePct: Double,
    var price90DayHigh: Double,
    var price90DayLow: Double
)

映射

val stockDataList = Gson().fromJson(response.body()!!.asJsonObject.get("data"),
                    Array<StockData>::class.java).toList()

Json 有可用数据

{
    "symbol": "AAK.ST",
    "name": "AAK AB (publ)",
    "currency": "SEK",
    "price": "189.15",
    "price_open": "190.90",
    "day_high": "190.95",
    "day_low": "188.30",
    "52_week_high": "203.80",
    "52_week_low": "131.62",
    "day_change": "-1.35",
    "change_pct": "-0.71",
    "close_yesterday": "190.50",
    "market_cap": "47993210000",
    "volume": "110641",
    "volume_avg": "476416",
    "shares": "253730934",
    "stock_exchange_long": "Stockholm Stock Exchange",
    "stock_exchange_short": "OMX",
    "timezone": "CET",
    "timezone_name": "Europe/Stockholm",
    "gmt_offset": "3600",
    "last_trade_time": "2020-02-21 17:29:54",
    "pe": "32.60",
    "eps": "5.32"
}

Json 缺少数据

{
    "symbol": "HEMF-PREF.ST",
    "name": "N/A",
    "currency": "N/A",
    "price": "0.00",
    "price_open": "N/A",
    "day_high": "N/A",
    "day_low": "N/A",
    "52_week_high": "N/A",
    "52_week_low": "N/A",
    "day_change": "N/A",
    "change_pct": "N/A",
    "close_yesterday": "N/A",
    "market_cap": "N/A",
    "volume": "N/A",
    "volume_avg": "N/A",
    "shares": "N/A",
    "stock_exchange_long": "Stockholm Stock Exchange",
    "stock_exchange_short": "OMX",
    "timezone": "CET",
    "timezone_name": "Europe/Stockholm",
    "gmt_offset": "3600",
    "last_trade_time": "N/A",
    "pe": "N/A",
    "eps": "N/A"
}

Answer 1

有两种方式： 1.You 创建 GsonAdapter 适配器，例如

class StockDataAdapter: TypeAdapter<StockData> {
   fun read(reader: JsonReader): StockData {
      ....handle actual json parsing here, setting default value to field if parsing failed
    }
}

然后

val gson =GsonBuilder().registerTypeAdapter(StockData.class,  StockDataAdapter()).create();
val stockDataList = gson.fromJson(response.body()!!.asJsonObject.get("data"),
                Array<StockData>::class.java).toList()

您可以将所有字段设为 String 类型并就地解析实际值，例如

class 股票数据( val 符号：String?, 验证名称：字符串？， val currency: String?, 有效价格：字符串， @SerializedName("day_change") val dayChange：字符串？， @SerializedName("change_pct") val changePct：字符串， val price90DayHigh：字符串， val price90DayLow：字符串 ) { 瓦尔 priceAsDouble:Double get() = try {price.toDouble()}catch(e:Exception){0.0} }

在 Android 中使用 Gson 处理 Json 数组到 POJO 数组映射中的单个对象异常

Handle exception of single object in mapping of Json Array to POJO Array using Gson in Android

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kotlin