在Kotlin中使用Gson解析JSON数组 [英] Using Gson in Kotlin to parse JSON array
问题描述
尝试在Kotlin中解析JSON数组，使其可用于单个JSON对象到WeatherObject对象(下面的代码段)
Trying to parse JSON array in Kotlin, made it work for single JSON object to a WeatherObject object (code snippet below)
{
"coord": {
"lon": -2.93,
"lat": 43.26
},
"weather": [{
"id": 802,
"main": "Clouds",
"description": "scattered clouds",
"icon": "03d"
}],
"main": {
"temp": 283.681,
"temp_min": 283.681,
"temp_max": 283.681,
"pressure": 991.72,
"sea_level": 1034.92,
"grnd_leve": 991.72,
"humidity": 98
},
"wind": {
"speed": 1.07,
"deg": 144.001
},
"dt": 1429773245,
"id": 3128026,
"name": "Bilbao",
"cod": 200
}
但不确定如果JSON是相同JSON对象的数组，即
but not sure how to do the same if the JSON is a array of same JSON object, i.e.
从json数组[{}，{}…]到ArrayList< WeatherObject>
from json array [ {}, {} …] to ArrayList<WeatherObject >
类似:
fun getWeatherObjectArrayFromJson(jsonStr: String): ArrayList<WeatherObject >
gsonBuilder.registerTypeAdapter(ArrayList< WeatherObject& gt :: class.java，WeatherDeserializer())出现问题
having problem with gsonBuilder.registerTypeAdapter(ArrayList<WeatherObject >::class.java, WeatherDeserializer())
class WeatherObject {
var main: String = ""
var description: String = ""
var temp: Float = 0.0f
var tempMax: Float = 0.0f
var tempMin: Float = 0.0f
var humidity: Int = 0
var wind: WindObject? = null
}
class WeatherDeserializer : JsonDeserializer<WeatherObject> {
override fun deserialize(json: JsonElement?, typeOfT: Type?, context: JsonDeserializationContext?): WeatherObject? {
val jsonObj = json as JsonObject
val wheather = WeatherObject()
val wind = WindObject()
val jsonWeatherArray = jsonObj.getAsJsonArray("weather").get(0)
val jsonMainObj = jsonObj.getAsJsonObject("main")
val jsonWindObj = jsonObj.getAsJsonObject("wind")
wheather.main = jsonWeatherArray.asJsonObject.get("main").asString
wheather.description = jsonWeatherArray.asJsonObject.get("description").asString
wheather.temp = jsonMainObj.get("temp").asFloat
wheather.tempMax = jsonMainObj.get("temp_max").asFloat
wheather.tempMin = jsonMainObj.get("temp_min").asFloat
wheather.humidity = jsonMainObj.get("humidity").asInt
wind.speed = jsonWindObj.get("speed").asFloat
wind.deg = jsonWindObj.get("deg").asFloat
wheather.wind = wind
return wheather
}
}
fun getWeatherObjectFromJson(jsonStr: String): WeatherObject {
var stringReader: StringReader = StringReader(jsonStr)
var jsonReader: JsonReader = JsonReader(stringReader)
val gsonBuilder = GsonBuilder().serializeNulls()
gsonBuilder.registerTypeAdapter(WeatherObject::class.java, WeatherDeserializer())
val gson = gsonBuilder.create()
val weather: WeatherObject = gson.fromJson(jsonReader, WeatherObject::class.java)
return weather
}
更新:
尝试了chandil03的解决方案，它正在工作！将测试json数组数据和函数放在此处:
tried the solution from chandil03, IT IS WORKING! put the testing json array data and the function here:
尝试
fun getWeatherObjectFromJsonArray(jsonArrayStr: String): List<WeatherObject> {
var stringReader: StringReader = StringReader(jsonStr)
//var jsonReader: JsonReader = JsonReader(stringReader)
val gsonBuilder = GsonBuilder().serializeNulls()
gsonBuilder.registerTypeAdapter(WeatherObject::class.java, WeatherDeserializer())
val gson = gsonBuilder.create()
val weatherList: List<WeatherObject> = gson.fromJson(stringReader , Array<WeatherObject>::class.java).toList()
//val weatherList: List<WeatherObject> = gson.fromJson(jsonReader, Array<WeatherObject>::class.java).toList
return weatherList
}
在
val weatherList: List<WeatherObject> = gson.fromJson(stringReader , Array<WeatherObject>::class.java).toList()
com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $
json数组数据如下:
the json array data is like:
[
{
"coord": {
"lon": -2.93,
"lat": 43.26
},
"weather": [{
"id": 802,
"main": "Clouds",
"description": "scattered clouds",
"icon": "03d"
}],
"main": {
"temp": 283.681,
"temp_min": 283.681,
"temp_max": 283.681,
"pressure": 991.72,
"sea_level": 1034.92,
"grnd_leve": 991.72,
"humidity": 98
},
"wind": {
"speed": 1.07,
"deg": 144.001
},
"clouds": {
"all": 36
},
"dt": 1429773245,
"id": 3128026,
"name": "Bilbao",
"cod": 200
},
{
"coord": {
"lon": -2.93,
"lat": 43.26
},
"weather": [{
"id": 802,
"main": "Clouds",
"description": "scattered clouds",
"icon": "03d"
}],
"main": {
"temp": 283.681,
"temp_min": 283.681,
"temp_max": 283.681,
"pressure": 991.72,
"sea_level": 1034.92,
"grnd_leve": 991.72,
"humidity": 98
},
"wind": {
"speed": 1.07,
"deg": 144.001
},
"clouds": {
"all": 36
},
"dt": 1429773245,
"id": 3128026,
"name": "Bilbao",
"cod": 200
}
]
推荐答案
您需要在fromJson()函数调用中更改参数，如下所示:
You need to change parameter in your fromJson() function call like following:
val weatherList: List<WeatherObject> = gson.fromJson(stringReader , Array<WeatherObject>::class.java).toList()
您需要为类类型传递Array<WeatherObject>::class.java，然后将结果转换为List.无需更改registerTypeAdapter()函数调用.
You need to pass Array<WeatherObject>::class.java for class type and then convert result into List. No need to change registerTypeAdapter() function call.
检查以下代码:
fun getWeatherObjectFromJson(jsonStr: String): List<WeatherObject> {
var stringReader: StringReader = StringReader(jsonStr)
var jsonReader: JsonReader = JsonReader(stringReader)
val gsonBuilder = GsonBuilder().serializeNulls()
gsonBuilder.registerTypeAdapter(WeatherObject::class.java, WeatherDeserializer())
val gson = gsonBuilder.create()
val weatherList: List<WeatherObject> = gson.fromJson(stringReader , Array<WeatherObject>::class.java).toList()
return weatherList
}
这篇关于在Kotlin中使用Gson解析JSON数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
