关于android：在Kotlin中使用Gson解析JSON数组

Using Gson in Kotlin to parse JSON array

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)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

{
"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

从json数组[{}，{}…]到ArrayList

就像是：

1	fun getWeatherObjectArrayFromJson(jsonStr: String): ArrayList<WeatherObject &gt

gsonBuilder.registerTypeAdapter(ArrayList

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52

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：

尝试从chandil03解决方案，它正在工作！将测试json数组数据和函数放在此处：

试过了

1
2
3
4
5
6
7
8
9
10
11
12
13
14

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
}

在有例外

1
2
3

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：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71

[
{
"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
}
]

您需要在fromJson()函数调用中更改参数，如下所示：

1	val weatherList: List<WeatherObject> = gson.fromJson(stringReader , Array<WeatherObject>::class.java).toList()

您需要传递Array::class.java作为类类型，然后将结果转换为List。无需更改registerTypeAdapter()函数调用。

检查以下代码：

1
2
3
4
5
6
7
8
9
10
11
12
13

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
}