我从一个服务接收到一个相当深的JSON对象字符串,我必须解析为JSON对象,然后将其映射到类。

如何将JSON字符串转换为Kotlin对象?

在映射到各自的类之后,我使用了来自Jackson的StdDeserializer。当对象的属性也必须被反序列化为类时,问题就出现了。我无法在另一个反序列化器中获得对象映射器,至少我不知道如何获得。

最好是,在本地,我试图减少我需要的依赖项的数量,所以如果答案只是JSON操作和解析它就足够了。


当前回答

你可以使用Gson。

例子

步骤1

添加编译

compile 'com.google.code.gson:gson:2.8.2'

步骤2

将 json 转换为 Kotlin Bean(使用 JsonToKotlinClass)

像这样

Json数据

{
"timestamp": "2018-02-13 15:45:45",
"code": "OK",
"message": "user info",
"path": "/user/info",
"data": {
    "userId": 8,
    "avatar": "/uploads/image/20180115/1516009286213053126.jpeg",
    "nickname": "",
    "gender": 0,
    "birthday": 1525968000000,
    "age": 0,
    "province": "",
    "city": "",
    "district": "",
    "workStatus": "Student",
    "userType": 0
},
"errorDetail": null
}

科特林豆

class MineUserEntity {

    data class MineUserInfo(
        val timestamp: String,
        val code: String,
        val message: String,
        val path: String,
        val data: Data,
        val errorDetail: Any
    )

    data class Data(
        val userId: Int,
        val avatar: String,
        val nickname: String,
        val gender: Int,
        val birthday: Long,
        val age: Int,
        val province: String,
        val city: String,
        val district: String,
        val workStatus: String,
        val userType: Int
    )
}

步骤3

使用Gson

var gson = Gson()
var mMineUserEntity = gson?.fromJson(response, MineUserEntity.MineUserInfo::class.java)

其他回答

您可以使用这个库https://github.com/cbeust/klaxon

Klaxon是一个轻量级库,用于在Kotlin中解析JSON。

不知道这是不是你需要的但我就是这么做的。

使用import org.json.JSONObject:

    val jsonObj = JSONObject(json.substring(json.indexOf("{"), json.lastIndexOf("}") + 1))
    val foodJson = jsonObj.getJSONArray("Foods")
    for (i in 0..foodJson!!.length() - 1) {
        val categories = FoodCategoryObject()
        val name = foodJson.getJSONObject(i).getString("FoodName")
        categories.name = name
    }

下面是json的示例:

{“食品”: [{“食品名称”: “苹果”,“重量”: “110” } ]}

我个人在Kotlin中使用Jackson模块,您可以在这里找到:Jackson -module- Kotlin。

implementation "com.fasterxml.jackson.module:jackson-module-kotlin:$version"

举个例子,下面是解析《流放之路》技能树JSON的代码,它相当重(格式化时84k行):

芬兰湾的科特林代码:

package util

import com.fasterxml.jackson.databind.DeserializationFeature
import com.fasterxml.jackson.module.kotlin.*
import java.io.File

data class SkillTreeData( val characterData: Map<String, CharacterData>, val groups: Map<String, Group>, val root: Root,
                          val nodes: List<Node>, val extraImages: Map<String, ExtraImage>, val min_x: Double,
                          val min_y: Double, val max_x: Double, val max_y: Double,
                          val assets: Map<String, Map<String, String>>, val constants: Constants, val imageRoot: String,
                          val skillSprites: SkillSprites, val imageZoomLevels: List<Int> )


data class CharacterData( val base_str: Int, val base_dex: Int, val base_int: Int )

data class Group( val x: Double, val y: Double, val oo: Map<String, Boolean>?, val n: List<Int> )

data class Root( val g: Int, val o: Int, val oidx: Int, val sa: Int, val da: Int, val ia: Int, val out: List<Int> )

data class Node( val id: Int, val icon: String, val ks: Boolean, val not: Boolean, val dn: String, val m: Boolean,
                 val isJewelSocket: Boolean, val isMultipleChoice: Boolean, val isMultipleChoiceOption: Boolean,
                 val passivePointsGranted: Int, val flavourText: List<String>?, val ascendancyName: String?,
                 val isAscendancyStart: Boolean?, val reminderText: List<String>?, val spc: List<Int>, val sd: List<String>,
                 val g: Int, val o: Int, val oidx: Int, val sa: Int, val da: Int, val ia: Int, val out: List<Int> )

data class ExtraImage( val x: Double, val y: Double, val image: String )

data class Constants( val classes: Map<String, Int>, val characterAttributes: Map<String, Int>,
                      val PSSCentreInnerRadius: Int )

data class SubSpriteCoords( val x: Int, val y: Int, val w: Int, val h: Int )

data class Sprite( val filename: String, val coords: Map<String, SubSpriteCoords> )

data class SkillSprites( val normalActive: List<Sprite>, val notableActive: List<Sprite>,
                         val keystoneActive: List<Sprite>, val normalInactive: List<Sprite>,
                         val notableInactive: List<Sprite>, val keystoneInactive: List<Sprite>,
                         val mastery: List<Sprite> )

private fun convert( jsonFile: File ) {
    val mapper = jacksonObjectMapper()
    mapper.configure( DeserializationFeature.ACCEPT_EMPTY_ARRAY_AS_NULL_OBJECT, true )

    val skillTreeData = mapper.readValue<SkillTreeData>( jsonFile )
    println("Conversion finished !")
}

fun main( args : Array<String> ) {
    val jsonFile: File = File( """rawSkilltree.json""" )
    convert( jsonFile )

JSON(未格式化):http://filebin.ca/3B3reNQf3KXJ/rawSkilltree.json

根据你的描述,我相信符合你的需要。

解析JSON字符串到Kotlin对象

正如其他人推荐的那样,Gson库是最简单的方法!

如果文件在资产文件夹中,您可以这样做,首先添加

dependencies {
  implementation 'com.google.code.gson:gson:2.9.0'
}

然后从资产中获取一个文件:

jsonString = context.assets.open(fileName).bufferedReader().use { it.readText() }

然后使用Gson:

val gson = Gson()
val listPersonType = object : TypeToken<List<Person>>() {}.type
var persons: List<Person> = gson.fromJson(jsonFileString, listPersonType)
persons.forEachIndexed { idx, person -> Log.i("data", "> Item $idx:\n$person") }

Person是一个模型/数据类,像这样

data class Person(val name: String, val age: Int, val messages: List) {
}

从这里下载deme的源代码(Json解析在android kotlin)

添加这个依赖:

compile 'com.squareup.okhttp3:okhttp:3.8.1'

调用api函数:

 fun run(url: String) {
    dialog.show()
    val request = Request.Builder()
            .url(url)
            .build()

    client.newCall(request).enqueue(object : Callback {
        override fun onFailure(call: Call, e: IOException) {
            dialog.dismiss()

        }

        override fun onResponse(call: Call, response: Response) {
            var str_response = response.body()!!.string()
            val json_contact:JSONObject = JSONObject(str_response)

            var jsonarray_contacts:JSONArray= json_contact.getJSONArray("contacts")

            var i:Int = 0
            var size:Int = jsonarray_contacts.length()

            al_details= ArrayList();

            for (i in 0.. size-1) {
                var json_objectdetail:JSONObject=jsonarray_contacts.getJSONObject(i)


                var model:Model= Model();
                model.id=json_objectdetail.getString("id")
                model.name=json_objectdetail.getString("name")
                model.email=json_objectdetail.getString("email")
                model.address=json_objectdetail.getString("address")
                model.gender=json_objectdetail.getString("gender")

                al_details.add(model)


            }

            runOnUiThread {
                //stuff that updates ui
                val obj_adapter : CustomAdapter
                obj_adapter = CustomAdapter(applicationContext,al_details)
                lv_details.adapter=obj_adapter
            }

            dialog.dismiss()

        }

    })