scala 自带json_scala中复杂对象转JSON和解析的方法
比如有一个复杂对象：
Map[Int, Map[Int, Double]]
需要将其转为JSON保存，之后再读取使用，试了几种方法，最后的方案是：
1、定义case class
2、所有的数据类型都转为String(避免不必要的麻烦，至少Map的key都要为String，不然会报错scala.MatchError)
3、Map必须是immutable.Map
代码如下
1、转json
import org.json4s.JsonDSL._
import org.json4s.jackson.JsonMethods._
import org.json4s.jackson.Serialization._
import org.json4s.jackson.Serialization
case class WOE(col: String, woe: Map[String, String])
implicit val formats = Serialization.formats(NoTypeHints)
val testMap = Map[String, String]()
testMap += ("1" -> "1.1")
val a = WOE("1", immutable.Map(testMap.toList:_*))
println(write(a))
输出{"col":"1","woe":{"1":"1.1"}}
2、解析json
implicit val formats = Serialization.formats(NoTypeHints)
val js =
"""
{"col":"1","woe":{"1":"1.1"}}
"""
val ab = parse(js).extract[WOE]
println(write(ab))
如果是List也可以
implicit val formats = Serialization.formats(NoTypeHints)
val b = new ListBuffer[WOE]
val testMap = Map[String, String]()
testMap += ("1" -> "1.1")
b += WOE("1", immutable.Map(testMap.toList:_*))
b += WOE("3", immutable.Map(testMap.toList:_*))
println(write(b))
val js =
"""
[{"col":"1","woe":{"1":"1.1"}},{"col":"3","woe":{"1":"1.1"}}]
"""
val ab = parse(js).extract[List[WOE]]
println(ab.toString)
之前整理的一些方法
1、scala自带的Json解析
scala 2.10(以上，其他版本不清楚)自带Json解析，scala.util.parsing.json.JSON
object转json
val testMap = Map[String, String]()
testMap += ("1" -> "2.034")
testMap += ("2" -> "2.0134")
println(scala.util.parsing.json.JSONObject(scala.collection.immutable.Map(testMap.toList: _*)))
但好像只能处理map，且map要转成immutable
2、fastjson
解析json
import com.alibaba.fastjson.JSON
object JsonDemo {
def main(args: Array[String]) {
val text = "{\"name\":\"name1\", \"age\":55}"
val json = JSON.parseObject(text)
println(json.get("name"))
println(json.get("age"))
}
}
再例如
import com.alibaba.fastjson.JSON
object Json {
def main(args: Array[String]): Unit = {
val str2 = "{\"et\":\"kanqiu_client_join\",\"vtm\":1435898329434,\"body\":{\"client\":\"866963024862254\",\"client_type\":\"android\",\"room\":\"NBA_HOME\",\"gid\":\"\",\"type\":\"\",\"roomid\":\"\"},\"time\":1435898329}"
val json=JSON.parseObject(str2)
//获取成员
val fet=json.get("et")
//返回字符串成员
val etString=json.getString("et")
//返回整形成员
val vtm=json.getInteger("vtm")
println(vtm)
//返回多级成员
val client=json.getJSONObject("body").get("client")
println(client)
在spark-steaming中,使用fast-json更加稳定,json-lib经常出现莫名问题,而且fastjson的解析速度更快.
object转json，首先必须要显式的定义参数，否则会报错
ambiguous reference to overloaded definition
1
例如：
val testMap = Map[String, String]()
testMap += ("1" -> "2.034")
testMap += ("2" -> "2.0134")
val a = JSON.toJSONString(testMap, true)
println(a)
不会报错，但是输出结果是奇怪的
{
"empty":false,
"sizeMapDefined":false,
"traversableAgain":true
}
3、json4s
object转json
val testMap = Map[String, String]()
testMap += ("1" -> "2.034")
testMap += ("2" -> "2.0134")
val jj = compact(render(testMap))
println(jj)
输出
[{"2":"2.0134"},{"1":"2.034"}]
如果都是String，复杂的Map结构也可以解析
val testMap = Map[String, Map[String, String]]()
val subMap = Map[String, String]()
subMap += ("1" -> "1.1")
testMap += ("1" -> subMap)
println(write(testMap))
输出{"1":{"1":"1.1"}}
但这样的形式不利于解析
再例如
implicit val formats = Serialization.formats(NoTypeHints)
val m = Map(
"name" -> "john doe",
"age" -> 18,
"hasChild" -> true,
"childs" -> List(
Map("name" -> "dorothy", "age" -> 5, "hasChild" -> false),
Map("name" -> "bill", "age" -> 8, "hasChild" -> false)))
val mm = Map(
"1" -> Map ("1"->"1.2")
)
println(write(a))
TEST
package com.dfssi.dataplatform.analysis.exhaust.alarm
import java.sql.Timestamp
import java.util
import com.alibaba.fastjson.serializer.SerializerFeature
import org.apache.spark.Logging
import org.json4s.NoTypeHints
//将要解析得数据
case class NeedEntity(val vin: String,
val downoutput: Double,
val collectTime: Long,
val lon: Double,
val lat: Double,
val failureList: java.util.List[Integer] = new util.ArrayList[Integer]()
) extends Serializable
//管理状态
//这是事件管理得 按照每个事件来处理
class OverLimitEvent(var vin: String,
var startTime: Long,
var startLon: Double,
var startLat: Double,
var eventType:String="overlimit",
var endTime: Long = 0,
var endLon: Double = 0.0,
var endLat: Double = 0.0,
var minValue: Double = 0.0,
var maxValue: Double = 0.0
) extends Serializable with Logging{
def getInsertMap(): Map[String, Any] = {
Map(
"vin" -> vin,
"startTime" -> new Timestamp(startTime),
"startLon" -> startLon,
"startLat" -> startLat
)
}
def getUpdateMap(): Map[String, Any] = {
Map(
"vin" -> vin,
"startTime" -> new Timestamp(startTime),
"endTime" -> new Timestamp(startTime),
"endLon" -> startLon,
"endLat" -> startLat,
"maxValue" -> maxValue,
"minValue" -> minValue
)
}
def updateByEntity(entity: NeedEntity) = {
this.endTime = entity.collectTime
this.endLat = entity.lat
this.endLon = entity.lon
if (this.maxValue != null && this.maxValue < entity.downoutput) {
this.maxValue = entity.downoutput
}
if (this.minValue != null && this.minValue > entity.downoutput) {
this.minValue = entity.downoutput
}
}
override def toString(): String ={
import org.json4s.jackson.Serialization._
import org.json4s.jackson.Serialization
implicit val formats = Serialization.formats(NoTypeHints)
write(this)
}
}
object OverLimitEvent {
val ID_FIELD = Array("vin", "startTime")
def apply(
vin: String,
startTime: Long,
startLon: Double,
startLat: Double,
endTime: Long,
endLon: Double,
endLat: Double,
minValue: Double,
maxValue: Double
): OverLimitEvent = {
val event = new OverLimitEvent(vin, startTime, startLon, startLat)
event.endTime = endTime
event.endLat = endLat
event.endLon = endLon
event.maxValue = maxValue
event.minValue = minValue
event
}
def buildByEntity(entity: NeedEntity): OverLimitEvent = {
new OverLimitEvent(entity.vin, entity.collectTime, entity.lon, entity.lat)
}
def buildByJson(json: String): OverLimitEvent = {
com.alibaba.fastjson.JSON.parseObject(json, classOf[OverLimitEvent])
}
override def toString(): String ={
import org.json4s.jackson.Serialization._
import org.json4s.jackson.Serialization
implicit val formats = Serialization.formats(NoTypeHints)
write(this)
}
}
case class ExhaustAlarmStatus(val vin: String, var overLimitEvent: OverLimitEvent=null,var faultEvent:Map[String,OverLimitEvent]=null, var lastTime: Long) {
override def toString(): String ={
import org.json4s.jackson.Serialization._
import org.json4s.jackson.Serialization
implicit val formats = Serialization.formats(NoTypeHints)
write(this)
}
}
object ExhaustAlarmStatus {
def buildByJson(json: String): ExhaustAlarmStatus = {
if(json!=null){
com.alibaba.fastjson.JSON.parseObject(json,
classOf[ExhaustAlarmStatus])
}else{
null
}
}
def toJSON(state: ExhaustAlarmStatus): String = com.alibaba.fastjson.JSON.toJSONString(state, SerializerFeature.PrettyFormat)
def main(args: Array[String]): Unit = {
val json = "{\"vin\":\"222\", \"OverLimitEvent\":{ \"vin\":\"222\", \"startTime\":123456789, \"startLon\":1.0, \"startLat\":1.0, \"endTime\":123456789, \"endLon\":1.0, \"endLat\":1.0, \"minValue\":1.0, \"maxValue\":1.0 },\"lastTime\":1556441242000}";
val state = com.alibaba.fastjson.JSON.parseObject(json,
classOf[ExhaustAlarmStatus])
println(state.overLimitEvent)
import org.json4s.JsonDSL._
import org.json4s.jackson.JsonMethods._
import org.json4s.jackson.Serialization._
import org.json4s.jackson.Serialization
implicit val formats = Serialization.formats(NoTypeHints)
val jsonstr = write(state)
println(jsonstr)
}
}