scala基础API

1.对象和json转换

1.1 json取值

val json:JSONObject = JSON.parseObject(jsonMsg:String)
val message:String = json.getString("message")

1.2 json转对象

val student:Student = JSON.parseObject[Student](json:String, classOf[Student])

1.3 json转array对象

import scala.collection.JavaConverters._

val javaList = JSON.parseArray[ColumnValue](columnList, classOf[ColumnValue])
val colValueList = javaList.asScala

<dependency>
     <groupId>com.alibaba</groupId>
     <artifactId>fastjson</artifactId>
     <version>1.2.</version>
</dependency>

2.时间戳转换日期

import org.apache.commons.lang.time.FastDateFormat

val yearMonthDayHour：String = FastDateFormat.getInstance("yyyyMMddHH").format(timeStamp：Long)

3.比较大小

Math.max(element.timeStamp, preiodicTimeStamp)

DataStream[Object]转DataStream[String]

import org.json4s.DefaultFormats
import org.json4s.native.Serialization.write

val value: DataStream[Student]
val DataStreamStr: DataStream[String] = value.map {
      //进行json格式转换
      log => {
        //导入隐式转换
        implicit val formats = DefaultFormats
        val str = write(log)
        str
      }
    }