累加器方法：Spark自定义累加器的使用实例详解

val sparkConf = new SparkConf().setAppName("Test").setMaster("local[2]") 
val sc = new SparkContext(sparkConf) 
val accum = sc.longAccumulator("longAccum") //统计奇数的个数 
val sum = sc.parallelize(Array(1,2,3,4,5,6,7,8,9),2).filter(n=>{ 
 if(n%2!=0) accum.add(1L)  
 n%2==0 
}).reduce(_+_) 
println("sum: "+sum) 
println("accum: "+accum.value) 
sc.stop() 

package spark
import constant.Constant
import org.apache.spark.util.AccumulatorV2
import util.getFieldFromConcatString
import util.setFieldFromConcatString
open class SessionAccmulator : AccumulatorV2<String, String>() {
  private var result = Constant.SESSION_COUNT + "=0|"+
      Constant.TIME_PERIOD_1s_3s + "=0|"+
      Constant.TIME_PERIOD_4s_6s + "=0|"+
      Constant.TIME_PERIOD_7s_9s + "=0|"+
      Constant.TIME_PERIOD_10s_30s + "=0|"+
      Constant.TIME_PERIOD_30s_60s + "=0|"+
      Constant.TIME_PERIOD_1m_3m + "=0|"+
      Constant.TIME_PERIOD_3m_10m + "=0|"+
      Constant.TIME_PERIOD_10m_30m + "=0|"+
      Constant.TIME_PERIOD_30m + "=0|"+
      Constant.STEP_PERIOD_1_3 + "=0|"+
      Constant.STEP_PERIOD_4_6 + "=0|"+
      Constant.STEP_PERIOD_7_9 + "=0|"+
      Constant.STEP_PERIOD_10_30 + "=0|"+
      Constant.STEP_PERIOD_30_60 + "=0|"+
      Constant.STEP_PERIOD_60 + "=0"
  override fun value(): String {
    return this.result
  }
  /**
   * 合并数据
   */
  override fun merge(other: AccumulatorV2<String, String>?) {
    if (other == null) return else {
      if (other is SessionAccmulator) {
        var newResult = ""
        val resultArray = arrayOf(Constant.SESSION_COUNT,Constant.TIME_PERIOD_1s_3s, Constant.TIME_PERIOD_4s_6s, Constant.TIME_PERIOD_7s_9s,
            Constant.TIME_PERIOD_10s_30s, Constant.TIME_PERIOD_30s_60s, Constant.TIME_PERIOD_1m_3m,
            Constant.TIME_PERIOD_3m_10m, Constant.TIME_PERIOD_10m_30m, Constant.TIME_PERIOD_30m,
            Constant.STEP_PERIOD_1_3, Constant.STEP_PERIOD_4_6, Constant.STEP_PERIOD_7_9,
            Constant.STEP_PERIOD_10_30, Constant.STEP_PERIOD_30_60, Constant.STEP_PERIOD_60)
        resultArray.forEach {
          val oldValue = other.result.getFieldFromConcatString("|", it)
          if (oldValue.isNotEmpty()) {
            val newValue = oldValue.toInt() + 1
            //找到原因，一直在循环赋予值,debug30分钟 很烦
            if (newResult.isEmpty()){
              newResult = result.setFieldFromConcatString("|", it, newValue.toString())
            }
            //问题就在于这里，自定义没有写错，合并错了
            newResult = newResult.setFieldFromConcatString("|", it, newValue.toString())
          }
        }
        result = newResult
      }
    }
  }
  override fun copy(): AccumulatorV2<String, String> {
    val sessionAccmulator = SessionAccmulator()
    sessionAccmulator.result = this.result
    return sessionAccmulator
  }
  override fun add(p0: String?) {
    val v1 = this.result
    val v2 = p0
    if (v2.isNullOrEmpty()){
      return
    }else{
      var newResult = ""
      val oldValue = v1.getFieldFromConcatString("|", v2!!)
      if (oldValue.isNotEmpty()){
        val newValue = oldValue.toInt() + 1
        newResult = result.setFieldFromConcatString("|", v2, newValue.toString())
      }
      result = newResult
    }
  }
  override fun reset() {
    val newResult = Constant.SESSION_COUNT + "=0|"+
        Constant.TIME_PERIOD_1s_3s + "=0|"+
        Constant.TIME_PERIOD_4s_6s + "=0|"+
        Constant.TIME_PERIOD_7s_9s + "=0|"+
        Constant.TIME_PERIOD_10s_30s + "=0|"+
        Constant.TIME_PERIOD_30s_60s + "=0|"+
        Constant.TIME_PERIOD_1m_3m + "=0|"+
        Constant.TIME_PERIOD_3m_10m + "=0|"+
        Constant.TIME_PERIOD_10m_30m + "=0|"+
        Constant.TIME_PERIOD_30m + "=0|"+
        Constant.STEP_PERIOD_1_3 + "=0|"+
        Constant.STEP_PERIOD_4_6 + "=0|"+
        Constant.STEP_PERIOD_7_9 + "=0|"+
        Constant.STEP_PERIOD_10_30 + "=0|"+
        Constant.STEP_PERIOD_30_60 + "=0|"+
        Constant.STEP_PERIOD_60 + "=0"
    result = newResult
  }
  override fun isZero(): Boolean {
    val newResult = Constant.SESSION_COUNT + "=0|"+
        Constant.TIME_PERIOD_1s_3s + "=0|"+
        Constant.TIME_PERIOD_4s_6s + "=0|"+
        Constant.TIME_PERIOD_7s_9s + "=0|"+
        Constant.TIME_PERIOD_10s_30s + "=0|"+
        Constant.TIME_PERIOD_30s_60s + "=0|"+
        Constant.TIME_PERIOD_1m_3m + "=0|"+
        Constant.TIME_PERIOD_3m_10m + "=0|"+
        Constant.TIME_PERIOD_10m_30m + "=0|"+
        Constant.TIME_PERIOD_30m + "=0|"+
        Constant.STEP_PERIOD_1_3 + "=0|"+
        Constant.STEP_PERIOD_4_6 + "=0|"+
        Constant.STEP_PERIOD_7_9 + "=0|"+
        Constant.STEP_PERIOD_10_30 + "=0|"+
        Constant.STEP_PERIOD_30_60 + "=0|"+
        Constant.STEP_PERIOD_60 + "=0"
    return this.result == newResult
  }
}