谁能写一个简单的单例模式?

必须使用高亮参数启动spark-shell,否则当你遍历rdd时会出现如下的exception
java.io.notserializableexception: org.apache.hadoop.hbase.io.immutablebyteswritable
spark-shell--conf spark.serializer=org.apache.spark.serializer.kryoserializer
以下代码,经过maprdb实测通过
import org.apache.spark._
import org.apache.spark.rdd.newhadooprdd
import org.apache.hadoop.hbase.{hbaseconfiguration, htabledescriptor}
import org.apache.hadoop.hbase.client.hbaseadmin
import org.apache.hadoop.hbase.mapreduce.tableinputformat
import org.apache.hadoop.fs.path;
import org.apache.hadoop.hbase.hcolumndescriptor
import org.apache.hadoop.hbase.util.bytes
import org.apache.hadoop.hbase.client.put;
import org.apache.hadoop.hbase.client.htable;
val tablename = "/app/subscriptionbillingplatform/transac_id"
val conf = hbaseconfiguration.create()
conf.set(tableinputformat.input_table, tablename)
//create rdd
val hbaserdd = sc.newapihadooprdd(conf, classof[tableinputformat], 
  classof[org.apache.hadoop.hbase.io.immutablebyteswritable],
  classof[org.apache.hadoop.hbase.client.result])
hbaserdd.take(2).map(row=>row._2.rawcells).
      map(_.map( kv => (new string(kv.getqualifier()) -> new 
string(kv.getvalue()) ) ).tomap ).     foreach( map => { map.foreach{
 entry => print(entry._1 +":" + entry._2 + ", ")  } ; 
print("\n-----------\n") }  )       
//get the row count
val count = hbaserdd.count()
print("hbase rdd count:"+count)