Cassandra Database(4) Kryo?

Really useful document, I need to read them when I have time if I plan to deal with cassandra database.
http://www.datastax.com/documentation/cassandra/1.2/index.html?pagename=docs&version=1.2&file=index

1. Kryo Introduce
The latest version from the official website is 2.21. Adding to build.sbt

I only try a simple example for java HashMap
package com.sillycat.easycassandraserver.apps

import com.esotericsoftware.kryo.Kryo
import com.esotericsoftware.kryo.io.{Input, Output}
import java.util.{ HashMap => JMap }

object KryoDemoApp extends App{

? //java HashMap
? val maps = new JMap[String, Any]()
? maps.put("productName", "iphone4s")
? maps.put("price", 21.33)

? val kryo = new Kryo

? //transfer HashMap to bytes
? val out1 = new Output(new Array[Byte](4096))
? kryo.writeObject(out1, maps)
? out1.close
? val outputBytes1 = out1.toBytes
? println("outputBytes1 of Map = " + outputBytes1)

? //read the bytes back to HashMap
? val in1 = new Input(outputBytes1)
? val outputMap1 = kryo.readObject(in1,classOf[JMap[String, Any]])
? in1.close

? println("outputMap1 of Map = " + outputMap1)

}

The output should be as follow:
outputBytes1 of Map = [B@6581ed9e
outputMap1 of Map = {price=21.33, pro