使用spark mongodb的casbah库，我能够完成我希望的操作。

import java.sql.Timestamp
import java.util.Date

import com.mongodb.casbah.MongoClient
import com.mongodb.casbah.commons.MongoDBObject
import com.mongodb.casbah.query.Imports._

object TestCasbah {

  def main(args: Array[String]) {
    val mongoClient = MongoClient("172.18.96.45", 27017)
    val db = mongoClient("agentCallRecord")
    val coll = db("CallDetails")
    val query = MongoDBObject("agentId" -> "agent_1")
    val callRatingMongoObject = MongoDBObject("audioId" -> 12351,"startTime" -> new Timestamp(new Date().getTime).toString, "endTime" -> new Timestamp(new Date().getTime).toString, "totalScore" -> 1, "sentiment" -> "NEGATIVE")
    val update = $push("callRating" -> callRatingMongoObject)
    coll.update(query, update)
  }
}