我正在使用scala、spark和kafka。我有两个问题。
1.如何确认kafka broker（服务器）中存在该主题？
2.如何确认kafka服务器（引导服务器）是否正在运行？

object kafkaProducer extends App {

  def sendMessages(): Unit = {

//define topic
val topic = "spark-topic"       // how can i confirm this topic is exist in kafka server ? 

//define producer properties
val props = new java.util.Properties()
props.put("bootstrap.servers", "localhost:9092")
props.put("client.id", "KafkaProducer")
props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer")
props.put("value.serializer", "org.apache.kafka.connect.json.JsonSerializer")

//create producer instance
val kafkaProducer = new KafkaProducer[String, JsonNode](props)

//create object mapper
val mapper = new ObjectMapper with ScalaObjectMapper
mapper.registerModule(DefaultScalaModule)
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)

//mapper Json object to string
      def toJson(value: Any): String = {
        mapper.writeValueAsString(value)
      }

//send producer message

    val jsonstring =
      s"""{
         | "id": "0001",
         | "name": "Peter"
         |}
      """.stripMargin

    val jsonNode: JsonNode = mapper.readTree(jsonstring)
    val rec = new ProducerRecord[String, JsonNode](topic, jsonNode)
    kafkaProducer.send(rec)
    //println(rec)

  }

}