我目前正在评估apachekafka，我有一个简单的使用者，它应该从特定的主题分区读取消息。这是我的客户：

public static void main(String args[]) {

    Properties props = new Properties();
    props.put("bootstrap.servers", "localhost:9092");
    props.put("group.id", "test");
    props.put("enable.auto.commit", "false");
    props.put("auto.commit.interval.ms", "1000");
    props.put("session.timeout.ms", "30000");
    props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
    props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");

    KafkaConsumer<String, String> consumer = new KafkaConsumer<String, String>(props);

    TopicPartition partition0 = new TopicPartition("test_topic", Integer.parseInt(args[0]));

    ArrayList topicAssignment = new ArrayList();
    topicAssignment.add(partition0);
    consumer.assign(topicAssignment);

    //consumer.subscribe(Arrays.asList("test_topic"));
    int commitInterval = 200;
    List<ConsumerRecord<String, String>> buffer = new ArrayList<ConsumerRecord<String, String>>();

    while (true) {
        ConsumerRecords<String, String> records = consumer.poll(100);
        for (ConsumerRecord<String, String> record : records) {
            buffer.add(record);
            if (buffer.size() >= commitInterval) {
                process(buffer);
                consumer.commitSync();
                buffer.clear();
            }
        }
    }
}

static void process(List<ConsumerRecord<String, String>> buffers) {
   for (ConsumerRecord<String, String> buffer : buffers) {
       System.out.println(buffer);
   }
}

下面是我用来启动apache kafka的命令：

bin/kafka-server-start.sh config/server.properties & bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 2 --partitions 2 --topic test_topic

正如您在这里看到的，我用两个分区（p0和p1）创建主题！
然后，我使用以下命令启动两个consumer示例：
对于消费者1：

java -cp target/scala-2.11/kafka-consumer-0.1.0-SNAPAHOT.jar com.test.api.consumer.KafkaConsumer09Java 0

对于消费者2：

java -cp target/scala-2.11/kafka-consumer-0.1.0-SNAPAHOT.jar com.test.api.consumer.KafkaConsumer09Java 1

其中0和1表示我希望我的消费者从中读取消息的实际分区。
但结果是只有我的消费者1得到了所有的信息。在我的印象中，来自生产者的消息在分区上是平等的。
我使用以下命令查看我的主题test\u topic有多少个分区：

Joes-MacBook-Pro:kafka_2.11-0.9.0.0 joe$ bin/kafka-run-class.sh kafka.tools.ConsumerOffsetChecker --broker-info --group test --topic test_topic --zookeeper localhost:2181
[2016-01-14 13:36:48,831] WARN WARNING: ConsumerOffsetChecker is deprecated and will be dropped in releases following 0.9.0. Use ConsumerGroupCommand instead. (kafka.tools.ConsumerOffsetChecker$)
Group           Topic                          Pid Offset          logSize         Lag             Owner
test            test_topic                     0   10000           10000           0               none
BROKER INFO
0 -> 172.22.4.34:9092

为什么只有一个分区，即使我告诉Kafka为test\u主题创建两个分区？
这是我的制作人：

def main(args: Array[String]) {
    //val conf = new SparkConf().setAppName("VPP metrics producer")
    //val sc = new SparkContext(conf)

    val props: Properties = new Properties()
      props.put("metadata.broker.list", "localhost:9092,localhost:9093")
      props.put("serializer.class", "kafka.serializer.StringEncoder")

    val config = new ProducerConfig(props)
    val producer = new Producer[String, String](config)

    1 to 10000 map {
      case i => 
        val jsonStr = getRandomTsDataPoint().toJson.toString
        println(s"sending message $i to kafka")
        producer.send(new KeyedMessage[String, String]("test_topic", jsonStr))
        println(s"sent message $i to kafka")
    }
  }