如何创建Kafka客户端：Avro Producer和Consumer Client

1.目标 - Kafka客户端

在本文的Kafka客户端中，我们将学习如何使用Kafka API 创建Apache Kafka客户端。有几种方法可以创建Kafka客户端，例如最多一次，至少一次，以及一次性消息处理需求。因此，在这个Kafka客户端教程中，我们将学习所有三种方式的详细描述。此外，我们将详细介绍如何使用Avro客户端。

那么，让我们开始Kafka客户端教程。

如何创建Kafka客户端：Avro Producer和Consumer Client

2. Kafka客户是什么？

• 创建Kafka客户端的先决条件

1. 最初，为了创建Kafka客户端，我们必须在本地计算机上设置Apache Kafka中间件。 
2. 此外，在开始创建Kafka客户端之前，本地安装的单个节点Kafka实例必须与我们的本地机器一起运行，并且需要运行Zookeeper和arning Kafka节点。

学习Apache Kafka用例| Kafka应用程序
此外，在Kafka客户端中创建一个名为normal-topic的主题，其中包含两个分区，命令为：

bin/kafka-topics --zookeeper localhost:2181 --create --topic normal-topic --partitions 2 --replication-factor 1

1. bin / kafka-topics --zookeeper localhost：2181 --create --topic normal-topic --partitions 2 --rerelication -factor 1

此外，执行以下命令，以检查创建的主题的状态：

bin/kafka-topics --list --topic normal-topic --zookeeper localhost:2181

1. bin / kafka-topics --list --topic normal-topic --zookeeper localhost：2181

此外，要在需要更改主题时增加分区，请执行以下命令：

bin/kafka-topics.sh --alter --topic normal-topic --zookeeper localhost:2181 --partitions 2

1. bin / kafka-topics.sh --alter --topic normal-topic --zookeeper localhost：2181 --partitions 2

3.卡夫卡制片人客户

这里是以下代码来实现Kafka生产者客户端。它将有助于发送文本消息并调整循环以控制需要发送以创建Kafka客户端的消息数量：

public class ProducerExample {
   public static void main(String[] str) throws InterruptedException, IOException {
           System.out.println("Starting ProducerExample ...");
           sendMessages();
   }
   private static void sendMessages() throws InterruptedException, IOException {
           Producer<String, String> producer = createProducer();
           sendMessages(producer);
           // Allow the producer to complete sending of the messages before program exit.
           Thread.sleep(20);
   }
   private static Producer<String, String> createProducer() {
       Properties props = new Properties();
       props.put("bootstrap.servers", "localhost:9092");
       props.put("acks", "all");
       props.put("retries", 0);
       // Controls how much bytes sender would wait to batch up before publishing to Kafka.
       props.put("batch.size", 10);
       props.put("linger.ms", 1);
       props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
       props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
       return new KafkaProducer(props);
   }
   private static void sendMessages(Producer<String, String> producer) {
       String topic = "normal-topic";
       int partition = 0;
       long record = 1;
       for (int i = 1; i <= 10; i++) {
           producer.send(
               new ProducerRecord<String, String>(topic, partition,                                 Long.toString(record),Long.toString(record++)));
       }
   }
}

4.消费者可以注册Kafka

首先，让我们学习几种方法，Kafka消费者客户可以通过这种方式向Kafka经纪人注册。具体来说，有两种方法，使用subscribe方法调用或使用assign方法调用。让我们详细了解这两种Kafka客户端方法。

一个。使用订阅方法调用

使用订阅方法调用时，Kafka会在添加/删除主题或分区时，或者在添加或删除使用者时自动重新平衡可用的使用者。

湾 使用分配方法调用。

但是，当消费者使用assign方法调用注册时，Kafka客户端不提供消费者的自动重新平衡。
让我们修改Kafka架构及其基本概念
上述任何一种注册选项都可以被最多一次，至少一次或完全一次的消费者使用。
一世。最多一次卡夫卡消费者（零次或多次交付）
基本上，这是卡夫卡消费者的默认行为。
要在Kafka客户端中配置此类型的使用者，请按照下列步骤操作：

• 首先，将'enable.auto.commit'设置为true。
• 另外，将'auto.commit.interval.ms'设置为较低的时间范围。
• 确保不要调用consumer.commitSync（）; 来自消费者。此外，Kafka将使用此消费者配置以指定的时间间隔自动提交偏移量。

然而，消费者有可能表现出最多一次或至少一次的行为，而消费者则以这种方式配置。虽然，让我们将此消费者声明为最多一次，因为最多一次是较低的消息传递保证。让我们详细讨论两种消费者行为：

• 最多一次的情景

发生提交间隔的时刻，以及触发Kafka自动提交上次使用的偏移的时刻，这种情况发生。但是，让我们假设消息和消费者在处理之间崩溃了。然后，当消费者重新启动时，它开始从最后提交的偏移量接收消息。同时，消费者可能会丢失一些消息。
探索卡夫卡的优势与劣势

• 至少一次的情况

当消费者处理消息并将消息提交到其持久存储中时，消费者在此时崩溃，这种情况发生。但是，让我们假设Kafka没有机会向代理提交偏移，因为提交间隔还没有通过。然后，当消费者重新启动时，它会从最后一个提交的偏移量中获得一些较旧的消息。
卡夫卡消费者代码：

public class AtMostOnceConsumer {
       public static void main(String[] str) throws InterruptedException {
           System.out.println("Starting  AtMostOnceConsumer ...");
           execute();
       }
       private static void execute() throws InterruptedException {
               KafkaConsumer<String, String> consumer = createConsumer();
               // Subscribe to all partition in that topic. 'assign' could be used here
               // instead of 'subscribe' to subscribe to specific partition.
               consumer.subscribe(Arrays.asList("normal-topic"));
               processRecords(consumer);
       }
       private static KafkaConsumer<String, String> createConsumer() {
               Properties props = new Properties();
               props.put("bootstrap.servers", "localhost:9092");
               String consumeGroup = "cg1";
               props.put("group.id", consumeGroup);
               // Set this property, if auto commit should happen.
               props.put("enable.auto.commit", "true");
               // Auto commit interval, kafka would commit offset at this interval.
               props.put("auto.commit.interval.ms", "101");
               // This is how to control number of records being read in each poll
               props.put("max.partition.fetch.bytes", "135");
               // Set this if you want to always read from beginning.
               // props.put("auto.offset.reset", "earliest");
               props.put("heartbeat.interval.ms", "3000");
               props.put("session.timeout.ms", "6001");
               props.put("key.deserializer",
                       "org.apache.kafka.common.serialization.StringDeserializer");
               props.put("value.deserializer",
                       "org.apache.kafka.common.serialization.StringDeserializer");
               return new KafkaConsumer<String, String>(props);
       }
       private static void processRecords(KafkaConsumer<String, String> consumer)  {
               while (true) {
                       ConsumerRecords<String, String> records = consumer.poll(100);
                       long lastOffset = 0;
                       for (ConsumerRecord<String, String> record : records) {
                               System.out.printf("

offset = %d, key = %s, value = %s", record.offset(),                                             record.key(), record.value());
                              lastOffset = record.offset();
                        }
               System.out.println("lastOffset read: " + lastOffset);
               process();
               }
       }
       private static void process() throws InterruptedException {
               // create some delay to simulate processing of the message.
               Thread.sleep(20);
       }
}

II。至少一次Kafka Consumer（一个或多个消息传递，可能重复）
为了配置此类型的使用者，请按照下列步骤操作：

• 首先，将'enable.auto.commit'设置为false或
• 另外，将'enable.auto.commit'设置为true，将'auto.commit.interval.ms'设置为更高的数字。

通过调用consumer.commitSync（），Consumer现在应该控制消息偏移提交给Kafka; 
此外，为了避免重复消息的重新处理，在消费者中实现“幂等”行为，尤其是对于这种类型的消费者，因为在以下场景中，可能发生重复的消息传递。
我们来讨论Apache Kafka Security | Kafka代码的需求和组成部分
：

public class AtLeastOnceConsumer {
   public static void main(String[] str) throws InterruptedException {
           System.out.println("Starting AutoOffsetGuranteedAtLeastOnceConsumer ...");
           execute();
    }
   private static void execute() throws InterruptedException {
           KafkaConsumer<String, String> consumer = createConsumer();
           // Subscribe to all partition in that topic. 'assign' could be used here
           // instead of 'subscribe' to subscribe to specific partition.
           consumer.subscribe(Arrays.asList("normal-topic"));
           processRecords(consumer);
    }
    private static KafkaConsumer<String, String> createConsumer() {
           Properties props = new Properties();
           props.put("bootstrap.servers", "localhost:9092");
           String consumeGroup = "cg1";
           props.put("group.id", consumeGroup);
           // Set this property, if auto commit should happen.
           props.put("enable.auto.commit", "true");
           // Make Auto commit interval to a big number so that auto commit does not happen,
           // we are going to control the offset commit via consumer.commitSync(); after processing             // message.
           props.put("auto.commit.interval.ms", "999999999999");
           // This is how to control number of messages being read in each poll
           props.put("max.partition.fetch.bytes", "135");
           props.put("heartbeat.interval.ms", "3000");
           props.put("session.timeout.ms", "6001");
           props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
           props.put("value.deserializer","org.apache.kafka.common.serialization.StringDeserializer");
           return new KafkaConsumer<String, String>(props);
   }
    private static void processRecords(KafkaConsumer<String, String> consumer) throws {
           while (true) {
                   ConsumerRecords<String, String> records = consumer.poll(100);
                   long lastOffset = 0;
                   for (ConsumerRecord<String, String> record : records) {
                       System.out.printf("

offset = %d, key = %s, value = %s", record.offset(),                                         record.key(), record.value());
                       lastOffset = record.offset();
                   }
                   System.out.println("lastOffset read: " + lastOffset);
                   process();
                   // Below call is important to control the offset commit. Do this call after you
                   // finish processing the business process.
                   consumer.commitSync();
           }
   }
   private static void process() throws InterruptedException {
       // create some delay to simulate processing of the record.
       Thread.sleep(20);
   }
}

III。通过订阅（一个且只有一个消息传递）完全一次Kafka动态消费者
这里，通过'subscribe'（1，a）注册方法调用，消费者向Kafka注册。
确保在这种情况下应手动管理偏移量。要在Kafka客户端中设置完全一次的方案，请按照下列步骤操作：

• 首先，设置enable.auto.commit = false。
• 处理完消息后，请勿调用consumer.commitSync（）。
• 此外，通过进行“订阅”调用，将消费者注册到主题。
• 要从该主题/分区的特定偏移量开始读取，请实现ConsumerRebalanceListener。此外，在侦听器中执行consumer.seek（topicPartition，offset）。
• 作为安全网，实施幂等。

码：

public class ExactlyOnceDynamicConsumer {
      private static OffsetManager offsetManager = new OffsetManager("storage2");
       public static void main(String[] str) throws InterruptedException {
               System.out.println("Starting ExactlyOnceDynamicConsumer ...");
               readMessages();
       }
       private static void readMessages() throws InterruptedException {
               KafkaConsumer<String, String> consumer = createConsumer();
               // Manually controlling offset but register consumer to topics to get dynamically
               // assigned partitions. Inside MyConsumerRebalancerListener use
               // consumer.seek(topicPartition,offset) to control offset which messages to be read.
               consumer.subscribe(Arrays.asList("normal-topic"),
                               new MyConsumerRebalancerListener(consumer));
               processRecords(consumer);
       }
       private static KafkaConsumer<String, String> createConsumer() {
               Properties props = new Properties();
               props.put("bootstrap.servers", "localhost:9092");
               String consumeGroup = "cg3";
               props.put("group.id", consumeGroup);
               // To turn off the auto commit, below is a key setting.
               props.put("enable.auto.commit", "false");
               props.put("heartbeat.interval.ms", "2000");
               props.put("session.timeout.ms", "6001");
               // Control maximum data on each poll, make sure this value is bigger than the maximum                   // single message size
               props.put("max.partition.fetch.bytes", "140");
               props.put("key.deserializer",                                 "org.apache.kafka.common.serialization.StringDeserializer");
               props.put("value.deserializer",                         "org.apache.kafka.common.serialization.StringDeserializer");
               return new KafkaConsumer<String, String>(props);
       }
       private static void processRecords(KafkaConsumer<String, String> consumer)
           while (true) {
                   ConsumerRecords<String, String> records = consumer.poll(100);
                   for (ConsumerRecord<String, String> record : records) {
                           System.out.printf("offset = %d, key = %s, value = %s
", record.offset(),                                     record.key(), record.value());
                           // Save processed offset in external storage.
                           offsetManager.saveOffsetInExternalStore(record.topic(), record.partition(),                                             record.offset());
                   }
              }
       }
}
public class MyConsumerRebalancerListener implements                                 org.apache.kafka.clients.consumer.ConsumerRebalanceListener {
       private OffsetManager offsetManager = new OffsetManager("storage2");
       private Consumer<String, String> consumer;
       public MyConsumerRebalancerListener(Consumer<String, String> consumer) {
               this.consumer = consumer;
       }
       public void onPartitionsRevoked(Collection<TopicPartition> partitions) {
               for (TopicPartition partition : partitions) {
                   offsetManager.saveOffsetInExternalStore(partition.topic(), partition.partition(),                     consumer.position(partition));
               }
       }
       public void onPartitionsAssigned(Collection<TopicPartition> partitions) {
               for (TopicPartition partition : partitions) {
                       consumer.seek(partition,                             offsetManager.readOffsetFromExternalStore(partition.topic(),                             partition.partition()));
               }
       }
}
/**
* The partition offset are stored in an external storage. In this case in a local file system where
* program runs.
*/
public class OffsetManager {
       private String storagePrefix;
       public OffsetMpublic class ExactlyOnceDynamicConsumer {
      private static OffsetManager offsetManager = new OffsetManager("storage2");
       public static void main(String[] str) throws InterruptedException {
               System.out.println("Starting ExactlyOnceDynamicConsumer ...");
               readMessages();
       }
       private static void readMessages() throws InterruptedException {
               KafkaConsumer<String, String> consumer = createConsumer()
               // Manually controlling offset but register consumer to topics to get dynamically
               // assigned partitions. Inside MyConsumerRebalancerListener use
               // consumer.seek(topicPartition,offset) to control offset which messages to be read.
               consumer.subscribe(Arrays.asList("normal-topic"),
                              new MyConsumerRebalancerListener(consumer));
               processRecords(consumer);
       }
       private static KafkaConsumer<String, String> createConsumer() {
               Properties props = new Properties();
               props.put("bootstrap.servers", "localhost:9092");
               String consumeGroup = "cg3";
               props.put("group.id", consumeGroup);
               // To turn off the auto commit, below is a key setting.
               props.put("enable.auto.commit", "false");
               props.put("heartbeat.interval.ms", "2000");
               props.put("session.timeout.ms", "6001");
               // Control maximum data on each poll, make sure this value is bigger than the maximum                   // single message size
               props.put("max.partition.fetch.bytes", "140");
               props.put("key.deserializer",                                 "org.apache.kafka.common.serialization.StringDeserializer");
               props.put("value.deserializer",                         "org.apache.kafka.common.serialization.StringDeserializer");
               return new KafkaConsumer<String, String>(props);
       }
       private static void processRecords(KafkaConsumer<String, String> consumer) {
           while (true) {
                   ConsumerRecords<String, String> records = consumer.poll(100);
                   for (ConsumerRecord<String, String> record : records) {
                           System.out.printf("offset = %d, key = %s, value = %s
", record.offset(),                                     record.key(), record.value());
                           // Save processed offset in external storage.
                           offsetManager.saveOffsetInExternalStore(record.topic(), record.partition(),                                             record.offset());
                   }
              }
       }
}
public class MyConsumerRebalancerListener implements                                 org.apache.kafka.clients.consumer.ConsumerRebalanceListener {
       private OffsetManager offsetManager = new OffsetManager("storage2");
       private Consumer<String, String> consumer;
       public MyConsumerRebalancerListener(Consumer<String, String> consumer) {
               this.consumer = consumer;
       }
       public void onPartitionsRevoked(Collection<TopicPartition> partitions) {
               for (TopicPartition partition : partitions) {
                   offsetManager.saveOffsetInExternalStore(partition.topic(), partition.partition(),                     consumer.position(partition));
               }
       }
       public void onPartitionsAssigned(Collection<TopicPartition> partitions) {
               for (TopicPartition partition : partitions) {
                       consumer.seek(partition,                             offsetManager.readOffsetFromExternalStore(partition.topic(),                             partition.partition()));
               }
       }
}
/**
* The partition offset are stored in an external storage. In this case in a local file system where
* program runs.
*/
public class OffsetManager {
       private String storagePrefix;
       public OffsetManager(String storagePrefix) {
               this.storagePrefix = storagePrefix;
       }
   /**
       * in an external storage, overwrite the offset for the topic.
       *
       * @param topic - Topic name.
       * @param partition - Partition of the topic.
       * @param offset - offset to be stored.
       */
       void saveOffsetInExternalStore(String topic, int partition, long offset) {
           try {
               FileWriter writer = new FileWriter(storageName(topic, partition), false);
               BufferedWriter bufferedWriter = new BufferedWriter(writer);
               bufferedWriter.write(offset + "");
               bufferedWriter.flush();
               bufferedWriter.close();
           } catch (Exception e) {
                   e.printStackTrace();
                   throw new RuntimeException(e);
           }
       }
       /**
           * @return he last offset + 1 for the provided topic and partition.
       */
       long readOffsetFromExternalStore(String topic, int partition) {
               try {
                       Stream<String> stream = Files.lines(Paths.get(storageName(topic, partition)));
                       return Long.parseLong(stream.collect(Collectors.toList()).get(0)) + 1;
               } catch (Exception e) {
                   e.printStackTrace();
               }
               return 0;
       }
       private String storageName(String topic, int partition) {
           return storagePrefix + "-" + topic + "-" + partition;
       }
}
anager(String storagePrefix) {
               this.storagePrefix = storagePrefix;
       }
   /**
       * in an external storage, overwrite the offset for the topic.
       *
       * @param topic - Topic name.
       * @param partition - Partition of the topic.
       * @param offset - offset to be stored.
       */
       void saveOffsetInExternalStore(String topic, int partition, long offset) {
           try {
               FileWriter writer = new FileWriter(storageName(topic, partition), false);
               BufferedWriter bufferedWriter = new BufferedWriter(writer);
               bufferedWriter.write(offset + "");
               bufferedWriter.flush();
               bufferedWriter.close();
           } catch (Exception e) {
                   e.printStackTrace();
                   throw new RuntimeException(e);
           }
       }
       /**
           * @return he last offset + 1 for the provided topic and partition.
       */
       long readOffsetFromExternalStore(String topic, int partition) {
               try {
                       Stream<String> stream = Files.lines(Paths.get(storageName(topic, partition)));
                       return Long.parseLong(stream.collect(Collectors.toList()).get(0)) + 1;
               } catch (Exception e) {
                   e.printStackTrace();
               }
               return 0;
       }
       private String storageName(String topic, int partition) {
           return storagePrefix + "-" + topic + "-" + partition;
       }
}

看看Storm Kafka与配置和代码的集成
iv。完全一次Kafka静态消费者通过分配（一次和一次消息传递）
这里，通过'assign（2）注册方法调用，消费者向Kafka客户注册。
确保在这种情况下应手动管理偏移量。要通过Assign设置Exactly-once Kafka Static Consumer，请按照下列步骤操作：

• 首先，设置enable.auto.commit = false
• 请记住，在处理完消息后，请不要调用consumer.commitSync（）。
• 此外，通过使用'assign'调用，将consumer注册到特定分区。
• 通过调用consumer.seek（topicPartition，offset），在消费者启动时寻找特定的消息偏移量。
• 另外，作为安全网，实施幂等。

码：

public class ExactlyOnceStaticConsumer {
       private static OffsetManager offsetManager = new OffsetManager("storage1");
       public static void main(String[] str) throws InterruptedException, IOException {
               System.out.println("Starting ExactlyOnceStaticConsumer ...");
               readMessages();
       }
       private static void readMessages() throws InterruptedException, IOException {
               KafkaConsumer<String, String> consumer = createConsumer();
               String topic = "normal-topic";
               int partition =1;
               TopicPartition topicPartition =
                               registerConsumerToSpecificPartition(consumer, topic, partition);
               // Read the offset for the topic and partition from external storage.
               long offset = offsetManager.readOffsetFromExternalStore(topic, partition);
               // Use seek and go to exact offset for that topic and partition.
               consumer.seek(topicPartition, offset);
               processRecords(consumer);
       }
       private static KafkaConsumer<String, String> createConsumer() {
               Properties props = new Properties();
               props.put("bootstrap.servers", "localhost:9092");
               String consumeGroup = "cg2";
               props.put("group.id", consumeGroup);
               // To turn off the auto commit, below is a key setting.
               props.put("enable.auto.commit", "false");
               props.put("heartbeat.interval.ms", "2000");
               props.put("session.timeout.ms", "6001");
               // control maximum data on each poll, make sure this value is bigger than the maximum                 // single message size
               props.put("max.partition.fetch.bytes", "140");
               props.put("key.deserializer",                                     "org.apache.kafka.common.serialization.StringDeserializer");
               props.put("value.deserializer",                                     "org.apache.kafka.common.serialization.StringDeserializer");
               return new KafkaConsumer<String, String>(props);
       }
       /**
           * Manually listens for specific topic partition. Now, see an example of how to                * dynamically listens to partition and want to manually control offset,
           * ExactlyOnceDynamicConsumer.java
           */
        private static TopicPartition registerConsumerToSpecificPartition(
                   KafkaConsumer<String, String> consumer, String topic, int partition) {
                   TopicPartition topicPartition = new TopicPartition(topic, partition);
                   List<TopicPartition> partitions = Arrays.asList(topicPartition);
                   consumer.assign(partitions);
                   return topicPartition;
         }
           /**
               * Process data and store offset in external store. Best practice is to do these operations
               * atomically.
               */
           private static void processRecords(KafkaConsumer<String, String> consumer) throws {
                   while (true) {
                          ConsumerRecords<String, String> records = consumer.poll(100);
                           for (ConsumerRecord<String, String> record : records) {
                                   System.out.printf("offset = %d, key = %s, value = %s
", record.offset(),                                                 record.key(), record.value());
                                   offsetManager.saveOffsetInExternalStore(record.topic(), record.partition(),                                                 record.offset());
                           }
                   }
           }
}

5. Avro制片人和消费者

在定义Avro时，它是一种开源二进制消息交换协议。基本上，为了通过线路发送优化的消息，这也减少了网络开销，我们使用它。此外，对于可以使用JSON定义的消息，Avro可以强制执行模式。通过使用这些模式，Avro可以使用各种编程语言生成绑定对象。将Avro与Kafka一起使用是本机支持的，也是强烈推荐的。
阅读Apache Kafka + Spark Streaming Integration
下面是一个简单的Avro消费者和制作人。

public class AvroConsumerExample {
       public static void main(String[] str) throws InterruptedException {
               System.out.println("Starting AutoOffsetAvroConsumerExample ...");
               readMessages();
       }
       private static void readMessages() throws InterruptedException {
               KafkaConsumer<String, byte[]> consumer = createConsumer();
               // Assign to specific topic and partition.
               consumer.assign(Arrays.asList(new TopicPartition("avro-topic", 0)));
               processRecords(consumer);
         }
         private static void processRecords(KafkaConsumer<String, byte[]> consumer) throws {
               while (true) {
                       ConsumerRecords<String, byte[]> records = consumer.poll(100);
                       long lastOffset = 0;
                       for (ConsumerRecord<String, byte[]> record : records) {
                               GenericRecord genericRecord                                        = AvroSupport.byteArrayToData(AvroSupport.getSchema(),                                             record.value());
                               String firstName = AvroSupport.getValue(genericRecord,                                             "firstName", String.class);
                               System.out.printf("

offset = %d, key = %s, value = %s", record.offset(),                                             record.key(), firstName);
                               lastOffset = record.offset();
                       }
                   System.out.println("lastOffset read: " + lastOffset);
                   consumer.commitSync();
               }
           }
           private static KafkaConsumer<String, byte[]> createConsumer() {
                       Properties props = new Properties();
                       props.put("bootstrap.servers", "localhost:9092");
                       String consumeGroup = "cg1";
                       props.put("group.id", consumeGroup);
                       props.put("enable.auto.commit", "true");
                       props.put("auto.offset.reset", "earliest");
                       props.put("auto.commit.interval.ms", "100");
                       props.put("heartbeat.interval.ms", "3000");
                       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.ByteArrayDeserializer");
                   return new KafkaConsumer<String, byte[]>(props);
           }
}
public class AvroProducerExample {
       public static void main(String[] str) throws InterruptedException, IOException {
               System.out.println("Starting ProducerAvroExample ...");
               sendMessages();
       }
       private static void sendMessages() throws InterruptedException, IOException {
               Producer<String, byte[]> producer = createProducer();
               sendRecords(producer);
       }
       private static Producer<String, byte[]> createProducer() {
                   Properties props = new Properties();
                   props.put("bootstrap.servers", "localhost:9092");
                   props.put("acks", "all");
                   props.put("retries", 0);
                   props.put("batch.size", 16384);
                   props.put("linger.ms", 1);
                   props.put("buffer.memory", 33554432);
                   props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
                   props.put("value.serializer",                                 "org.apache.kafka.common.serialization.ByteArraySerializer");
               return new KafkaProducer(props);
       }
       private static void sendRecords(Producer<String, byte[]> producer) throws IOException, {
               String topic = "avro-topic";
               int partition = 0;
               while (true) {
                       for (int i = 1; i < 100; i++)
                           producer.send(new ProducerRecord<String, byte[]>(topic, partition,                                     Integer.toString(0), record(i + "")));
               }
        }
        private static byte[] record(String name) throws IOException {
                   GenericRecord record = new GenericData.Record(AvroSupport.getSchema());
                   record.put("firstName", name);
                   return AvroSupport.dataToByteArray(AvroSupport.getSchema(), record);
         }
}

所以，这完全是关于Kafka客户端的。希望您喜欢我们对如何创建Kafka客户端的解释。

六，结论

因此，我们已经看到了使用Kafka API创建Kafka客户端的所有方法。此外，在这个Kafka Clients教程中，我们讨论了Kafka Producer Client，Kafka Consumer Client。除此之外，我们还了解了Avro Kafka Producer和Consumer Kafka客户。但是，如果对Kafka客户有任何疑问，请随时通过评论部分询问。