java客户端连接kafka简单测试

本案例kafka版本是kafka_2.11-0.9.0.1，用java来实现kafka生产者、消费者的示例
在测试的过程中遇到的特别的问题以及解决办法，其他小问题就不一一列举了。

1 . 使用kafka-clients进行测试，maven依赖

<dependency>         <groupId>org.apache.kafka</groupId>         <artifactId>kafka-clients</artifactId>         <version>0.9.0.1</version>    </dependency>

需要注意：kafka-clients的版本必须和kafka安装的版本一致
2 . Consumer测试类收不到消息的原因：

①. 先开启consumer测试类，等待poll数据。
②. 开启producer测试类，发送数据，并确保发送成功。
③. 正常情况下这样就可以收到数据了。

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生产者示例

public class ProducerTest {    private void execMsgSend() throws  Exception{        Properties props = new Properties();        props.put("bootstrap.servers", "阿里云外网Ip:9092");        props.put("acks", "1");        props.put("retries", 0);        props.put("batch.size", 16384);        props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");        props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");        Producer<String, String> procuder = new KafkaProducer<String, String>(props);        String topic = "test";        for (int i = 1; i <= 10; i++) {            String value = " this is another message_" + i;            ProducerRecord<String,String> record = new ProducerRecord<String, String>(topic,i+"",value);            procuder.send(record,new Callback() {                @Override                public void onCompletion(RecordMetadata metadata, Exception exception) {                    System.out.println("message send to partition " + metadata.partition() + ", offset: " + metadata.offset());                }            });            System.out.println(i+" ----   success");            Thread.sleep(1000);        }        System.out.println("send message over.");        procuder.close();    }    public static void main(String[] args) throws  Exception{        ProducerTest test1 = new ProducerTest();        test1.execMsgSend();    }}

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消费者示例

public class Consumer {    public static void main(String[] s){          Properties props = new Properties();        props.put("bootstrap.servers", "阿里云外网Ip:9092");           props.put("group.id", "1");        props.put("enable.auto.commit", "true");        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<>(props);        consumer.subscribe(Arrays.asList("test"));        while (true) {            System.out.println("poll start...");            ConsumerRecords<String, String> records = consumer.poll(100);            int count = records.count();            System.out.println("the numbers of topic:" + count);            for (ConsumerRecord<String, String> record : records)                System.out.printf("offset = %d, key = %s, value = %s", record.offset(), record.key(), record.value());        }   }  }