kafka0.9版本以后用java重新编写了producer，废除了原来scala编写的版本。

这里直接使用最新2.3版本，0.9以后的版本都适用。

注意引用的包为：org.apache.kafka.clients.producer

import java.util.Properties;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
public class ProducerDemo {
    public static void main(String[] args) {
        Properties properties = new Properties();
        properties.put("bootstrap.servers", "kafka01:9092,kafka02:9092");
        properties.put("acks", "all");
        properties.put("retries", 0);
        properties.put("batch.size", 16384);
        properties.put("linger.ms", 1);
        properties.put("buffer.memory", 33554432);
        properties.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        properties.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        KafkaProducer<String, String> kafkaProducer = new KafkaProducer<String, String>(properties);
        kafkaProducer.send(new ProducerRecord<>("topic", "value"));
        kafkaProducer.close();
    }
    
}

0.11.0以后增加了事务，事务producer的示例代码如下，需要适用于0.11.0以后的版本：

import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.Producer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.KafkaException;
import org.apache.kafka.common.errors.AuthorizationException;
import org.apache.kafka.common.errors.OutOfOrderSequenceException;
import org.apache.kafka.common.errors.ProducerFencedException;
import org.apache.kafka.common.serialization.StringSerializer;
import java.util.Properties;
public class TransactionsProducerDemo {
    public static void main(String[] args) {
        Properties props = new Properties();
        props.put("bootstrap.servers", "localhost:9092");
        props.put("transactional.id", "my-transactional-id");
        Producer<String, String> producer = new KafkaProducer<>(props, new StringSerializer(), new StringSerializer());
        producer.initTransactions();
        try {
            producer.beginTransaction();
            for (int i = 0; i < 100; i++)
                producer.send(new ProducerRecord<>("my-topic", Integer.toString(i), Integer.toString(i)));
            producer.commitTransaction();
        } catch (ProducerFencedException | OutOfOrderSequenceException | AuthorizationException e) {
            // We can't recover from these exceptions, so our only option is to close the producer and exit.
            producer.close();
        } catch (KafkaException e) {
            // For all other exceptions, just abort the transaction and try again.
            producer.abortTransaction();
        }
        producer.close();
    }
    
}

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