Kafka - 异步/同步发送API

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异步发送

普通异步发送

需求：创建Kafka生产者，采用异步的方式发送到Kafka broker

异步发送流程

Code

<!-- https://mvnrepository.com/artifact/org.apache.kafka/kafka-clients -->
<dependency><groupId>org.apache.kafka</groupId><artifactId>kafka-clients</artifactId><version>3.6.0</version>
</dependency>

package com.artisan.pc;import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;
import org.apache.kafka.common.serialization.StringSerializer;import java.util.Properties;
import java.util.concurrent.ExecutionException;/*** @author 小工匠* @version 1.0* @mark: show me the code , change the world*/
public class CustomProducer {public static void main(String[] args) throws ExecutionException, InterruptedException {// 1. 创建kafka生产者的配置对象Properties properties = new Properties();// 2. 给kafka配置对象添加配置信息properties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.126.170:9092");// key,value序列化properties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());properties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());// 3. 创建kafka生产者对象KafkaProducer<String, String> kafkaProducer = new KafkaProducer<String, String>(properties);// 4. 调用send方法,发送消息for (int i = 0; i < 10; i++) {RecordMetadata art = kafkaProducer.send(new ProducerRecord<>("art", "kafka-msg-" + i)).get();System.out.println(art.offset());System.out.println("over - " + i);}// 5. 关闭资源kafkaProducer.close();}}

输出

31
over - 0
32
over - 1
33
over - 2
34
over - 3
35
over - 4
36
over - 5
37
over - 6
38
over - 7
39
over - 8
40
over - 9

忽略我这个offset … 我都发了好多次了…

看控制台的吧

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带回调函数的异步发送

回调函数callback（）会在producer收到ack时调用，为异步调用。

该方法有两个参数分别是RecordMetadata（元数据信息）和Exception（异常信息）。

• 如果Exception为null，说明消息发送成功，
• 如果Exception不为null，说明消息发送失败

带回调函数的异步发送流程

注意：消息发送失败会自动重试，不需要我们在回调函数中手动重试。

Code

package com.artisan.pc;import org.apache.kafka.clients.producer.*;
import org.apache.kafka.common.serialization.StringSerializer;import java.util.Properties;
import java.util.concurrent.ExecutionException;/*** @author 小工匠* @version 1.0* @mark: show me the code , change the world*/
public class CustomProducerWithCallBack {public static void main(String[] args) throws ExecutionException, InterruptedException {// 1. 创建kafka生产者的配置对象Properties properties = new Properties();// 2. 给kafka配置对象添加配置信息properties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.126.170:9092");// key,value序列化properties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());properties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());// 3. 创建kafka生产者对象KafkaProducer<String, String> kafkaProducer = new KafkaProducer<String, String>(properties);// 4. 调用send方法,发送消息for (int i = 0; i < 10; i++) {// 添加回调// 该方法在Producer收到ack时调用，为异步调用kafkaProducer.send(new ProducerRecord<>("art", "kafka-msg-callback-" + i), (recordMetadata, e) -> {// 没有异常,输出信息到控制台System.out.println("主题" + recordMetadata.topic() + ", 分区：" + recordMetadata.partition() + ", 偏移量：" + recordMetadata.offset());});}// 5. 关闭资源kafkaProducer.close();}}

控制台

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同步发送API

同步发送的意思就是，一条消息发送之后，会阻塞当前线程，直至返回ack。
由于send方法返回的是一个Future对象，根据Futrue对象的特点，我们也可以实现同步发送的效果，只需在调用Future对象的get方发即可。

package com.artisan.pc;import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.serialization.StringSerializer;import java.util.Properties;
import java.util.concurrent.ExecutionException;/*** @author 小工匠* @version 1.0* @mark: show me the code , change the world*/
public class CustomProducerSync {public static void main(String[] args) throws ExecutionException, InterruptedException {// 1. 创建kafka生产者的配置对象Properties properties = new Properties();// 2. 给kafka配置对象添加配置信息properties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.126.170:9092");// key,value序列化properties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());properties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());// 3. 创建kafka生产者对象KafkaProducer<String, String> kafkaProducer = new KafkaProducer<String, String>(properties);// 4. 调用send方法,发送消息for (int i = 0; i < 10; i++) {// 通过Future接口的get实现同步阻塞kafkaProducer.send(new ProducerRecord<>("art", "kafka-msg-get-" + i)).get() ;}// 5. 关闭资源kafkaProducer.close();}}