kafak推送消息。

1、引入依赖

maven

<dependency>  
    <groupId>org.springframework.kafkagroupId>  
    <artifactId>spring-kafkaartifactId>  
    <version>2.8.0version>  
dependency>

gradle

dependencies {
    compile "org.springframework.kafka:spring-kafka
}

2、添加配置

在application.properties或application.yml中配置Kafka

spring:  
  kafka:  
    bootstrap-servers: localhost:9092 # Kafka集群的地址，格式为host:port，多个地址用逗号分隔  
    consumer:  
      group-id: myGroup # 消费者群组ID，用于标识一组消费者实例  
      auto-offset-reset: earliest # 当Kafka中没有初始偏移量或当前偏移量不再存在时（例如，数据被删除），从何处开始读取：earliest表示从最早的记录开始，latest表示从最新的记录开始  
      key-deserializer: org.apache.kafka.common.serialization.StringDeserializer # 键的反序列化器，用于将字节转换为Java对象  
      value-deserializer: org.apache.kafka.common.serialization.StringDeserializer # 值的反序列化器，用于将字节转换为Java对象  
    producer:  
      key-serializer: org.apache.kafka.common.serialization.StringSerializer # 键的序列化器，用于将Java对象转换为字节  
      value-serializer: org.apache.kafka.common.serialization.StringSerializer # 值的序列化器，用于将Java对象转换为字节

3、代码

1、方法

异步调用

import org.springframework.beans.factory.annotation.Autowired;  
import org.springframework.kafka.core.KafkaTemplate;  
import org.springframework.kafka.support.SendResult;  
import org.springframework.util.concurrent.ListenableFuture;  
import org.springframework.util.concurrent.ListenableFutureCallback;  
  
public class KafkaMessageSender {  
  
    @Autowired  
    private KafkaTemplate<String, String> kafkaTemplate;  
  
    public void sendMessage(String topic, String message) {  
        // 同步发送消息并等待响应  
        ListenableFuture<SendResult<String, String>> future = kafkaTemplate.send(topic, message);  
        try {  
            SendResult<String, String> result = future.get(); // 阻塞等待发送结果  
            System.out.println("Sent message=[" + message + "] with topic=[" + topic + "]");  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
    }  
  
    public void sendMessageWithCallback(String topic, String message) {  
        // 异步发送消息并注册回调  
        ListenableFuture<SendResult<String, String>> future = kafkaTemplate.send(topic, message);  
        future.addCallback(new ListenableFutureCallback<SendResult<String, String>>() {  
            @Override  
            public void onSuccess(SendResult<String, String> result) {  
                System.out.println("Sent message=[" + message + "] with topic=[" + topic + "]");  
            }  
  
            @Override  
            public void onFailure(Throwable ex) {  
                System.err.println("Failed to send message=[" + message + "] with topic=[" + topic + "]: " + ex.getMessage());  
            }  
        });  
    }  
  
    // 其他方法...  
}

调用方法

public class SomeService {  
  
    @Autowired  
    private KafkaMessageSender kafkaMessageSender;  
  
    public void someMethod() {  
        String topic = "some-topic";  
        String message = "Hello, Kafka!";  
        kafkaMessageSender.sendMessageWithCallback(topic, message);  
    }  
}

同步调用

import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Service;

@Service
public class MessageProducer {

    private final KafkaTemplate<String, String> kafkaTemplate;

    public MessageProducer(KafkaTemplate<String, String> kafkaTemplate) {
        this.kafkaTemplate = kafkaTemplate;
    }

    public void sendMessage(String topic, String message) {
        try {
            kafkaTemplate.send(topic, message).get();
            System.out.println("Message sent successfully.");
        } catch (InterruptedException | ExecutionException e) {
            System.err.println("Failed to send message: " + e.getMessage());
            Thread.currentThread().interrupt();
        }
    }
}

2、send

1、发送简单的消息

ListenableFuture<SendResult<String, String>> future = kafkaTemplate.send(topic, message);

2、发送带有键的消息

ListenableFuture<SendResult<String, String>> future = kafkaTemplate.send(topic, key, message);

3、发送带有分区号的消息
``java
ListenableFuture> future = kafkaTemplate.send(topic, partition, key, message);

4、发送带有时间戳的消息
```java
ListenableFuture> future = kafkaTemplate.send(topic, partition, key, message, timestamp);

5、发送带有自定义头信息的消息

Map<String, Object> headers = new HashMap<>();  
headers.put("myHeaderKey", "myHeaderValue");  
ListenableFuture<SendResult<String, String>> future = kafkaTemplate.send(topic, partition, key, message, timestamp, headers);

6、使用ProducerRecord发送消息

ProducerRecord<String, String> record = new ProducerRecord<>(topic, key, message);  
ListenableFuture<SendResult<String, String>> future = kafkaTemplate.send(record);

7、使用Message发送消息（Spring Kafka 2.2及更高版本）

Message<String> message = MessageBuilder.withPayload(payload).setHeader(KafkaHeaders.TOPIC, topic).build();  
ListenableFuture<SendResult<String, String>> future = kafkaTemplate.send(message);