1、kafkaTemplate.send()方法

1.1、springboot集成kafka发送消息Message对象消息

生产者代码

package com.power.producer;

import org.springframework.kafka.annotation.KafkaHandler;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.kafka.support.KafkaHeaders;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;

@Component
public class EventProducer {

    @Resource
    private KafkaTemplate<String,String> kafkaTemplate;

    public void sendMessage(){
        //通过构建器模式创建Message对象
        Message message = MessageBuilder.withPayload("hello-message")
                .setHeader(KafkaHeaders.TOPIC,"test-topic-02")//在header中放置topic的名字
                .build();
        kafkaTemplate.send(message);
    }
}

2、测试类

package com.power;

import com.power.producer.EventProducer;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;

import javax.annotation.Resource;

@SpringBootTest
public class SpringBoot01KafkaBaseApplication {

    @Resource
    private EventProducer eventProducer;
    
    @Test
    void testMessage(){
        eventProducer.sendMessage();
    }
    
	@Test
	void testMessage(){
	    eventProducer.sendMessage();
	}
}

1.2、springboot集成kafka发送ProducerRecord对象消息

生产者

package com.power.producer;

import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.header.Headers;
import org.apache.kafka.common.header.internals.RecordHeaders;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.kafka.support.KafkaHeaders;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.nio.charset.StandardCharsets;

@Component
public class EventProducer {

    @Resource
    private KafkaTemplate<String,String> kafkaTemplate;

    public void sendMessage(){
        //通过构建器模式创建Message对象
        Message message = MessageBuilder.withPayload("hello-message")
                .setHeader(KafkaHeaders.TOPIC,"test-topic-02")//在header中放置topic的名字
                .build();
        kafkaTemplate.send(message);
    }

    public void sendProducerRecord(){
        //Headers里面放一些信息（信息是key-value键值对），到时候消费组接收到消息后，可以拿到这个Headers里面放的信息
        Headers headers = new RecordHeaders();
        headers.add("phone","17676767676".getBytes(StandardCharsets.UTF_8));
        headers.add("orderId","OD1456467576467".getBytes(StandardCharsets.UTF_8));
        //String topic, Integer partition, Long timestamp, K key, V value, Iterable<Header> headers
        ProducerRecord<String,String> record =
                new ProducerRecord("test-topic-02", 0, System.currentTimeMillis(), "key1", "value", headers);
        kafkaTemplate.send(record);
    }
}

测试类：

package com.power;

import com.power.producer.EventProducer;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;

import javax.annotation.Resource;

@SpringBootTest
public class SpringBoot01KafkaBaseApplication {

    @Resource
    private EventProducer eventProducer;

    @Test
    void testProducerRecord(){
        eventProducer.sendProducerRecord();
    }

}

1.3、springboot集成kafka发送指定分区消息

生产者：（方法sendEvent4）

package com.power.producer;

import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.header.Headers;
import org.apache.kafka.common.header.internals.RecordHeaders;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.kafka.support.KafkaHeaders;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.nio.charset.StandardCharsets;

@Component
public class EventProducer {

    @Resource
    private KafkaTemplate<String,String> kafkaTemplate;

    public void sendEvent4(){
        //String topic, Integer partition, Long timestamp, K key, V data
        kafkaTemplate.send("test-topic-02",0,System.currentTimeMillis(),"k2","hello-kafka");
    }
}

测试类：

package com.power;

import com.power.producer.EventProducer;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;

import javax.annotation.Resource;

@SpringBootTest
public class SpringBoot01KafkaBaseApplication {

    @Resource
    private EventProducer eventProducer;

    @Test
    void sendEvent4(){
        eventProducer.sendEvent4();
    }
}

2、kafkaTemplate.sendDefault()方法

生产者：

package com.power.producer;

import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.header.Headers;
import org.apache.kafka.common.header.internals.RecordHeaders;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.kafka.support.KafkaHeaders;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.nio.charset.StandardCharsets;

@Component
public class EventProducer {

    @Resource
    private KafkaTemplate<String,String> kafkaTemplate;
    
    public void sendDefault(){
        //Integer partition, Long timestamp, K key, V data
        kafkaTemplate.sendDefault(0,System.currentTimeMillis(),"k3","hello-kafka");
    }
}

测试类：

package com.power;

import com.power.producer.EventProducer;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;

import javax.annotation.Resource;

@SpringBootTest
public class SpringBoot01KafkaBaseApplication {

    @Resource
    private EventProducer eventProducer;

    @Test
    void sendDefault(){
        eventProducer.sendDefault();
    }
}

配置文件：设置默认topic
不设置topic运行生产者会报找不到topic的错。

3、kafkaTemplate.send(…)和kafkaTemplate.sendDefault(…)的区别