Java kafka 如何等待消息消费完再执行下面逻辑

您可以在 Java 代码中使用 Kafka Consumer API 的 poll() 方法，该方法会等待消息消费完成后再继续执行后面的逻辑。

代码示例如下：

KafkaConsumer<String, String> consumer = ...;
while (true) {
    ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
    for (ConsumerRecord<String, String> record : records) {
        // process the record
    }
    // manually commit the offsets if the processing was successful
    consumer.commitSync();
}

在这个示例中，consumer.poll(Duration.ofMillis(100)) 方法会等待 100 毫秒，如果在这段时间内没有消息到达，则继续执行下面的逻辑。当消息到达时，它会将消息读取到 ConsumerRecords 对象中，然后您可以使用 for 循环进行处理。在处理完成后，您可以使用 consumer.commitSync() 方法手动提交偏移量。

相关问题

kafka消费时，新建线程池java示例

可以参考下面的Java代码示例来实现Kafka消费时的线程池：

import java.util.Properties;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;

public class KafkaConsumerThreadPoolExample {
    private final KafkaConsumer<String, String> consumer;
    private final String topic;
    private ExecutorService executor;
 
    public KafkaConsumerThreadPoolExample(String brokers, String groupId, String topic) {
        Properties prop = createConsumerConfig(brokers, groupId);
        this.consumer = new KafkaConsumer<String, String>(prop);
        this.topic = topic;
    }
 
    public void shutdown() {
        if (consumer != null) {
            consumer.close();
        }
        if (executor != null) {
            executor.shutdown();
        }
    }
 
    public void run(int numThreads) {
        executor = Executors.newFixedThreadPool(numThreads);
 
        List<Runnable> tasks = new ArrayList<Runnable>();
        for (int i = 0; i < numThreads; i++) {
            tasks.add(new KafkaConsumerThread(consumer, topic));
        }
 
        for (Runnable task : tasks) {
            executor.submit(task);
        }
    }
 
    private static Properties createConsumerConfig(String brokers, String groupId) {
        Properties props = new Properties();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, brokers);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
        props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "true");
        props.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, "1000");
        props.put(ConsumerConfig.SESSION_TIMEOUT_MS_CONFIG, "30000");
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
        return props;
    }
 
    public static void main(String[] args) {
        String brokers = "localhost:9092";
        String groupId = "test-group";
        String topic = "test-topic";
        int numThreads = 4;
 
        KafkaConsumerThreadPoolExample example = new KafkaConsumerThreadPoolExample(brokers, groupId, topic);
        example.run(numThreads);
    }
}
 
class KafkaConsumerThread implements Runnable {
    private final KafkaConsumer<String, String> consumer;
    private final String topic;
 
    public KafkaConsumerThread(KafkaConsumer<String, String> consumer, String topic) {
        this.consumer = consumer;
        this.topic = topic;
    }
 
    public void run() {
        consumer.subscribe(Arrays.asList(this.topic));
 
        while (true) {
            ConsumerRecords<String, String> records = consumer.poll(1000);
            for (ConsumerRecord<String, String> record : records) {
                System.out.println(Thread.currentThread().getName() + " : " + record.value());
            }
        }
    }
}

以上代码示例中，KafkaConsumerThreadPoolExample类是一个简单的Kafka消费者线程池实现，其中run方法启动了numThreads个线程，每个线程都创建了一个KafkaConsumerThread对象，并调用executor.submit(task)方法提交到线程池中执行。KafkaConsumerThread类是一个简单的消费者线程实现，其中run方法中的代码是从Kafka主题中读取消息并处理的逻辑。

一个消费kafka数据的线程池，java实现类

以下是一个使用Java实现的简单Kafka消费者线程池示例：

import java.util.Arrays;
import java.util.Properties;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
 
public class KafkaConsumerThreadPool {
 
    private final KafkaConsumer<String, String> consumer;
    private final String topic;
    private ExecutorService executor;
 
    public KafkaConsumerThreadPool(String brokers, String groupId, String topic) {
        Properties prop = createConsumerConfig(brokers, groupId);
        this.consumer = new KafkaConsumer<>(prop);
        this.topic = topic;
    }
 
    public void shutdown() {
        if (consumer != null) {
            consumer.close();
        }
        if (executor != null) {
            executor.shutdown();
        }
    }
 
    public void run(int numThreads) {
        executor = Executors.newFixedThreadPool(numThreads);
 
        for (int i = 0; i < numThreads; i++) {
            executor.submit(new KafkaConsumerThread(consumer, topic));
        }
    }
 
    private static Properties createConsumerConfig(String brokers, String groupId) {
        Properties props = new Properties();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, brokers);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
        props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "true");
        props.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, "1000");
        props.put(ConsumerConfig.SESSION_TIMEOUT_MS_CONFIG, "30000");
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
        return props;
    }
 
    public static void main(String[] args) {
        String brokers = "localhost:9092";
        String groupId = "test-group";
        String topic = "test-topic";
        int numThreads = 4;
 
        KafkaConsumerThreadPool example = new KafkaConsumerThreadPool(brokers, groupId, topic);
        example.run(numThreads);
    }
}
 
class KafkaConsumerThread implements Runnable {
    private final KafkaConsumer<String, String> consumer;
    private final String topic;
 
    public KafkaConsumerThread(KafkaConsumer<String, String> consumer, String topic) {
        this.consumer = consumer;
        this.topic = topic;
    }
 
    public void run() {
        consumer.subscribe(Arrays.asList(this.topic));
 
        while (true) {
            ConsumerRecords<String, String> records = consumer.poll(100);
            for (ConsumerRecord<String, String> record : records) {
                System.out.println(Thread.currentThread().getName() + " : " + record.value());
            }
        }
    }
}

在上面的代码示例中，KafkaConsumerThreadPool类是一个简单的Kafka消费者线程池实现，其中run方法启动了numThreads个线程，每个线程都创建了一个KafkaConsumerThread对象，并调用executor.submit(task)方法提交到线程池中执行。KafkaConsumerThread类是一个简单的消费者线程实现，其中run方法中的代码是从Kafka主题中读取消息并处理的逻辑。