kafka 消费者确认 代码

下面是使用 Java 语言编写的 Kafka 消费者确认代码示例：

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;
import org.apache.kafka.common.TopicPartition;

import java.util.Collections;
import java.util.Properties;

public class ConsumerWithManualCommit {
    public static void main(String[] args) {
        // 配置消费者属性
        Properties props = new Properties();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
        props.put(ConsumerConfig.GROUP_ID_CONFIG, "test-group");
        props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "false"); // 禁止自动提交位移
        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");

        KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);

        // 订阅主题
        consumer.subscribe(Collections.singletonList("test-topic"));

        try {
            while (true) {
                ConsumerRecords<String, String> records = consumer.poll(1000);
                for (ConsumerRecord<String, String> record : records) {
                    System.out.printf("topic = %s, partition = %d, offset = %d, key = %s, value = %s\n",
                            record.topic(), record.partition(), record.offset(), record.key(), record.value());

                    // 手动确认消息已经被消费
                    TopicPartition tp = new TopicPartition(record.topic(), record.partition());
                    consumer.commitSync(Collections.singletonMap(tp, new OffsetAndMetadata(record.offset() + 1)));
                }
            }
        } finally {
            consumer.close();
        }
    }
}

在上述代码中，设置了 `ENABLE_AUTO_COMMIT_CONFIG` 属性为 false，禁止自动提交位移。在消费消息的循环中，手动确认消息已经被消费，然后再提交位移。这样可以保证消息不会被重复消费，同时也可以避免消息丢失。