Java API获取consumer group最新提交位移的时间

碰到了有人问起这个问题，目前java consumer没有利用OffsetAndMetadata中的metadata字段记录提交的时间，故直接通过java consumer来查询是不行，我们需要直接读取__consumer_offsets，代码如下:

public static long lastCommitTimestamp(String groupName, String bootstrapServers) {
    int partition = Math.abs(groupName.hashCode() % 50); // Assume offset topic partition number is 50
    TopicPartition tp = new TopicPartition("__consumer_offsets", partition);

    Properties props = new Properties();
    props.put("bootstrap.servers", bootstrapServers);
    props.put("group.id", "test");
    props.put("enable.auto.commit", "false");
    props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
    props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
    try (KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props)) {
    	consumer.assign(Arrays.asList(tp));
    	consumer.poll(Duration.ZERO); // take effect

    	Map<TopicPartition, Long> endOffset = consumer.endOffsets(Collections.singletonList(tp));
    	consumer.seek(tp, endOffset.get(tp) - 1);

    	ConsumerRecords<String, String> records = consumer.poll(Duration.ofSeconds(30));
    	if (records.count() == 0) {
    		throw new IllegalStateException("Consumer group does not commit offsets.");
    	}
    	return records.iterator().next().timestamp();
    }
}