Kafka之consumer

1 pause

2 resume

3 wakeup 会抛出异常，正好可以退出循环

4 auto.offset.reset = latest,earlist,none none当没有消费记录时 抛出异常

5 seek 指定offset 在使用seek之前要先使用poll保证该consumer能够被分配某一个partition，然后才能够执行seek。也可以执行assignment

6  endOffsets 注意该方法返回的是即将写入的位点，而不是最后的那个数据的位点。beginningOffset,同时还有seekToEnd seekToBeginning

7  public Map<TopicPartition, OffsetAndTimestamp> offsetsForTimes(Map<TopicPartition, Long> timestampsToSearch) 

Map<TopicPartition , Long> timestampToSearch = new HashMap<>() ;
for (TopicPartition tp : assignment ) {
    timestampToSearch.put(tp , System.currentTimeMillis() - 1*24*3600*1000);
Map<TopicPartition , OffsetAndTimestamp> offsets = consumer.offsetsForTimes(timestampToSearch) ;
for (TopicPartition tp : assignment) {
    OffsetAndTimestamp offsetAndTimestamp = offsets.get(tp) ;
if (offsetAndTimestamp ! = null) {
    consumer.seek (tp, off setAndTimestamp.offset() 
    };

8 想退出consumer的poll，最好最安全的做法就是通过另外的线程调用wakeup，抛出异常是捕获，同时在finally中close

9 指定想消费的某一个partition 可以这么写 

Set<TopicPartition> topicPartitionSet = new HashSet<>();
topicPartitionSet.add(new TopicPartition(topic,0));
consumer.assign(topicPartitionSet);