创建Storm Spout
功能介绍
Spout是Storm的消息源,它是Topology的消息生产者,一般来说消息源会从一个外部源读取数据并向Topology中发送消息(Tuple)。
一个消息源可以发送多条消息流Stream,可以使用OutputFieldsDeclarer.declarerStream来定义多个Stream,然后使用SpoutOutputCollector来发射指定的Stream。
代码样例
下面代码片段在com.huawei.storm.example.common.RandomSentenceSpout类中,作用在于将收到的字符串拆分成单词。
/** * {@inheritDoc} */ @Override public void nextTuple() { Utils.sleep(100); String[] sentences = new String[] {"the cow jumped over the moon", "an apple a day keeps the doctor away", "four score and seven years ago", "snow white and the seven dwarfs", "i am at two with nature"}; String sentence = sentences[random.nextInt(sentences.length)]; collector.emit(new Values(sentence)); }