聊聊storm的stream的分流与合并

    @Test
    public void testStreamSplitJoin() throws InvalidTopologyException, AuthorizationException, AlreadyAliveException {
        TopologyBuilder builder = new TopologyBuilder();
​
        builder.setSpout("sentence-spout", new SentenceSpout());
        // SentenceSpout --> SplitStreamBolt
        builder.setBolt("split-bolt", new SplitStreamBolt())
                .shuffleGrouping("sentence-spout");
        // SplitStreamBolt split two stream --> WordCountBolt
        //NOTE 这里要指定上游的bolt以及要处理的streamId
        builder.setBolt("long-word-count-bolt", new CountStreamBolt(),5)
                .shuffleGrouping("split-bolt","longWordStream");
        builder.setBolt("short-word-count-bolt", new CountStreamBolt(),5)
                .shuffleGrouping("split-bolt","shortWordStream");
        // WordCountBolt join --> ReportBolt
        builder.setBolt("report-bolt", new ReportBolt())
                .shuffleGrouping("long-word-count-bolt")
                .shuffleGrouping("short-word-count-bolt");
​
        submitRemote(builder);
    }

public class SplitStreamBolt extends BaseRichBolt {
​
    private static final Logger LOGGER = LoggerFactory.getLogger(SplitStreamBolt.class);
​
    private OutputCollector collector;
​
    public void prepare(Map config, TopologyContext context, OutputCollector collector) {
        this.collector = collector;
    }
​
    //NOTE 这里要自己ack
    public void execute(Tuple tuple) {
        String sentence = tuple.getStringByField("sentence");
        String[] words = sentence.split(" ");
        for(String word : words){
            // NOTE 这里指定发送给指定streamId
            if(word.length() > 4){
                this.collector.emit("longWordStream",new Values(word));
            }else{
                this.collector.emit("shortWordStream",new Values(word));
            }
        }
        this.collector.ack(tuple);
    }
​
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declare(new Fields("word"));
        //NOTE 这里通过declareStream声明direct stream，并指定streamId
        declarer.declareStream("longWordStream",true,new Fields("word"));
        declarer.declareStream("shortWordStream",true,new Fields("word"));
    }
}

public class CountStreamBolt extends BaseBasicBolt{
​
    private static final Logger LOGGER = LoggerFactory.getLogger(CountStreamBolt.class);
​
    Map<String, Integer> longWordCounts = new HashMap<String, Integer>();
    Map<String, Integer> shortWordCounts = new HashMap<String, Integer>();
​
    @Override
    public void execute(Tuple input, BasicOutputCollector collector) {
        String sourceStreamId = input.getSourceStreamId();
​
        String word = input.getString(0);
​
        if(sourceStreamId.equals("longWordStream")){
            Integer count = longWordCounts.get(word);
            if (count == null) count = 0;
            count++;
            longWordCounts.put(word, count);
            LOGGER.info("long word:{} -> {}",word,count);
            collector.emit(new Values(word, count));
            return ;
        }
​
        if(sourceStreamId.equals("shortWordStream")){
            Integer count = shortWordCounts.get(word);
            if (count == null) count = 0;
            count++;
            shortWordCounts.put(word, count);
            LOGGER.info("short word:{} -> {}",word,count);
            collector.emit(new Values(word, count));
            return ;
        }
    }
​
    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declare(new Fields("word", "count"));
    }
}