以 WordCount 為例

自定義策略

/**
 * 自定義分組
 */
public class MyGrouping implements CustomStreamGrouping {

    //接受目標任務的id集合
    private List<Integer> targetTasks ;

    public void prepare(WorkerTopologyContext context, GlobalStreamId stream, List<Integer> targetTasks) {
        this.targetTasks = targetTasks ;
 

    }

    public List<Integer> chooseTasks(int taskId, List<Object> values) {
        List<Integer> subTaskIds = new ArrayList<Integer>();
        for(int i = 0 ; i <= targetTasks.size() / 2 ; i ++){
            subTaskIds.add(targetTasks.get(i));
        }
        return subTaskIds;
 

    }
}

源頭 Spout

public class WordCountSpout implements IRichSpout{
    private TopologyContext context ;
    private SpoutOutputCollector collector ;

    private List<String> states ;

    private Random r = new Random();

    private int index = 0;

    public void open(Map conf, TopologyContext context,
 
 SpoutOutputCollector collector) {
        this.context = context ;
        this.collector = collector ;
        states = new ArrayList<String>();
        states.add("hello world tom");
        states.add("hello world tomas");
        states.add("hello world tomasLee");
        states.add("hello world tomson");
    }

    public void close() {

    }

    public void activate() {

    }

    public void deactivate() {

    }

    public void nextTuple() {
        if(index < 3){
            String line = states.get(r.nextInt(4));
            collector.emit(new Values(line),index);
            index ++ ;
        }
    }

    public void ack(Object msgId) {
    }

    public void fail(Object msgId) {

    }

    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declare(new Fields("line"));
    }

    public Map<String, Object> getComponentConfiguration() {
        return null;
    }
}

分片 Bolt

public class SplitBolt implements IRichBolt {

    private TopologyContext context;
    private OutputCollector collector;

    public void prepare(Map stormConf, TopologyContext context, OutputCollector collector) {
        System.out.println(this + " : prepare()");
        this.context = context;
        this.collector = collector;
    }

    public void execute(Tuple tuple) {
        String line = tuple.getString(0);
        System.out.println(this + " : excute() : " + line);
        String[] arr = line.split(" ");
        for (String s : arr) {
            collector.emit(new Values(s, 1));
        }
    }

    public void cleanup() {

    }

    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declare(new Fields("word", "count"));

    }

    public Map<String, Object> getComponentConfiguration() {
        return null;
    }
}

WCApp

public class WCApp {
    public static void main(String[] args) throws Exception {
        TopologyBuilder builder = new TopologyBuilder();
        //設定Spout
        builder.setSpout("wcspout", new WordCountSpout()).setNumTasks(2);
        //設定creator-Bolt
        builder.setBolt("split-bolt", new SplitBolt(), 4).customGrouping("wcspout", new MyGrouping()).setNumTasks(4);

        Config conf = new Config();
        conf.setNumWorkers(2);
        conf.setDebug(true);

        /**
         * 本地模式storm
         */
        LocalCluster cluster = new LocalCluster();
        cluster.submitTopology("wc", conf, builder.createTopology());
        System.out.println("hello world");
    }
}