这个是在window环境下面安装的kafka

• 下载pom依赖

编写代码

• 编写SplitSentenceBolt
  public class SplitSentenceBolt extends BaseRichBolt {
  private OutputCollector collector;

  @Override
  public void prepare(Map map, TopologyContext topologyContext, OutputCollector outputCollector) {
      this.collector=outputCollector;
  }
  @Override
  public void execute(Tuple tuple) {
      //String sentece = tuple.getStringByField("sentence");
      String sentece=tuple.getString(4);
      String[] words = sentece.split(" ");
      for (String word:words){
          collector.emit(new Values(word));
      }
  }
  @Override
  public void declareOutputFields(OutputFieldsDeclarer outputFieldsDeclarer) {
      outputFieldsDeclarer.declare(new Fields("words"));
  }

  }

• 编写WordCountBolt
  public class WordCountBolt extends BaseRichBolt {

  private  OutputCollector collector;
  private HashMap<String,Long> counts =null;
  @Override
  public void prepare(Map map, TopologyContext topologyContext, OutputCollector outputCollector) {
      this.collector = outputCollector;
      this.counts = new HashMap<>();
  }
  @Override
  public void execute(Tuple tuple) {
       String word = tuple.getStringByField("words");
      // String word =tuple.getString(0);
      Long count=this.counts.get(word);
      if(count==null){
          count=0L;
      }
      count++;
      //出现就添加到map中,word相同的,会覆盖掉 所以最后的word就是准确的数据
      this.counts.put(word,count);
      this.collector.emit(new Values(word,count));
  }
  @Override
  public void declareOutputFields(OutputFieldsDeclarer outputFieldsDeclarer) {
          outputFieldsDeclarer.declare(new Fields("word","count"));
  }

  }

• 编写ReportBolt
  public class ReportBolt extends BaseRichBolt {
  private HashMap

  @Override
  public void execute(Tuple input) {
      String word=input.getStringByField("word");
      Long count=input.getLongByField("count");
      this.counts.put(word, count);
      System.out.println("--------FINAL COUNTS--------");
      List<String> keys=new ArrayList<String>();
      keys.addAll(this.counts.keySet());
      Collections.sort(keys);
      for(String key:keys){
          System.out.println(key+":"+this.counts.get(key));
      }
      System.out.println("----------------------------");
  }
  @Override
  public void declareOutputFields(OutputFieldsDeclarer outputFieldsDeclarer) {
  }

  }

• 编写Topology
  public class MainTopology {
  public static void main(String[] args)throws Exception {
  TopologyBuilder builder = new TopologyBuilder();
  KafkaSpoutConfig.Builder

      //设置kafka属于哪个组
      kafkabuilder.setGroupId("testgroup");
      //创建kafkaspoutConfig
      KafkaSpoutConfig<String, String> build = kafkabuilder.build();
      //通过kafkaspoutconfig获取kafkaspout
      KafkaSpout<String, String> kafkaSpout = new KafkaSpout<>(build);
      //设置四个线程接收数据
      builder.setSpout("kafkaspout",kafkaSpout,4);

  // builder.setBolt(“printBolt”, new PrintBolt(),2).localOrShuffleGrouping(“kafkaspout”);

      builder.setBolt("split-bolt",new SplitSentenceBolt(),2).setNumTasks(4).shuffleGrouping("kafkaspout");
      // 有时候我们需要将特定数据的tuple路由到特殊的bolt实例中,在此我们使用fieldsGrouping
      // 来保证所有"word"字段值相同的tuple会被路由到同一个WordCountBolt实例中
      builder.setBolt("count-bolt",new WordCountBolt(),2).fieldsGrouping("split-bolt",new Fields("words"));
      builder.setBolt("report-bolt",new ReportBolt()).globalGrouping("count-bolt");
      Config config=new Config();
      config.setDebug(false);
      config.setNumWorkers(2);
      LocalCluster cluster =new LocalCluster();
      cluster.submitTopology("kafkaspout",config,builder.createTopology());
  }