storm（三） 编程关键类

Storm概念

• storm的编程其实就是设计topology的过程，该过程中最主要的就是Spout、bolt还有grouping

关键类

创建topology

• 这个部分可以直接参考官网，使用TopologyBuilder类

TopologyBuilder builder = new TopologyBuilder();
builder.setSpout("createNum",new NumSpout(),1);
builder.setBolt("countNum",new SumBolt(),1)
        .shuffleGrouping("createNum");
StormTopology topology=builder.createTopology();

Spout和Bolt

spout

• BaseRichSpout（帮我们将一些不用关注的方法空实现了）
  
  • BaseComponent
    
    • IComponent
  • IRichSpout（主要需要实现的方法都在这里面）
    
    • ISpout
    • IComponent
• 现在BaseRichSpout中还需要实现的就是：

public class ReadSpout extends BaseRichSpout {
    private SpoutOutputCollector collector;
    private final static String FILE_DIR="testFile.txt";
    private final static String SEPARATOR=",";
    public void open(Map conf, TopologyContext context, SpoutOutputCollector collector) {
        this.collector=collector;
    }
    public void nextTuple() {
        File file=new File(FILE_DIR);
        try (
            BufferedReader br=new BufferedReader(new FileReader(file));
        ){
            String line;
            while ((line=br.readLine())!=null) {
                collector.emit(new Values(line));
                System.out.println("line:" + line);
            }
            Thread.sleep(10000);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declare(new Fields("line"));
    }
}

bolt

• BaseRichBolt
  
  • BaseComponent
    
    • IComponent
  • IRichBolt（主要需要实现的方法都在这里面）
    
    • ISpout
    • IComponent

public class SplitBolt extends BaseRichBolt {
    private OutputCollector collector;
    private final static String SEPARATOR=",";
    @Override
    public void prepare(Map stormConf, TopologyContext context, OutputCollector collector) {
        this.collector=collector;
    }
    @Override
    public void execute(Tuple input) {
        String line=input.getStringByField("line");
        String[] words=line.split(SEPARATOR);
        for (String word:words){
            this.collector.emit(new Values(word));
        }
        System.out.println("word:"+ Arrays.toString(words));
    }
    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declare(new Fields("word"));
    }
}