Storm 从入门到精通 第十三讲 Stream Grouping-Custom Grouping

除了以上几种分组方式之外，我们还可以自己自定义分组，自己DIY去控制哪些Blot来接收Tuple；

实现自定义分组需要继承backtype.storm.grouping.CustomStreamGrouping 接口

我们现在业务中遇到一个问题想让用户的uid按照分段的规则grouping到对应的task上面，于是采用uid%k的方法将相同模值的记录在一个task进行业务处理，自己实现了ModStreamingGrouping，

代码如下：

package storm.starter;

import java.util.Arrays;
import java.util.List;
import java.util.Map;

import backtype.storm.grouping.CustomStreamGrouping;
import backtype.storm.task.TopologyContext;
import backtype.storm.tuple.Fields;

public class ModStreamGrouping implements CustomStreamGrouping {
  
  private Map _map;
  private TopologyContext _ctx;
  private Fields _fields;
  private List<Integer> _targetTasks;
  
  public ModStreamGrouping(){
     
  }
  
  @Override
  public void prepare(TopologyContext context, Fields outFields,
       List<Integer> targetTasks) {
     // TODO Auto-generated method stub
     _ctx = context;
     _fields = outFields;
     _targetTasks = targetTasks;
  }

  @Override
  public List<Integer> chooseTasks(List<Object> values) {
     // TODO Auto-generated method stub
     Long groupingKey = Long.valueOf( values.get(0).toString());
     int index = (int) (groupingKey%(_targetTasks.size()));
     return Arrays.asList(_targetTasks.get(index));
  }

}

测试：

package storm.starter;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Set;

import backtype.storm.Config;
import backtype.storm.LocalCluster;
import backtype.storm.spout.SpoutOutputCollector;
import backtype.storm.task.OutputCollector;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.TopologyBuilder;
import backtype.storm.topology.base.BaseRichBolt;
import backtype.storm.topology.base.BaseRichSpout;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.tuple.Values;
import backtype.storm.utils.Utils;

public class ModGroupingTest {
   public static class TestUidSpout extends BaseRichSpout {
       boolean _isDistributed;
       SpoutOutputCollector _collector;
           
       public void open(Map conf, TopologyContext context, SpoutOutputCollector collector) {
           _collector = collector;
       }
       
       public void close() {
           
       }
           
       public void nextTuple() {
           Utils.sleep(100);
          
           final Random rand = new Random();
           final int uid =rand.nextInt(100000000);
           
           _collector.emit(new Values(uid));
           
       }
       
       public void ack(Object msgId) {

       }

       public void fail(Object msgId) {
           
       }
       
       public void declareOutputFields(OutputFieldsDeclarer declarer) {
          declarer.declare(new Fields("uid"));
       }

   
   }
   
   public static class modGroupBolt extends BaseRichBolt {
        OutputCollector _collector;
        String _ComponentId;
        int _TaskId;
        @Override
        public void prepare(Map conf, TopologyContext context, OutputCollector collector) {

          _collector = collector;
          _ComponentId = context.getThisComponentId();
          _TaskId = context.getThisTaskId();
        }

        @Override
        public void execute(Tuple tuple) {
//            _collector.emit(tuple, new Values(tuple.getString(0) + "!!!"));
          System.out.println(_ComponentId+":"+_TaskId +"recevie :" + tuple.getInteger(0));
            
          _collector.emit(new Values(tuple));
            _collector.ack(tuple);
            
        }

        @Override
        public void declareOutputFields(OutputFieldsDeclarer declarer) {
            declarer.declare(new Fields("uid"));
        }


    }
   
   public static void main(String args[]){
       TopologyBuilder builder = new TopologyBuilder();
       builder.setSpout("uid", new TestUidSpout());
       builder.setBolt("process", new modGroupBolt(), 10).customGrouping("uid", new ModStreamGrouping());
       
       Config config = new Config();
       config.setDebug(true);
       
       config.setNumWorkers(3);
       LocalCluster cluster = new LocalCluster();
        cluster.submitTopology("test", config, builder.createTopology());
//        Utils.sleep(30000);
//        cluster.killTopology("test");
//        cluster.shutdown();    
   }
}