ParseTweetBolt.java

package udacity.storm;

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

import java.util.Map;

/**
 * A bolt that parses the tweet into words
 */
public class ParseTweetBolt extends BaseRichBolt 
{
  // To output tuples from this bolt to the count bolt
  OutputCollector collector;

  @Override
  public void prepare(
      Map                     map,
      TopologyContext         topologyContext,
      OutputCollector         outputCollector) 
  {
    // save the output collector for emitting tuples
    collector = outputCollector;
  }

  @Override
  public void execute(Tuple tuple) 
  {
    // get the 1st column 'tweet' from tuple
    String tweet = tuple.getString(0);

    // provide the delimiters for splitting the tweet
    String delims = "[ .,?!]+";

    // now split the tweet into tokens
    String[] tokens = tweet.split(delims);

    // for each token/word, emit it
    for (String token: tokens) {
      collector.emit(new Values(token));
    }
  }

  @Override
  public void declareOutputFields(OutputFieldsDeclarer declarer) 
  {
    // tell storm the schema of the output tuple for this spout
    // tuple consists of a single column called 'tweet-word'
    declarer.declare(new Fields("tweet-word"));
  }
}