examples/storm-redis-examples/src/main/java/org/apache/storm/redis/topology/WordCounter.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.storm.redis.topology;

import com.google.common.collect.Maps;

import java.util.Map;

import org.apache.storm.task.TopologyContext;
import org.apache.storm.topology.BasicOutputCollector;
import org.apache.storm.topology.IBasicBolt;
import org.apache.storm.topology.OutputFieldsDeclarer;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Tuple;
import org.apache.storm.tuple.Values;

public class WordCounter implements IBasicBolt {
    private Map<String, Integer> wordCounter = Maps.newHashMap();

    @Override
    public void prepare(Map<String, Object> topoConf, TopologyContext context) {
    }

    @Override
    public void execute(Tuple input, BasicOutputCollector collector) {
        String word = input.getStringByField("word");
        int count;
        if (wordCounter.containsKey(word)) {
            count = wordCounter.get(word) + 1;
            wordCounter.put(word, wordCounter.get(word) + 1);
        } else {
            count = 1;
        }

        wordCounter.put(word, count);
        collector.emit(new Values(word, String.valueOf(count)));
    }

    @Override
    public void cleanup() {

    }

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

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

}