Java实现单词计数MapReduce

单词计数：Hadoop Word Count

实现代码：

import java.util.*;

/**
 * 单词计数
 */
public class WordCount {

    private interface OutputCollector<K, V> {
        void collect(K key, V value);
    }

    public static class Map {
        public void map(String key, String value, OutputCollector<String, Integer> output) {
            StringTokenizer tokenizer = new StringTokenizer(value);
            while (tokenizer.hasMoreTokens()) {
                String word = tokenizer.nextToken();
                output.collect(word, 1);
            }
        }
    }

    public static class Reduce {
        public void reduce(String key, Iterator<Integer> values, OutputCollector<String, Integer> output) {
            int sum = 0;
            while (values.hasNext()) {
                sum += values.next();
            }
            output.collect(key, sum);
        }
    }

}