wordcount加排序

public class WordCount {

    public static class WordCountMap extends Mapper {
        @Override
        protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
            String[] words = value.toString().split(" ");
            for (String word : words) {
                // 把这个单词转换成键值对
                // 键：单词，值：1
                // context.write方法，会把键值对包装好写出，给到reduce端
                context.write(new Text(word), new IntWritable(1));
            }
        }
    }

    public static class WordCountReduce extends Reducer{
        PriorityQueue queue =new PriorityQueue();
        @Override
        protected void reduce(Text key, Iterable values, Context context) throws IOException, InterruptedException {
            int sum = 0;
            for (IntWritable value : values) {
                sum += value.get();
            }
            Item item = new Item(key.toString(), (long) sum);
            if (queue.size()<=10 || queue.peek().getCount()10){
                queue.poll();
            }
        }
        @Override
        protected void cleanup(Context context) throws IOException, InterruptedException {
            for (Item item :queue ) {
                context.write(new Text(item.getWord()),new IntWritable(Math.toIntExact(item.getCount())));
            }
        }
    }

    public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf, "word count");
        job.setJarByClass(WordCount.class);
        job.setMapperClass(WordCountMap.class);
        job.setReducerClass(WordCountReduce.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        FileInputFormat.addInputPath(job, new Path("input"));
        FileOutputFormat.setOutputPath(job, new Path("output"));
        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }

}

public class Item implements Serializable,Comparable {
    private String word;
    private Long count;

    public Item(String word, Long count) {
        this.word = word;
        this.count = count;
    }

    public String getWord() {
        return word;
    }

    public void setWord(String word) {
        this.word = word;
    }

    public Long getCount() {
        return count;
    }

    public void setCount(Long count) {
        this.count = count;
    }


    @Override
    public int compareTo(Item o) {
        return Long.compare(count,o.getCount());
    }
}