我正在努力学习mapreduce。从mapreduce wordcount中所示的wordcount示例开始，当我在eclipse中执行代码时，它的输出是正确的word count。i/p文件内容如下follows:-
你好世界再见世界
它的输出是
再见1
你好1
世界2
之后，我通过在输入文件中的每个单词后面用逗号替换空格来测试代码。
现在我已经将输入恢复到与以前相同的状态，但是现在输出中的字数是预期结果的两倍。
再见2
你好2
世界4
我的代码如下：

public static class TokenizerMapper extends Mapper<Object, Text, Text,IntWritable>{
    public static IntWritable one = new IntWritable(1);
    private Text word = new Text();
    public void map(Object key, Text value, Context context) throws IOException, InterruptedException{
        StringTokenizer itr = new StringTokenizer(value.toString());
        while (itr.hasMoreTokens()){
            word.set(itr.nextToken());
            context.write(word, one);
        }
    }
}

public static class IntSumReducer extends Reducer<Text, IntWritable, Text, IntWritable>{
    private IntWritable result = new IntWritable();
    public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException{
        int sum=0;
        for(IntWritable val:values){
            sum +=val.get();
        }
        result.set(sum);
        context.write(key, result);
    }
}

public static void main(String[] str) throws Exception{
    Configuration conf = new Configuration();
    Job job = Job.getInstance(conf, "word count");

    job.setJarByClass(WordCount.class);
    job.setMapperClass(TokenizerMapper.class);
    job.setCombinerClass(IntSumReducer.class);
    job.setReducerClass(IntSumReducer.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(IntWritable.class);

   FileInputFormat.addInputPath(job, new Path(str[0]));
   FileOutputFormat.setOutputPath(job,new Path(str[1]));

   System.exit(job.waitForCompletion(true) ? 0 : 1);

}

有人能解释一下reducer方法中每个词的值是如何分组的，因为它对特定词的每个值进行求和，检查同一个词是否有两个计数。
谢谢