基本上你所做的只是字数统计，但与网址。
直接从教程中删除“psudeocode”。

class Mapper {

    final IntWritable ONE = new IntWritable(1);

    map(LongWritable key, Text value, Context context)  {
        String[] columns = value.split(" ");
        String url = columns[0];
        context.write(url, ONE);
    }  

}

class Reducer {

    IntWritable result = new IntWritable();

    reduce(Text key, Iterable<IntWritable> values, Context context) {
        int sum = sum(values);
        result.set(sum);
        context.write(key, result);
    }
}