public class Heartbeat
{
    //Map统计总测量时间

    public static class CountMapper extends
        Mapper<Object, Text, Text, DoublePair>
    {
      
        private Text word = new Text();
        private DoublePair pair = new DoublePair();

        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());
                pair.setValue(1, 1);
                context.write(word, pair);
            }
        }
}

    //Reduce求平均心跳

    public static class CalulateReducer extends
        Reducer<Text, DoublePair, Text, DoublePair>
    {
               DoublePair pair = new DoublePair();
        Text text = new Text();

        public void reduce(Text key, Iterable<DoublePair> values,
                           Context context) throws IOException, InterruptedException
        {
            double count = 0;
            double sum = 0;

            System.out.print("key :" + key.toString());
            if(key.toString().equals("value"))
            {
                text.set("result");
                for (DoublePair val : values)
                {
                    sum += val.getvalue1();
                    count += val.getvalue2();
                }
                pair.setValue(sum, sum / count);//sum/count,即平均心跳
                context.write(text, pair);

            }
            else
            {
                for (DoublePair val : values)
                {
                    count += val.getvalue2();
                }

                sum = Double.valueOf(key.toString()) * count;
                text.set("value");
                pair.setValue(sum, count);
                context.write(text, pair);
            }
            System.out.println("\tcount: " + count + "\tsum: " + sum);

        }
    }

    public static void main(String[] args) throws Exception
    {
        Configuration conf = new Configuration();
        String[] otherArgs = new GenericOptionsParser(conf, args)
        .getRemainingArgs();
        if (otherArgs.length < 2)
        {
            System.err.println("Usage: wordcount <in> [<in>...] <out>");
            System.exit(2);
        }
        Job job = new Job(conf, "word count");//执行job

        job.setJarByClass(Heartbeat.class);
        job.setMapperClass(CountMapper.class);
        job.setCombinerClass(CalulateReducer.class);
        job.setReducerClass(CalulateReducer.class);

        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(DoublePair.class);

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(DoubleWritable.class);
        for (int i = 0; i < otherArgs.length - 1; ++i)
        {
            FileInputFormat.addInputPath(job, new Path(otherArgs[i]));//输出
        }
        FileOutputFormat.setOutputPath(job, new Path(
                                           otherArgs[otherArgs.length - 1]));
        job.waitForCompletion(true);

    }

    /**@author XingLiu
     * 自定义Writable类，这个类用来存放sum和count数对
     * */
    public static class DoublePair implements Writable
    {
        private double value1;
        private double value2;

        public DoublePair()
        {
        }

        public void setValue(double value1, double value2)
        {
            this.value1 = value1;
            this.value2 = value2;
        }

        public double getvalue1()
        {
            return value1;
        }

        public double getvalue2()
        {
            return value2;
        }

        public void readFields(DataInput in) throws IOException
        {
            // TODO Auto-generated method stub
            value1 = in.readDouble() + Double.MIN_VALUE;
            value2 = in.readDouble() + Double.MIN_VALUE;
        }

        public void write(DataOutput out) throws IOException
        {
            // TODO Auto-generated method stub
            out.writeDouble(value1 - Double.MIN_VALUE);
            out.writeDouble(value2 - Double.MIN_VALUE);
        }

        @Override
        public int hashCode()
        {
            return (int) (value1 * 157 + value2);
        }

        @Override
        public boolean equals(Object right)
        {
            if (right instanceof DoublePair)
            {
                DoublePair r = (DoublePair) right;
                return r.value1 == value1 && r.value2 == value2;
            }
            else
            {
                return false;
            }
        }
        public String toString()
        {
            return value1 + " " + value2;
        }
    }
}