MapReduce排序分类（一）

public class InternalSort {
    public static class Map extends Mapper<LongWritable, Text, IntWritable, Text> {
        private IntWritable score = new IntWritable();
        private Text name = new Text();
        
        public void map(LongWritable key, Text value, Context context) 
            throws IOException, InterruptedException {
            String[] parts = value.toString().split(",");
            name.set(parts[0]);
            score.set(Integer.parseInt(parts[1]));
            context.write(score, name);
        }
    }
    
    public static class Reduce extends Reducer<IntWritable, Text, Text, IntWritable> {
        public void reduce(IntWritable key, Iterable<Text> values, Context context) 
            throws IOException, InterruptedException {
            for (Text value : values) {
                context.write(value, key);
            }
        }
    }
    
    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        Job job = new Job(conf, "InternalSort");
        job.setJarByClass(InternalSort.class);
        job.setMapperClass(Map.class);
        job.setReducerClass(Reduce.class);
        job.setOutputKeyClass(IntWritable.class);
        job.setOutputValueClass(Text.class);
        job.setSortComparatorClass(IntWritable.Comparator.class);
        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}