mapreduce 中单表关联的问题

public class STjoin {

    public static int time = 0;

    public static class Map extends Mapper<Object,Text,Text,Text>{

        public void map(Object key,Text value,Context context)throws IOException,InterruptedException{

            String childnName = new String();

            String parentName = new String();

            //String relationtype = new String();

            String line = value.toString();

            String[] strs= line.split("	");



            context.write(new Text(strs[1]),new Text("1"+"-"+strs[0]));//输出左表

            context.write(new Text(strs[0]),new Text("2"+"-"+strs[1]));//输出右表

        }

    }



    public static class Reduce extends Reducer<Text,Text,Text,Text>{

        public void reduce(Text key,Iterable<Text> values,Context context)throws IOException,InterruptedException{

            if (time == 0){//输出表头

                context.write(new Text("grandchild"),new Text("grandparent"));

                time++;

            }

            int grandchildNum = 0;

            String grandchild[] = new String[20];

            int grandparentNum = 0;

            String grandparent[] = new String[20];



            Iterator iter = values.iterator();

            while (iter.hasNext()){

                String record = iter.next().toString();

                String[] st = record.split("-");

                if(st[0].equals("1")){

                    grandchild[grandchildNum]  =st[1];

                    grandchildNum ++;



                } else if(st[0].equals("2")){

                    grandparent [grandparentNum ]=st[1];

                    grandparentNum ++;

                }

            }





            //grandchild和grandparent数组求笛卡尔积

            if(grandchildNum !=0 && grandparentNum !=0){

                for (int m=0;m<grandchildNum;m++){

                    for (int n=0;n<grandparentNum;n++){

                        context.write(new Text(grandchild[m]),new Text(grandparent[n]));

                    }

                }



            }



        }



    }





    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:...");

            System.exit(2);

        }

        Job job = new Job(conf,"single table join");

        job.setJarByClass(STjoin.class);

        job.setMapperClass(Map.class);

        job.setCombinerClass(Reduce.class);

        job.setReducerClass(Reduce.class);



        job.setOutputKeyClass(Text.class);

        job.setOutputValueClass(Text.class);



        FileInputFormat.addInputPath(job,new Path(otherArgs[0]));

        FileOutputFormat.setOutputPath(job,new Path(otherArgs[1]));

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

    }

}