Q3DeptEarliestEmp.java

package com.elon33.mr1;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.net.URI;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.filecache.DistributedCache;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class Q3DeptEarliestEmp extends Configured implements Tool {

	public static class MapClass extends Mapper<LongWritable, Text, Text, Text> {

		private Map<String, String> deptMap = new HashMap<String, String>();
		private String[] kv;

		@Override
		protected void setup(Context context) throws IOException, InterruptedException {
			BufferedReader in = null;
			try {
				URI[] paths = DistributedCache.getCacheFiles(context.getConfiguration());
				String deptIdName = null;
				for (URI path : paths) {
					if (path.toString().contains("dept")) {
						in = new BufferedReader(new FileReader(path.toString()));
						while (null != (deptIdName = in.readLine())) {

							deptMap.put(deptIdName.split(",")[0], deptIdName.split(",")[1]);
						}
					}
				}
			} catch (IOException e) {
				e.printStackTrace();
			} finally {
				try {
					if (in != null) {
						in.close();
					}
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}

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

			kv = value.toString().split(",");

			if (deptMap.containsKey(kv[7])) {
				if (null != kv[4] && !"".equals(kv[4].toString())) {
					context.write(new Text(deptMap.get(kv[7].trim())), new Text(kv[1].trim() + "," + kv[4].trim()));
				}
			}
		}
	}

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

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

			String empName = null;
			String empEnterDate = null;

			DateFormat df = new SimpleDateFormat("dd-MM月-yy");
			Date earliestDate = new Date();
			String earliestEmp = null;

			for (Text val : values) {
				empName = val.toString().split(",")[0];
				empEnterDate = val.toString().split(",")[1];
				try {
					if (df.parse(empEnterDate).compareTo(earliestDate) < 0) {
						earliestDate = df.parse(empEnterDate);
						earliestEmp = empName;
					}
				} catch (ParseException e) {
					e.printStackTrace();
				}
			}

			context.write(key, new Text("The earliest emp of dept:" + earliestEmp + ", Enter date:" + new SimpleDateFormat("yyyy-MM-dd").format(earliestDate)));
		}
	}

	@Override
	public int run(String[] args) throws Exception {

		Job job = new Job(getConf(), "Q3DeptEarliestEmp");
		job.setJobName("Q3DeptEarliestEmp");

		job.setJarByClass(Q3DeptEarliestEmp.class);
		job.setMapperClass(MapClass.class);
		job.setReducerClass(Reduce.class);

		job.setInputFormatClass(TextInputFormat.class);

		job.setOutputFormatClass(TextOutputFormat.class);
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(Text.class);

		String[] otherArgs = new GenericOptionsParser(job.getConfiguration(), args).getRemainingArgs();
		DistributedCache.addCacheFile(new Path(otherArgs[0]).toUri(), job.getConfiguration());
		FileInputFormat.addInputPath(job, new Path(otherArgs[1]));
		FileOutputFormat.setOutputPath(job, new Path(otherArgs[2]));

		job.waitForCompletion(true);
		return job.isSuccessful() ? 0 : 1;
	}

	public static void main(String[] args) throws Exception {
		int res = ToolRunner.run(new Configuration(), new Q3DeptEarliestEmp(), args);
		System.exit(res);
	}
}