Q4SumCitySalary.java

package com.elon33.mr1;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.net.URI;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

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 Q4SumCitySalary 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())) {
							// key为部门号，value为部门名
							deptMap.put(deptIdName.split(",")[0], deptIdName.split(",")[2]);
						}
					}
				}
			} catch (IOException e) {
				e.printStackTrace();
			} finally {
				try {
					if (in != null) {
						in.close();
					}
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}

		// 【map阶段】通过部门号找出每个部门所有的个体的工资，并输出得到：<部门所对应的城市名,每个个体的工资>
		public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {

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

			if (deptMap.containsKey(kv[7])) {
				if (null != kv[5] && !"".equals(kv[5].toString())) {
					context.write(new Text(deptMap.get(kv[7].trim())), new Text(kv[5].trim()));
				}
			}
		}
	}

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

		// 【reduce阶段】所干的活就是把相同key中的value做一个累加，输出：<城市名,工资总数>
		public void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {

			long sumSalary = 0;
			for (Text val : values) {
				sumSalary += Long.parseLong(val.toString());
			}

			context.write(key, new LongWritable(sumSalary));
		}
	}

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

		Job job = new Job(getConf(), "Q4SumCitySalary");
		job.setJobName("Q4SumCitySalary");

		job.setJarByClass(Q4SumCitySalary.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 Q4SumCitySalary(), args);
		System.exit(res);
	}
}