Step5

package com.sxt.hadoop.itemcf;

import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.StringTokenizer;
import java.util.regex.Pattern;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.MapWritable;
import org.apache.hadoop.io.NullWritable;
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.FileSplit;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.MultipleOutputs;
import org.apache.log4j.Logger;
/**
 * 
 * 把相乘之后的矩阵相加获得结果矩阵
 * 
 * @author root
 *
 */
public class Step5 {
	private final static Text K = new Text();
	private final static Text V = new Text();
	public static boolean run(Configuration config, Map<String, String> paths) {
		try {
			FileSystem fs = FileSystem.get(config);
			Job job = Job.getInstance(config);
			job.setJobName("step5");
			job.setJarByClass(StartRun.class);
			job.setMapperClass(Step5_Mapper.class);
			job.setReducerClass(Step5_Reducer.class);
			job.setMapOutputKeyClass(Text.class);
			job.setMapOutputValueClass(Text.class);
			FileInputFormat
					.addInputPath(job, new Path(paths.get("Step5Input")));
			Path outpath = new Path(paths.get("Step5Output"));
			if (fs.exists(outpath)) {
				fs.delete(outpath, true);
			}
			FileOutputFormat.setOutputPath(job, outpath);
			boolean f = job.waitForCompletion(true);
			return f;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return false;
	}
	static class Step5_Mapper extends Mapper<LongWritable, Text, Text, Text> {
		/**
		 * 原封不动输出
		 */
		protected void map(LongWritable key, Text value, Context context)
				throws IOException, InterruptedException {
			String[] tokens = Pattern.compile("[\t,]").split(value.toString());
			Text k = new Text(tokens[0]);// 用户为key
			Text v = new Text(tokens[1] + "," + tokens[2]);
			context.write(k, v);
		}
	}
	static class Step5_Reducer extends Reducer<Text, Text, Text, Text> {
		protected void reduce(Text key, Iterable<Text> values, Context context)
				throws IOException, InterruptedException {
			Map<String, Double> map = new HashMap<String, Double>();// 结果

			//u3  >  reduce
			//101, 11
			//101, 12
			//101, 8
			//102, 12
			//102, 32
			for (Text line : values) {// i9,4.0
				String[] tokens = line.toString().split(",");
				String itemID = tokens[0];
				Double score = Double.parseDouble(tokens[1]);

				if (map.containsKey(itemID)) {
					map.put(itemID, map.get(itemID) + score);// 矩阵乘法求和计算
				} else {
					map.put(itemID, score);
				}
			}
			Iterator<String> iter = map.keySet().iterator();
			while (iter.hasNext()) {
				String itemID = iter.next();
				double score = map.get(itemID);
				Text v = new Text(itemID + "," + score);
				context.write(key, v);
			}
		}
	}
}