Step2

package com.sxt.hadoop.itemcf;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
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.output.FileOutputFormat;
/**
 * 按用户分组，计算所有物品出现的组合列表，得到用户对物品的喜爱度得分矩阵
	u13	i160:1,
	u14	i25:1,i223:1,
	u16	i252:1,
	u21	i266:1,
	u24	i64:1,i218:1,i185:1,
	u26	i276:1,i201:1,i348:1,i321:1,i136:1,
 * @author root
 *
 */
public class Step2 {
	public static boolean run(Configuration config,Map<String, String> paths){
		try {
			FileSystem fs =FileSystem.get(config);
			Job job =Job.getInstance(config);
			job.setJobName("step2");
			job.setJarByClass(StartRun.class);
			job.setMapperClass(Step2_Mapper.class);
			job.setReducerClass(Step2_Reducer.class);
			job.setMapOutputKeyClass(Text.class);
			job.setMapOutputValueClass(Text.class);
			FileInputFormat.addInputPath(job, new Path(paths.get("Step2Input")));
			Path outpath=new Path(paths.get("Step2Output"));
			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 Step2_Mapper extends Mapper<LongWritable, Text, Text, Text>{
		 //如果使用：用户+物品，同时作为输出key，更优
		 //i161,u2625,click,2014/9/18 15:03
		protected void map(LongWritable key, Text value,
				Context context)
				throws IOException, InterruptedException {
			String[]  tokens=value.toString().split(",");
			String item=tokens[0];
			String user=tokens[1];
			String action =tokens[2];
			Text k= new Text(user);
			Integer rv =StartRun.R.get(action);
			Text v =new Text(item+":"+ rv.intValue());
			context.write(k, v);
			//u2625    i161:1
		}
	}
	 static class Step2_Reducer extends Reducer<Text, Text, Text, Text>{

			protected void reduce(Text key, Iterable<Text> i,
					Context context)
					throws IOException, InterruptedException {
				Map<String, Integer> r =new HashMap<String, Integer>();
				//u2625
				// i161:1
				// i161:2
				// i161:4
				// i162:3
				// i161:4
				for(Text value :i){
					String[] vs =value.toString().split(":");
					String item=vs[0];
					Integer action=Integer.parseInt(vs[1]);
					action = ((Integer) (r.get(item)==null?  0:r.get(item))).intValue() + action;
					r.put(item,action);
				}
				StringBuffer sb =new StringBuffer();
				for(Entry<String, Integer> entry :r.entrySet() ){
					sb.append(entry.getKey()+":"+entry.getValue().intValue()+",");
				}
				context.write(key,new Text(sb.toString()));
			}
		}
}