adts.CreateCorrespondences.java Source code

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Here is the source code for adts.CreateCorrespondences.java

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/**************************************************
Copyright (C) 2014  Raptis Dimos <raptis.dimos@yahoo.gr>
    
    
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
    
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
    
You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
**************************************************/

package adts;

import java.io.IOException;
import java.security.*;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.mapreduce.TableMapper;

public class CreateCorrespondences {

    public static class Map extends TableMapper<Text, Text> {
        public static final byte[] TITLE = "title".getBytes();
        public static final byte[] ATTR1 = "".getBytes();

        public void map(ImmutableBytesWritable row, Result value, Context context)
                throws IOException, InterruptedException {
            String val = new String(value.getValue(TITLE, ATTR1));
            String row_key = new String(value.getRow());

            String[] keywords = val.split("_");
            for (int i = 0; i < keywords.length; i++) {
                context.write(new Text(keywords[i]), new Text(row_key));
            }
        }
    }

    public static class Reduce extends Reducer<Text, Text, Text, Text> {
        MessageDigest md;

        public void reduce(Text key, Iterable<Text> values, Context context)
                throws IOException, InterruptedException {
            String keyword = new String(key.toString());
            String md5, value;

            try {
                md = MessageDigest.getInstance("MD5");
            } catch (NoSuchAlgorithmException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            for (Text val : values) {
                md5 = new String(val.toString());
                value = new String(keyword + "," + md5);
                md.update(value.getBytes());
                byte[] thedigest = md.digest();
                StringBuffer sb = new StringBuffer();
                for (int i = 0; i < thedigest.length; i++)
                    sb.append(Integer.toString((thedigest[i] & 0xff) + 0x100, 16).substring(1));
                String keyword_and_article_md5 = key.toString() + "\t" + val.toString();
                context.write(new Text(sb.toString()), new Text(keyword_and_article_md5));
            }

        }
    }

    public static void main(String[] args) throws Exception {
        Configuration config = HBaseConfiguration.create();
        Job job = new Job(config, "CreateCorrespondences");
        job.setJarByClass(CreateCorrespondences.class);

        Scan scan = new Scan();
        scan.setCaching(500); // 1 is the default in Scan, which will be bad for MapReduce jobs
        scan.setCacheBlocks(false); // don't set to true for MR jobs

        TableMapReduceUtil.initTableMapperJob("content", // input HBase table name
                scan, // Scan instance to control CF and attribute selection
                Map.class, // mapper
                Text.class, // mapper output key
                Text.class, // mapper output value
                job);
        job.setReducerClass(Reduce.class);
        job.setNumReduceTasks(1);
        FileOutputFormat.setOutputPath(job, new Path(args[0]));

        boolean b = job.waitForCompletion(true);
        if (!b) {
            throw new IOException("error with job!");
        }
    }

}