WordCount MapReduce怎么使用

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package org.myorg;import java.io.*;import java.util.*;import org.apache.hadoop.fs.Path;import org.apache.hadoop.filecache.DistributedCache;import org.apache.hadoop.conf.*;import org.apache.hadoop.io.*;import org.apache.hadoop.mapred.*;import org.apache.hadoop.util.*;public class WordCount extends Configured implements Tool {    public static class Map extends MapReduceBase implements Mapper {        static enum Counters {INPUT_WORDS}        private final static IntWritable one = new IntWritable(1);        private Text word = new Text();        private boolean caseSensitive = true;        private Set patternsToSkip = new HashSet();        private long numRecords = 0;        private String inputFile;        public void configure(JobConf job) {            caseSensitive = job.getBoolean("wordcount.case.sensitive", true);            inputFile = job.get("map.input.file");            if (job.getBoolean("wordcount.skip.patterns", false)) {                Path[] patternsFiles = new Path[0];                try {                    patternsFiles = DistributedCache.getLocalCacheFiles(job);                } catch (IOException ioe) {                    System.err.println("Caught exception while getting cached files: " + StringUtils.stringifyException(ioe));                }                for (Path patternsFile : patternsFiles) {                    parseSkipFile(patternsFile);                }            }        }        private void parseSkipFile(Path patternsFile) {            try {                BufferedReader fis = new BufferedReader(new FileReader(patternsFile.toString()));                String pattern = null;                while ((pattern = fis.readLine()) != null) {                    patternsToSkip.add(pattern);                }            } catch (IOException ioe) {                System.err.println("Caught exception while parsing the cached file '" + patternsFile + "' : " + StringUtils.stringifyException(ioe));            }        }        public void map(LongWritable key, Text value, OutputCollector output, Reporter reporter) throws IOException {            String line = (caseSensitive) ? value.toString() : value.toString().toLowerCase();            for (String pattern : patternsToSkip) {                line = line.replaceAll(pattern, "");            }            StringTokenizer tokenizer = new StringTokenizer(line);            while (tokenizer.hasMoreTokens()) {                word.set(tokenizer.nextToken());                output.collect(word, one);                reporter.incrCounter(Counters.INPUT_WORDS, 1);            }            if ((++numRecords % 100) == 0) {                reporter.setStatus("Finished processing " + numRecords + " records " + "from the input file: " + inputFile);            }        }    }    public static class Reduce extends MapReduceBase implements Reducer {        public void reduce(Text key, Iterator values, OutputCollector output, Reporter reporter) throws IOException {            int sum = 0;            while (values.hasNext()) {                sum += values.next().get();            }            output.collect(key, new IntWritable(sum));        }    }    public int run(String[] args) throws Exception {        JobConf conf = new JobConf(getConf(), WordCount.class);        conf.setJobName("wordcount");        conf.setOutputKeyClass(Text.class);        conf.setOutputValueClass(IntWritable.class);        conf.setMapperClass(Map.class);        conf.setCombinerClass(Reduce.class);        conf.setReducerClass(Reduce.class);        conf.setInputFormat(TextInputFormat.class);        conf.setOutputFormat(TextOutputFormat.class);        List other_args = new ArrayList();        for (int i = 0; i < args.length; ++i) {            if ("-skip".equals(args[i])) {                DistributedCache.addCacheFile(new Path(args[++i]).toUri(), conf);                conf.setBoolean("wordcount.skip.patterns", true);            } else {                other_args.add(args[i]);            }        }        FileInputFormat.setInputPaths(conf, new Path(other_args.get(0)));        FileOutputFormat.setOutputPath(conf, new Path(other_args.get(1)));        JobClient.runJob(conf);        return 0;    }    public static void main(String[] args) throws Exception {        int res = ToolRunner.run(new Configuration(), new WordCount(), args);        System.exit(res);    }}

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