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  • hadoop 2.x 简单实现wordCount

    简单实现hadoop程序,包括:hadoop2.x的实现写法

    import org.apache.hadoop.conf.Configured;

    import org.apache.hadoop.fs.Path;

    import org.apache.hadoop.io.IntWritable;
    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;
    import org.apache.hadoop.util.Tool;
    import org.apache.hadoop.util.ToolRunner;

    import java.io.IOException;
    import java.util.StringTokenizer;

    /**
    * Created by dell on 2016/7/3.
    */
    public class WordCount extends Configured implements Tool {

    public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable> {
        private final static IntWritable one = new IntWritable();
        private Text word = new Text();
        public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
            StringTokenizer itr = new StringTokenizer(value.toString());
            while(itr.hasMoreElements()) {
            word.set(itr.nextToken());
            context.write(word,one);
            }
        }
    }
    public static class IntSumReducer extends Reducer<Text,IntWritable,Text,IntWritable>{
        private IntWritable result = new IntWritable();
        public void Reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
            int sum = 0;
            for(IntWritable val:values) {
            sum += val.get();
        }
            result.set(sum);
            context.write(key,result);
        }
    }
    @Override
    public int run(String[] args) throws Exception {
         Job job = Job.getInstance(getConf());
         job.setJarByClass(WordCount.class);
         job.setMapperClass(TokenizerMapper.class);
         job.setCombinerClass(IntSumReducer.class);
         job.setReducerClass(IntSumReducer.class);
         job.setNumReduceTasks(Integer.parseInt(args[2])); //设置reducer个数
         job.setOutputKeyClass(Text.class);
         job.setOutputValueClass(IntWritable.class);
         FileInputFormat.addInputPath(job,new Path(args[0]));
         FileOutputFormat.setOutputPath(job,new Path(args[1]));
         job.waitForCompletion(true);
         return 0;
    }
        public static void main(String[] args) throws Exception {
            int res = ToolRunner.run(new Configuration(),new WordCount(),args);
            System.exit(res);
        }
    }

    我不生产知识 我只是知识的搬运工
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  • 原文地址:https://www.cnblogs.com/yyy-blog/p/5638958.html
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