73 lines
2.5 KiB
Java
73 lines
2.5 KiB
Java
import java.io.IOException;
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import java.util.StringTokenizer;
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import org.apache.hadoop.conf.Configuration;
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import org.apache.hadoop.fs.Path;
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import org.apache.hadoop.io.IntWritable;
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import org.apache.hadoop.io.Text;
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import org.apache.hadoop.mapreduce.Job;
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import org.apache.hadoop.mapreduce.Mapper;
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import org.apache.hadoop.mapreduce.Reducer;
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import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
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import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
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public class WordCount {
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// Mapper Class
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public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable> {
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private final static IntWritable one = new IntWritable(1);
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private Text word = new Text();
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public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
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StringTokenizer itr = new StringTokenizer(value.toString());
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while (itr.hasMoreTokens()) {
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word.set(itr.nextToken().toLowerCase().replaceAll("[^a-zA-Z0-9]", ""));
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if (!word.toString().isEmpty()) {
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context.write(word, one);
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}
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}
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}
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}
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// Reducer Class
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public static class IntSumReducer extends Reducer<Text, IntWritable, Text, IntWritable> {
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private IntWritable result = new IntWritable();
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public void reduce(Text key, Iterable<IntWritable> values, Context context)
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throws IOException, InterruptedException {
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int sum = 0;
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for (IntWritable val : values) {
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sum += val.get();
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}
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result.set(sum);
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context.write(key, result);
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}
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}
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public static void main(String[] args) throws Exception {
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if (args.length != 2) {
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System.err.println("Usage: WordCount <input path> <output path>");
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System.exit(-1);
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}
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Configuration conf = new Configuration();
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Job job = Job.getInstance(conf, "word count");
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job.setJarByClass(WordCount.class);
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job.setMapperClass(TokenizerMapper.class);
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job.setCombinerClass(IntSumReducer.class); // optional
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job.setReducerClass(IntSumReducer.class);
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job.setOutputKeyClass(Text.class);
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job.setOutputValueClass(IntWritable.class);
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FileInputFormat.addInputPath(job, new Path(args[0]));
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FileOutputFormat.setOutputPath(job, new Path(args[1]));
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System.exit(job.waitForCompletion(true) ? 0 : 1);
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}
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}
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