| | 1 | |
| | 2 | {{{ |
| | 3 | #!java |
| | 4 | import java.io.IOException; |
| | 5 | import java.util.StringTokenizer; |
| | 6 | |
| | 7 | import org.apache.hadoop.conf.Configuration; |
| | 8 | import org.apache.hadoop.fs.Path; |
| | 9 | import org.apache.hadoop.io.IntWritable; |
| | 10 | import org.apache.hadoop.io.Text; |
| | 11 | import org.apache.hadoop.mapreduce.Job; |
| | 12 | import org.apache.hadoop.mapreduce.Mapper; |
| | 13 | import org.apache.hadoop.mapreduce.Reducer; |
| | 14 | import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; |
| | 15 | import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; |
| | 16 | import org.apache.hadoop.util.GenericOptionsParser; |
| | 17 | |
| | 18 | public class WordCount { |
| | 19 | |
| | 20 | public static class TokenizerMapper extends |
| | 21 | Mapper<Object, Text, Text, IntWritable> { |
| | 22 | |
| | 23 | private final static IntWritable one = new IntWritable(1); |
| | 24 | private Text word = new Text(); |
| | 25 | |
| | 26 | public void map(Object key, Text value, Context context) |
| | 27 | throws IOException, InterruptedException { |
| | 28 | StringTokenizer itr = new StringTokenizer(value.toString()); |
| | 29 | while (itr.hasMoreTokens()) { |
| | 30 | word.set(itr.nextToken()); |
| | 31 | context.write(word, one); |
| | 32 | } |
| | 33 | } |
| | 34 | } |
| | 35 | |
| | 36 | public static class IntSumReducer extends |
| | 37 | Reducer<Text, IntWritable, Text, IntWritable> { |
| | 38 | private IntWritable result = new IntWritable(); |
| | 39 | |
| | 40 | public void reduce(Text key, Iterable<IntWritable> values, |
| | 41 | Context context) throws IOException, InterruptedException { |
| | 42 | int sum = 0; |
| | 43 | for (IntWritable val : values) { |
| | 44 | sum += val.get(); |
| | 45 | } |
| | 46 | result.set(sum); |
| | 47 | context.write(key, result); |
| | 48 | } |
| | 49 | } |
| | 50 | |
| | 51 | public static void main(String[] args) throws Exception { |
| | 52 | // eclipse using |
| | 53 | // String[] argv = { "/user/hadoop/input", "/user/hadoop/output-wc" }; |
| | 54 | // args = argv; |
| | 55 | |
| | 56 | Configuration conf = new Configuration(); |
| | 57 | |
| | 58 | String[] otherArgs = new GenericOptionsParser(conf, args) |
| | 59 | .getRemainingArgs(); |
| | 60 | if (otherArgs.length != 2) { |
| | 61 | System.err |
| | 62 | .println("Usage: hadoop jar WordCount.jar <input> <output>"); |
| | 63 | System.exit(2); |
| | 64 | } |
| | 65 | |
| | 66 | Job job = new Job(conf, "Word Count"); |
| | 67 | job.setJarByClass(WordCount.class); |
| | 68 | job.setMapperClass(TokenizerMapper.class); |
| | 69 | job.setCombinerClass(IntSumReducer.class); |
| | 70 | job.setReducerClass(IntSumReducer.class); |
| | 71 | job.setOutputKeyClass(Text.class); |
| | 72 | job.setOutputValueClass(IntWritable.class); |
| | 73 | FileInputFormat.addInputPath(job, new Path(args[0])); |
| | 74 | FileOutputFormat.setOutputPath(job, new Path(args[1])); |
| | 75 | CheckAndDelete.checkAndDelete(args[1], conf); |
| | 76 | System.exit(job.waitForCompletion(true) ? 0 : 1); |
| | 77 | } |
| | 78 | } |
| | 79 | |
| | 80 | |
| | 81 | }}} |