ApacheLogHadoopExample

RefererCount.java

package org.fukata.hadoop;

import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.hadoop.conf.Configuration;
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.GenericOptionsParser;

public class RefererCount {

	/**
	 * @see http://www.java2s.com/Code/Java/Development-Class/ParseanApachelogfilewithRegularExpressions.htm
	 */
	public static class RefererMapper extends
			Mapper<Object, Text, Text, IntWritable> {

		private static final IntWritable ONE = new IntWritable(1);
		private Text keyReferer = new Text();
		
		private static final int LOG_GROUPS = 9;
		private static String LOG_REGEX = "^([\\d.]+) (\\S+) (\\S+) \\[([\\w:/]+\\s[+\\-]\\d{4})\\] \"(.+?)\" (\\d{3}) (\\d+) \"([^\"]+)\" \"([^\"]+)\"";
		private static Pattern LOG_PATTERN = Pattern.compile(LOG_REGEX);

		protected void map(
				Object key,
				Text value,
				org.apache.hadoop.mapreduce.Mapper<Object, Text, Text, IntWritable>.Context context)
				throws java.io.IOException, InterruptedException {
			Matcher matcher = LOG_PATTERN.matcher(value.toString());
			if (!matcher.matches() || LOG_GROUPS != matcher.groupCount()) {
				return;
			}

			String referer = matcher.group(8);
			keyReferer.set(referer);
			context.write(keyReferer, 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);
		}
	}

	public static void main(String[] args) throws Exception {
		Configuration conf = new Configuration();
		String[] otherArgs = new GenericOptionsParser(conf, args)
				.getRemainingArgs();
		if (otherArgs.length != 2) {
			System.err.println("Usage: org.fukata.hadoop.RefererCount <in> <out>");
			System.exit(2);
		}
		Job job = new Job(conf, "RefererCount");
		job.setJarByClass(RefererCount.class);
		job.setMapperClass(RefererMapper.class);
		job.setCombinerClass(IntSumReducer.class);
		job.setReducerClass(IntSumReducer.class);
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(IntWritable.class);
		FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
		FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
		System.exit(job.waitForCompletion(true) ? 0 : 1);
	}
}