1、需求：根據tomcat日誌計算url訪問了情況，具體的url如下，
要求：區別統計GET和POST URL訪問量
結果為：訪問方式、URL、訪問量

127.0.0.1 - - [03/Jul/2014:23:36:38 +0800] "GET /course/detail/3.htm HTTP/1.0" 200 38435 0.038
182.131.89.195 - - [03/Jul/2014:23:37:43 +0800] "GET / HTTP/1.0" 301 - 0.000
127.0.0.1 - - [03/Jul/2014:23:38:27 +0800] "POST /service/notes/addViewTimes_23.htm HTTP/1.0"
 
 200 2 0.003
127.0.0.1 - - [03/Jul/2014:23:39:03 +0800] "GET /html/notes/20140617/779.html HTTP/1.0" 200 69539 0.046
127.0.0.1 - - [03/Jul/2014:23:43:00 +0800] "GET /html/notes/20140318/24.html HTTP/1.0" 200 67171 0.049
127.0.0.1 - - [03/Jul/2014:23:43:59 +0800] "POST /service/notes/addViewTimes_779.htm HTTP/1.0" 200 1 0.003
127.0.0.1 - - [03/Jul/2014:23:45:51 +0800] "GET / HTTP/1.0"
 
 200 70044 0.060
127.0.0.1 - - [03/Jul/2014:23:46:17 +0800] "GET /course/list/73.htm HTTP/1.0" 200 12125 0.010
127.0.0.1 - - [03/Jul/2014:23:46:58 +0800] "GET /html/notes/20140609/542.html HTTP/1.0" 200 94971 0.077
127.0.0.1 - - [03/Jul/2014:23:48:31 +0800] "POST /service/notes/addViewTimes_24.htm HTTP/1.0" 200 2 0.003
127.0.0.1 - - [03/Jul/2014:23:48:34 +0800] "POST /service/notes/addViewTimes_542.htm HTTP/1.0"
 
 200 2 0.003
127.0.0.1 - - [03/Jul/2014:23:49:31 +0800] "GET /notes/index-top-3.htm HTTP/1.0" 200 53494 0.041
127.0.0.1 - - [03/Jul/2014:23:50:55 +0800] "GET /html/notes/20140609/544.html HTTP/1.0" 200 183694 0.076
127.0.0.1 - - [03/Jul/2014:23:53:32 +0800] "POST /service/notes/addViewTimes_544.htm HTTP/1.0" 200 2 0.004
127.0.0.1 - - [03/Jul/2014:23:54:53 +0800] "GET /html/notes/20140620/900.html HTTP/1.0" 200 151770 0.054
127.0.0.1 - - [03/Jul/2014:23:57:42 +0800] "GET /html/notes/20140620/872.html HTTP/1.0" 200 52373 0.034
127.0.0.1 - - [03/Jul/2014:23:58:17 +0800] "POST /service/notes/addViewTimes_900.htm HTTP/1.0" 200 2 0.003
127.0.0.1 - - [03/Jul/2014:23:58:51 +0800] "GET / HTTP/1.0" 200 70044 0.057

2.mapper程式：

package cn.edu.bjut.log;

import java.io.IOException;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

public class LogMapper extends Mapper<LongWritable, Text, Text, IntWritable> {

    @Override
    protected void map(LongWritable key, Text value, Context context)
            throws IOException, InterruptedException {
        String line = value.toString().trim();
        String outKey = findKey(line);
        context.write(new Text(outKey), new IntWritable(1));
    }

    private String findKey(String line) {
        String result = null;
        if(line.length() > 0) {
            if(line.indexOf("GET") > -1) {
                result = line.substring(line.indexOf("GET"), line.indexOf("HTTP/1.0"));
            } else if(line.indexOf("POST") > -1) {
                result = line.substring(line.indexOf("POST"), line.indexOf("HTTP/1.0"));
            }
        }
        return result;
    }

}

3.Reducer程式：

package cn.edu.bjut.log;

import java.io.IOException;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

public class LogReducer extends Reducer<Text, IntWritable, Text, LongWritable> {

    @Override
    protected void reduce(Text key, Iterable<IntWritable> values, Context context)
            throws IOException, InterruptedException {
        long num = 0L;
        for(IntWritable value : values) {
            num += value.get();
        }
        context.write(key, new LongWritable(num));
    }

}

4.主程式：

package cn.edu.bjut.log;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

public class MainJob {

    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        Job job = new Job(conf, "log");
        job.setJarByClass(MainJob.class);

        job.setMapperClass(LogMapper.class);
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(IntWritable.class);

        job.setReducerClass(LogReducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(LongWritable.class);

        FileInputFormat.addInputPath(job, new Path(args[0]));
        Path outPath = new Path(args[1]);
        FileSystem fs = FileSystem.get(conf);
        if(fs.exists(outPath)) {
            fs.delete(outPath, true);
        }
        FileOutputFormat.setOutputPath(job, outPath);
        job.waitForCompletion(true);
    }

}