繼承Configured，實現Tool，不在run方法中new Configuration，呼叫run時，用ToolRunner呼叫

package com.kfk.hadoop.mr;

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

public class WordCountUpMR extends Configured implements Tool {

    //1.map
    public static class WordCountMapper extends Mapper<LongWritable, Text,Text, IntWritable>{
        private Text mapOutputKey = new Text();
        private IntWritable mapOutputValue = new IntWritable(1);
        @Override
        protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
            String lineValue = value.toString();
            String[] strs = lineValue.split(" ");
            for (String str:strs){
                mapOutputKey.set(str);
                context.write(mapOutputKey,mapOutputValue);
            }
        }
    }

    //2.reduce
    public static class WordCountReducer extends Reducer<Text,IntWritable, Text,IntWritable>{
        private IntWritable outputValue = new IntWritable();
        @Override
        protected void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
            int count = 0;
            for (IntWritable val:values){
                count+=val.get();
            }
            outputValue.set(count);
            context.write(key,outputValue);
        }
    }

    //3.driver
    public int run(String args[])throws Exception {
        //1)get conf
        Configuration configuration = this.getConf();

        //2)create job
        Job job = Job.getInstance(configuration, this.getClass().getSimpleName());
        job.setJarByClass(this.getClass());

        //3.1)input
        Path path = new Path(args[0]);
        FileInputFormat.addInputPath(job,path);

        //3.2)map
        job.setMapperClass(WordCountMapper.class);
        job.setMapOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);

        //3.3)reduce
        job.setReducerClass(WordCountReducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);

        //3.4)output
        Path output = new Path(args[1]);
        FileOutputFormat.setOutputPath(job,output);

        //3.5)commit
        boolean isSuccess = job.waitForCompletion(true);
        return (isSuccess)?0:1;
    }

    public static void main(String[] args){

        args = new String[]{
        "/user/kfk/data/wc",
        "/user/kfk/data/output1"
        };

        Configuration configuration = new Configuration();
        try {
            Path fileOutPath = new Path(args[1]);
            FileSystem fileSystem = FileSystem.get(configuration);
            if (fileSystem.exists(fileOutPath)){
                fileSystem.delete(fileOutPath,true);
            }

            int status = ToolRunner.run(configuration,new WordCountUpMR(),args);
            System.exit(status);

        }catch (Exception e){
            e.printStackTrace();
        }
    }

}