MapReduce之多数据源输入

package com.uplooking.bigdata.mr.format.in;

import com.uplooking.bigdata.mr.wc.WordCountApp;
import org.apache.hadoop.conf.Configuration;
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.InputFormat;
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.input.MultipleInputs;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;

import java.io.IOException;

/**
 * 如果我们读取的数据不只是一个文件，或者说数据源是多个目录下面的文件
 * 还是来统计单词的出现的次数
 */
public class MultiInFormatApp {
    public static void main(String[] args) throws Exception {
        if(args == null || args.length < 1) {
            System.err.println("Parameter Error!Usage:<output_path>");
            System.exit(-1);
        }
        Path outputpath = new Path(args[0]);
        Configuration conf = new Configuration();
        String jobName = MultiInFormatApp.class.getSimpleName();
        Job job = Job.getInstance(conf, jobName);
        job.setJarByClass(MultiInFormatApp.class);
        /**
         *  job                 The  Job
         *  path                to be added to the list of inputs for the job
         *  inputFormatClass    class to use for this path
         *  mapperClass         class to use for this path
         */
        MultipleInputs.addInputPath(job, new Path("/hello"), TextInputFormat.class, MultiInFormatMapper.class);
        MultipleInputs.addInputPath(job, new Path("/hello.txt"), TextInputFormat.class, MultiInFormatMapper.class);

//        FileInputFormat.setInputPaths(job, inputpath);
//        job.setInputFormatClass(TextInputFormat.class);
//        job.setMapperClass(MultiInFormatMapper.class);
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(LongWritable.class);
        //reducer
        job.setReducerClass(MultiInFormatReducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(LongWritable.class);
        job.setOutputFormatClass(TextOutputFormat.class);
        FileOutputFormat.setOutputPath(job, outputpath);
        job.setNumReduceTasks(1);
        job.waitForCompletion(true);
    }

    static class MultiInFormatMapper extends Mapper<LongWritable, Text, Text, LongWritable> {
        @Override
        protected void map(LongWritable k1, Text v1, Context context) throws IOException, InterruptedException {
            String line = v1.toString();
            String[] splits = line.split(" ");
            for(String word : splits) {
                context.write(new Text(word), new LongWritable(1));
            }
        }
    }

    static class MultiInFormatReducer extends Reducer<Text, LongWritable, Text, LongWritable> {
        @Override
        protected void reduce(Text k2, Iterable<LongWritable> v2s, Context context) throws IOException, InterruptedException {
            long count = 0;
            for(LongWritable lw : v2s) {
                count += lw.get();
            }
            context.write(k2, new LongWritable(count));
        }
    }
}