import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;

import java.io.IOException;

public class Weather13Mapper extends Mapper<LongWritable, Text,Text, DoubleWritable> {
    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        //super.map(key, value, context);
        String line=value.toString();   //[2018年01月01日  阴/小雨  11℃/8℃  东南风<3级/北风<3级]
        String[] arr=line.split("  ");
        FileSplit inputSplit = (FileSplit) context.getInputSplit();
        String name = inputSplit.getPath().getName ();
//        String t1=name.substring(0,4);
        String t2=name.substring(5,7);
//        String time=t1+"/"+t2;
//        System.out.println(t1+"/"+t2);
        if (arr.length>2){
//            String weather=arr[2];
//            System.out.println(weather);
            String w=arr[2].replace("℃","");
//            System.out.println(w);
            String[] w1=w.split("/");
            double weather=(Double.parseDouble(w1[0])+Double.parseDouble(w1[w1.length-1]))/2;
            context.write(new Text(t2),new DoubleWritable(weather));
        }
    }
}

import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

public class Weather13Reducer extends Reducer<Text, DoubleWritable,Text,DoubleWritable> {
    @Override
    protected void reduce(Text key, Iterable<DoubleWritable> values, Context context) throws IOException, InterruptedException {
        //super.reduce(key, values, context);
        double sum=0;
        double sc=0;
//        double avg_weather=0;
        for (DoubleWritable i:values){
            sum+=i.get();
            sc++;
        }
//        avg_weather=sum/sc;
        context.write(key,new DoubleWritable(Double.parseDouble(String.format("%.1f",sum/sc))));
    }
}

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;

import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.FileOutputStream;
import java.io.IOException;

public class Weather13Runner {
    public static  void  main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
        Configuration conf=new Configuration();
        //创建job
        Job job= Job.getInstance(conf,"weather");
        //设置输入输出路径
        FileInputFormat.addInputPath(job,new Path(args[0]));
        FileOutputFormat.setOutputPath(job,new Path(args[1]));
        //设置运行类
        job.setJarByClass(Weather13Runner.class);
        job.setMapperClass(Weather13Mapper.class);
        job.setReducerClass(Weather13Reducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(DoubleWritable.class);
        System.exit(job.waitForCompletion(true)?0:1);

    }
}