hadoop的二次排序

package  com.qq;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.hadoop.io.WritableComparable;

public class InfoBean implements WritableComparable<InfoBean>{

    private String account;
    
    private double income;
    
    private double expenses;
    
    private double surplus;
    
    public void set(String account, double income, double expenses){
        this.account = account;
        this.income = income;
        this.expenses = expenses;
        this.surplus = income - expenses;
    }
    
    @Override
    public String toString() {
        return this.income + "\t" + this.expenses + "\t" + this.surplus;
    }

    /**
     * serialize
     */
    public void write(DataOutput out) throws IOException {
        out.writeUTF(account);
        out.writeDouble(income);
        out.writeDouble(expenses);
        out.writeDouble(surplus);
    }

    /**
     * 
     */
    public void readFields(DataInput in) throws IOException {
        this.account = in.readUTF();
        this.income = in.readDouble();
        this.expenses = in.readDouble();
        this.surplus = in.readDouble();
    }
    

    public int compareTo(InfoBean o) {
        if(this.income == o.getIncome()){
            return this.expenses > o.getExpenses() ? 1 : -1; //由低到高排序
        } else {
            return this.income > o.getIncome() ? -1 : 1;  //由高到低排序
        }
    }

    public String getAccount() {
        return account;
    }

    public void setAccount(String account) {
        this.account = account;
    }

    public double getIncome() {
        return income;
    }

    public void setIncome(double income) {
        this.income = income;
    }

    public double getExpenses() {
        return expenses;
    }

    public void setExpenses(double expenses) {
        this.expenses = expenses;
    }

    public double getSurplus() {
        return surplus;
    }

    public void setSurplus(double surplus) {
        this.surplus = surplus;
    }

    
}




package com.qq;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
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;

public class SortStep {

    public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf);
        job.setJarByClass(SortStep.class);
        job.setMapperClass(SortMapper.class);
        job.setMapOutputKeyClass(InfoBean.class);
        job.setMapOutputValueClass(NullWritable.class);
        FileInputFormat.setInputPaths(job, new Path(args[0]));
        job.setReducerClass(SortReducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(InfoBean.class);
        job.setNumReduceTasks(1);
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
        job.waitForCompletion(true);

    }

    public static class SortMapper extends Mapper<LongWritable, Text, InfoBean, NullWritable>{

        private InfoBean bean = new InfoBean();
        
        @Override
        protected void map(LongWritable key, Text value, Context context)
                throws IOException, InterruptedException {
            String line = value.toString();
            String[] fields = line.split(",");
            String account = fields[0];
            double income = Double.parseDouble(fields[1]);        //收入从高到低排序
            double expenses = Double.parseDouble(fields[2]);      //支出从低到高排序
            bean.set(account, income, expenses);
            context.write(bean, NullWritable.get());
        }
        
    }
    
    
    public static class SortReducer extends Reducer<InfoBean, NullWritable, Text, InfoBean>{
        private Text k = new Text();
        @Override
        protected void reduce(InfoBean bean, Iterable<NullWritable> v2s, Context context)
                throws IOException, InterruptedException {
            String account = bean.getAccount();
            k.set(account);
            context.write(k, bean);
        }
        
    }
}