大数据----------二次排序

学习笔记，如有错误，望大佬指点！多谢！

何为二次排序？本人理解，两个数字，同时排序，当第一列数字相等时，按照第二列数字排序！！！

原数据

代码如下：
package TowPaixu;

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

class Towpxmap extends Mapper<LongWritable, Text, Px, NullWritable> {
    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        String line=value.toString();
        String[] word=line.split(\"\\t\");
        String name=word[0];
        int yi=Integer.parseInt(word[1]);
        int er=Integer.parseInt(word[2]);
        context.write(new Px(name,yi,er),NullWritable.get());
    }
}
class Toupxreducer extends Reducer<Px, NullWritable,Text,NullWritable>{
    @Override
    protected void reduce(Px key, Iterable<NullWritable> values, Context context) throws IOException, InterruptedException {
        context.write(new Text(key.toString()),NullWritable.get());
    }
}
class Driver{
    public static void main(String[] args) throws Exception {
        Configuration conf=new Configuration();
        Job job=Job.getInstance(conf);

        job.setMapperClass(Towpxmap.class);
        job.setReducerClass(Toupxreducer.class);
        job.setJarByClass(Driver.class);

        job.setMapOutputKeyClass(Px.class);
        job.setMapOutputValueClass(NullWritable.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(NullWritable.class);

        FileInputFormat.setInputPaths(job,new Path(\"E:\\\\0102.txt\"));
        FileOutputFormat.setOutputPath(job,new Path(\"E:\\\\tmp\"));

        System.exit(job.waitForCompletion(true)?0:1);
    }
}
class Px implements WritableComparable<Px> {
    //数据类型以实际情况而定
    private String name;
    private int yi;
    private int er;
    public Px(){}
    public Px(String a,int b,int c){
        this.name=a;
        this.yi=b;
        this.er=c;
    }
    @Override
    public int compareTo(Px o) {
        if(this.yi==o.getYi()){
            return this.er>o.getEr()?-1:1;//-1为小于,0为等于,1为大于
        }
        else {
            return this.yi>o.getYi()?-1:1;
        }
    }

    @Override
    public void write(DataOutput dataOutput) throws IOException {
        dataOutput.writeUTF(name);
        dataOutput.writeInt(yi);
        dataOutput.writeInt(er);
    }

    @Override
    public void readFields(DataInput dataInput) throws IOException {
        this.name=dataInput.readUTF();
        this.yi=dataInput.readInt();
        this.er=dataInput.readInt();
    }
//右键生成getset
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getYi() {
        return yi;
    }

    public void setYi(int yi) {
        this.yi = yi;
    }

    public int getEr() {
        return er;
    }

    public void setEr(int er) {
        this.er = er;
    }
//右键生成tostring
    @Override
    public String toString() {
        return \"名字:\"+name+\"\\t\"+\"价格:\"+yi+\"\\t\"+\"数量:\"+er;
    }
}

分析效果图：