如何在mapreduce中按键和值排序？

import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;

// 自定义排序器类
public class CustomSortComparator extends WritableComparator {
    protected CustomSortComparator() {
        super(Text.class, true);
    }

    @Override
    public int compare(WritableComparable a, WritableComparable b) {
        // 按键升序排序
        Text key1 = (Text) a;
        Text key2 = (Text) b;
        return key1.compareTo(key2);
    }
}

public class SortMapper extends Mapper<LongWritable, Text, Text, IntWritable> {
    private final static IntWritable one = new IntWritable(1);
    private Text word = new Text();

    public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        // 将输入数据拆分为单词，并输出键值对
        String line = value.toString();
        String[] words = line.split(" ");
        for (String w : words) {
            word.set(w);
            context.write(word, one);
        }
    }
}

public class SortReducer extends Reducer<Text, IntWritable, Text, IntWritable> {
    private IntWritable result = new IntWritable();

    public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
        // 对相同键的值进行求和，并输出结果
        int sum = 0;
        for (IntWritable val : values) {
            sum += val.get();
        }
        result.set(sum);
        context.write(key, result);
    }
}

public class SortJob {
    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf, "sort");
        job.setJarByClass(SortJob.class);
        job.setMapperClass(SortMapper.class);
        job.setReducerClass(SortReducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        job.setSortComparatorClass(CustomSortComparator.class); // 设置自定义排序器
        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}