只有map没有reduce的情况：where查询

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wx61090d1892228 2021-08-04 10:31:40 博主文章分类：hadoop ©著作权

文章标签 apache hadoop mapreduce jar java 文章分类 代码人生

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package com.job;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;

public class Job1 {

    public static class CustomerAgeMapper extends Mapper<Object, Text, IntWritable, Text>{

        private final static Text customer = new Text();

        public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
            String customerString = value.toString();
            String[] customerData = customerString.split(",");

            int age = Integer.parseInt(customerData[2]);
            if (20 <= age && age <= 50) {
                customer.set(value);
                context.write(null, customer);
            }
        }
    }

    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf, "job 1");
        job.setJarByClass(Job1.class);
        job.setMapperClass(CustomerAgeMapper.class);
        job.setOutputKeyClass(IntWritable.class);
        job.setOutputValueClass(Text.class);

        job.setNumReduceTasks(0);

        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}