IDEA 本地远程执行MapReduce（HA集群）程序找不到自定义Mapper与Reduce类

本文通过IDEA本地执行MR程序的main函数 ，而不是打包成Jar手工放到服务器上运行，发现以下错误提示：No job jar file set，然后在HDFS的/tmp下也没发现有该项目的Jar包，可以推测是任务提交给yarn后，本地并没有将项目打包成Jar提交给ResourceManager，导致找不到Mapper与Reducer类。

所以总体思路就是将项目借助Maven打包成Jar，然后通过添加mapreduce.job.jar的xml配置指定该Jar包在本地的存储路径。注意不能是绝对路径，必须是相对路径（项目文件为根路径），否则还是无法提交成功，但是No job jar file set的提示消失了，却依旧找不到类。

package com.atguigu.mapreduce.wordcount;
 
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
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;
 
import java.io.IOException;
 
public class WordCountDriver {
 
   public static class WordCountReducer extends Reducer {
 
        private IntWritable outV = new IntWritable();
 
        @Override
        protected void reduce(Text key, Iterable values, Reducer.Context context) throws IOException, InterruptedException {
            int sum = 0;
            for (IntWritable value : values) {
                sum += value.get();
            }
            outV.set(sum);
            context.write(key, outV);
        }
    }
 
    public static class WordCountMapper extends Mapper {
 
        private Text outK = new Text();
        private IntWritable outV = new IntWritable(1);
 
        @Override
        protected void map(LongWritable key, Text value, Mapper.Context context) throws IOException, InterruptedException {
 
            // 1.获取一行
            String line = value.toString();
 
            // 2.切割
            String[] words = line.split(" ");
 
            for (String word : words) {
                // 封装outK
                outK.set(word);
                //写出
                context.write(outK, outV);
            }
        }
    }
 
 
    public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException {
 
        // 1 获取job
        Configuration conf = new Configuration();
        conf.set("mapreduce.app-submission.cross-platform", "true");
        conf.set("mapreduce.job.jar","test.jar");
 
        Job job = Job.getInstance(conf);
 
        // 2 设置jar包路径
        job.setJarByClass(WordCountDriver.class);
 
        // 3 关联mapper和reducer
        job.setMapperClass(WordCountMapper.class);
        job.setReducerClass(WordCountReducer.class);
 
        // 4 设置map输出的KV类型
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(IntWritable.class);
 
        // 5 设置最终输出的KV类型
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class );
 
        // 6 设置输入路径和输出路径
//        FileInputFormat.setInputPaths(job, new Path("D:\\BaiduNetdiskDownload\\11_input\\inputword"));
//        FileOutputFormat.setOutputPath(job, new Path("D:\\hadoop\\output\\output1"));
        FileInputFormat.setInputPaths(job, new Path("/input/word.txt"));
        FileOutputFormat.setOutputPath(job, new Path("/output"));
 
        // 7 提交job
        boolean result = job.waitForCompletion(true);
 
        System.exit(result ? 0 : 1);
 
    }
 
}

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