上接：mapreduce 实现统计词频

提出问题

运行 MapReduce 程序时，如果显示下面警告：

WARN mapreduce.JobResourceUploader: Hadoop command-line option parsing not performed. Implement the Tool interface and execute your application with ToolRunner to remedy this.

分析

说明需要用 ToolRunner 方式提交

解决

其他类不动，只需要用下面类提交即可

package wordcount;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
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.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class Main2 extends Configured implements Tool{
    public static void main(String[] args) throws Exception {

        Configuration config = new Configuration();
        //通过ToolRunner类 执行 覆盖的run()方法
        int res=ToolRunner.run(config, new Main2(), args);
        //退出客户端
        System.exit(res);
    }


    @Override
    public int run(String[] args) throws Exception {
        Job job = Job.getInstance(getConf(),"mywordcount2");
        //设置jar加载路径，不加此代码有时可能会报错
        job.setJarByClass(Main2.class);
        //设置map和reduce类
        job.setMapperClass(WordcountMapper.class);
        job.setReducerClass(WordcountReducer.class);
        //设置map输出 key/value 类型
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(IntWritable.class);
        //设置最终输出 key/value 类型
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        //根据输入参数 设置输入和输出路径
        FileInputFormat.setInputPaths(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
        //提交
//        job.submit();
        boolean result = job.waitForCompletion(true);
        return result?0:1;
    }
}

yarn运行

hadoop jar wordcount.jar top.malaoshi.Main2 /wordcount /result

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