运行Hadoop自带的单词统计程序

目录

​​Java，hadoop环境变量路径​​

​​java单词统计代码​​

​​ubuntu新建文本文件​​

​​编译java文件 成为jar​​

​​hadoop运行jar 代码​​

Java，hadoop环境变量路径

export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
export PATH=PATH
export CLASSPATH=.:JAVA_HOME/lib/tools.jar

export HADOOP_HOME=/home/zjq/had/hadoop-2.7.5
export PATH=HADOOP_HOME/bin:$HADOOP_HOME/sbin

java单词统计代码

import java.io.IOException;
import java.util.StringTokenizer;

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.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

public class WordCount {

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

    private final static IntWritable one = new IntWritable(1);
    private Text word = new Text();

    public void map(Object key, Text value, Context context
                    ) throws IOException, InterruptedException {
      StringTokenizer itr = new StringTokenizer(value.toString());
      while (itr.hasMoreTokens()) {
        word.set(itr.nextToken());
        context.write(word, one);
      }
    }
  }

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

    public void reduce(Text key, Iterable<IntWritable> values,
                       Context context
                       ) throws IOException, InterruptedException {
      int sum = 0;
      for (IntWritable val : values) {
        sum += val.get();
      }
      result.set(sum);
      context.write(key, result);
    }
  }

  public static void main(String[] args) throws Exception {
    Configuration conf = new Configuration();
    Job job = Job.getInstance(conf, "word count");
    job.setJarByClass(WordCount.class);
    job.setMapperClass(TokenizerMapper.class);
    job.setCombinerClass(IntSumReducer.class);
    job.setReducerClass(IntSumReducer.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(IntWritable.class);
    FileInputFormat.addInputPath(job, new Path(args[0]));
    FileOutputFormat.setOutputPath(job, new Path(args[1]));
    System.exit(job.waitForCompletion(true) ? 0 : 1);
  }
}

ubuntu新建文本文件

在window新建，直接拖拽

编译java文件 成为jar

bin/hadoop com.sun.tools.javac.Main WordCount.java  #将WordCount.java编译成三个.class文件
jar cf wc.jar WordCount*.class #将三个.class文件打包成jar文件

hadoop运行jar 代码

bin/hadoop jar wc.jar WordCount /home/zjq/had/hadoop-2.7.5/input /home/zjq/had/hadoop-2.7.5/output 

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