在hadoop上执行字数统计作业

缺乏、安全感 2022-08-18 05:41 173阅读 0赞

**1.编写WordCount.java文件**

package org.myorg;
    
    import java.io.IOException;
    import java.util.*;
    
    import org.apache.hadoop.fs.Path;
    import org.apache.hadoop.conf.*;
    import org.apache.hadoop.io.*;
    import org.apache.hadoop.mapred.*;
    import org.apache.hadoop.util.*;
    
    public class WordCount {
    
    public static class Map extends MapReduceBase implements 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, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException {
    String line = value.toString();
    StringTokenizer tokenizer = new StringTokenizer(line);
    while (tokenizer.hasMoreTokens()) {
    word.set(tokenizer.nextToken());
    output.collect(word, one);
    }
    }
    }
    
    public static class Reduce extends MapReduceBase implements Reducer<Text, IntWritable, Text, IntWritable> {
    
    public void reduce(Text key, Iterator<IntWritable> values, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException {
    int sum = 0;
    while (values.hasNext()) {
    sum += values.next().get();
    }
    output.collect(key, new IntWritable(sum));
    }
    }
    
    public static void main(String[] args) throws Exception {
    JobConf conf = new JobConf(WordCount.class);
    conf.setJobName("wordcount");
    
    conf.setOutputKeyClass(Text.class);
    conf.setOutputValueClass(IntWritable.class);
    
    conf.setMapperClass(Map.class);
    conf.setCombinerClass(Reduce.class);
    conf.setReducerClass(Reduce.class);
    
    conf.setInputFormat(TextInputFormat.class);
    conf.setOutputFormat(TextOutputFormat.class);
    
    FileInputFormat.setInputPaths(conf, new Path(args[0]));
    FileOutputFormat.setOutputPath(conf, new Path(args[1]));
    
    JobClient.runJob(conf);
    }
    
    }

**2.编译WordCount.java文件，把它制作成可执行jar包**

javac -d . -classpath $HADOOP_HOME/****-core.jar WordCount.java

**3.在org的同级目录上建立manifest.mf**

在里面写上Main-Class: org.myorg.WordCount

**4.保存并执行如下命令**

jar -cvfm count.jar manifest.mf org/

**5.在hdfs上建立文件夹。**

hadoop fs -mkdir /test
        hadoop fs -mkdir /test/in

**6.把wordtestnum.txt文件放入hdfs中**

hadoop fs -put /root/wordtestnum.txt /test

**7.执行作业**

hadoop jar count.jar /test/in /test/out