java - Hadoop索引

Question

我正在使用下面的代码，并且在编译此代码时遇到问题。我想要实现的是建立索引词用法，以便每个词都引用文件中每个文件的编号。所以可以说，如果我们在abc.txt中有“boy”，我们会得到类似

男孩/usr/abc.txt:1 3

意思是男孩是文件中的第一个和第三个单词

我在下面使用此代码，并且在编译时看到2个错误。一种是找不到GenericOptionsParser，另一种是找不到文件名。我试图将通用WordCount代码修改为此。有人可以指出我正确的方向吗？

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 WordIndex {

  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 {



      //context.getInputSplit();
      //Path filePath = ((FileSplit) context.getInputSplit()).getPath();
      //String filename = ((FileSplit)context.getInputSplit()).getPath().getName();

      String line = value.toString();
      StringTokenizer itr = new StringTokenizer(line);
      //StringTokenizer itr = new StringTokenizer(value.toString());
      while (itr.hasMoreTokens()) {


      String fileName = ((org.apache.hadoop.mapreduce.lib.input.FileSplit) context.getInputSplit()).getPath().getName();
        word.set(itr.nextToken().toLowerCase().replaceAll("[^a-z]+","") +" "+ filename); // get rid of special char
        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();
    String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
    if (otherArgs.length != 2) {
      System.err.println("Usage: wordcount <in> <out>");
      System.exit(2);

    Job job = Job.getInstance(conf, "word count");
    job.setJarByClass(DocWordIndex.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);
   }
  }
}

Answer 1

我按原样使用了您的代码，并进行了3处修改后就可以编译了:

在以下语句中，将filename更改为fileName(fileName中的“N”大写)

更改:

word.set(itr.nextToken().toLowerCase().replaceAll("[^a-z]+","") +" "+ filename); 

至:

word.set(itr.nextToken().toLowerCase().replaceAll("[^a-z]+","") +" "+ fileName); 

导入的包GenericOptionsParser:

添加以下导入:

import org.apache.hadoop.util.GenericOptionsParser;

job.setJarByClass()错误。它被设置为DocWordIndex.class而不是WordIndex.class。

更改:

job.setJarByClass(DocWordIndex.class);

至:

job.setJarByClass(WordIndex.class);

这为我编译了代码。

我的Maven依赖项是(我正在使用Hadoop 2.7.0):

<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-common</artifactId>
    <version>2.7.0</version>
</dependency>

<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-core</artifactId>
    <version>1.2.1</version>
</dependency>