SequenceFileCreator.java

/**
 * Copyright 2008 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.sf.katta.indexing;

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Random;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.SequenceFile.Writer;

/**
 * Illustrates how to create a {@link SequenceFile}.
 * 
 */
public class SequenceFileCreator {

  public static void main(String[] args) {
    if (args.length < 3) {
      System.out.println(getUsage());
      System.exit(-1);
    }
    SequenceFileCreator creator = new SequenceFileCreator();
    try {
      String path = args[0];
      String sampleText = getSampleText(args[1]);
      int numOfRecords = Integer.parseInt(args[2]);

      creator.create(path, sampleText, numOfRecords);
    } catch (Exception e) {
      String msg = "Unable to create SequenceFile. Check your parameters: ";
      System.out.println(msg + getUsage());
      e.printStackTrace();
    }
  }

  private static String getUsage() {
    return "SequnceFileCreator: <targetURI> (e.g. hdfs://path) <pathToTextDocument> <numOfRecords>";
  }

  public void create(String pathString, String sampleText, int num) throws IOException {
    String[] strings = sampleText.split("\n");
    Path path = new Path(pathString);
    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.get(path.toUri(), conf);
    Class<LongWritable> kClass = LongWritable.class;
    Class<Text> vClass = Text.class;
    Writer writer = new SequenceFile.Writer(fs, conf, path, kClass, vClass);
    int numOfLines = strings.length;
    Random random = new Random(System.currentTimeMillis());
    for (int i = 0; i < num; i++) {
      LongWritable key = new LongWritable(i);
      Text value = new Text(strings[random.nextInt(numOfLines)]);
      writer.append(key, value);
    }
    writer.close();
  }

  public static String getSampleText(String path) throws IOException {
    ByteArrayOutputStream buffer = new ByteArrayOutputStream();
    FileInputStream inputStream = new FileInputStream(path);
    byte[] bytes = new byte[1028];
    int lenght = -1;
    while ((lenght = inputStream.read(bytes)) > -1) {
      buffer.write(bytes, 0, lenght);
    }
    inputStream.close();
    return new String(buffer.toByteArray());
  }
}