BlockingQueue Test : BlockingQueue « Threads « Java

1. Java
2. Threads
3. BlockingQueue

BlockingQueue Test

 
/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Scanner;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;

/**
 * @version 1.0 2004-08-01
 * @author Cay Horstmann
 */
public class BlockingQueueTest
{
   public static void main(String[] args)
   {
      Scanner in = new Scanner(System.in);
      System.out.print("Enter base directory (e.g. /usr/local/jdk1.6.0/src): ");
      String directory = in.nextLine();
      System.out.print("Enter keyword (e.g. volatile): ");
      String keyword = in.nextLine();

      final int FILE_QUEUE_SIZE = 10;
      final int SEARCH_THREADS = 100;

      BlockingQueue<File> queue = new ArrayBlockingQueue<File>(FILE_QUEUE_SIZE);

      FileEnumerationTask enumerator = new FileEnumerationTask(queue, new File(directory));
      new Thread(enumerator).start();
      for (int i = 1; i <= SEARCH_THREADS; i++)
         new Thread(new SearchTask(queue, keyword)).start();
   }
}

/**
 * This task enumerates all files in a directory and its subdirectories.
 */
class FileEnumerationTask implements Runnable
{
   /**
    * Constructs a FileEnumerationTask.
    * @param queue the blocking queue to which the enumerated files are added
    * @param startingDirectory the directory in which to start the enumeration
    */
   public FileEnumerationTask(BlockingQueue<File> queue, File startingDirectory)
   {
      this.queue = queue;
      this.startingDirectory = startingDirectory;
   }

   public void run()
   {
      try
      {
         enumerate(startingDirectory);
         queue.put(DUMMY);
      }
      catch (InterruptedException e)
      {
      }
   }

   /**
    * Recursively enumerates all files in a given directory and its subdirectories
    * @param directory the directory in which to start
    */
   public void enumerate(File directory) throws InterruptedException
   {
      File[] files = directory.listFiles();
      for (File file : files)
      {
         if (file.isDirectory()) enumerate(file);
         else queue.put(file);
      }
   }

   public static File DUMMY = new File("");

   private BlockingQueue<File> queue;
   private File startingDirectory;
}

/**
 * This task searches files for a given keyword.
 */
class SearchTask implements Runnable
{
   /**
    * Constructs a SearchTask.
    * @param queue the queue from which to take files
    * @param keyword the keyword to look for
    */
   public SearchTask(BlockingQueue<File> queue, String keyword)
   {
      this.queue = queue;
      this.keyword = keyword;
   }

   public void run()
   {
      try
      {
         boolean done = false;
         while (!done)
         {
            File file = queue.take();
            if (file == FileEnumerationTask.DUMMY)
            {
               queue.put(file);
               done = true;
            }
            else search(file);
         }
      }
      catch (IOException e)
      {
         e.printStackTrace();
      }
      catch (InterruptedException e)
      {
      }
   }

   /**
    * Searches a file for a given keyword and prints all matching lines.
    * @param file the file to search
    */
   public void search(File file) throws IOException
   {
      Scanner in = new Scanner(new FileInputStream(file));
      int lineNumber = 0;
      while (in.hasNextLine())
      {
         lineNumber++;
         String line = in.nextLine();
         if (line.contains(keyword)) System.out.printf("%s:%d:%s%n", file.getPath(), lineNumber,
               line);
      }
      in.close();
   }

   private BlockingQueue<File> queue;
   private String keyword;
}

   
  

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