使用BlockingQueue在给定的某个文件夹下查找给定的关键字keywords

在给定的某个文件夹下查找给定的关键字keywords

程序源于Java核心技术（卷I）第8版 基础知识（中文版）

作者：Cay S.Horstmann,Gray Cornell ，

第14章多线程中的第14.6节阻塞队列，源码如下：

package v1ch14.BlockingQueueTest;

import java.io.*;
import java.util.*;
import java.util.concurrent.*;

/**
 * @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.println("************ directory = "+directory);
      System.out.print("Enter keyword (e.g. volatile): ");
      String keyword = in.nextLine();
      System.out.println("************ keyword = "+keyword);
      
      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;
}

运行如下：
Enter base directory (e.g. /usr/local/jdk1.6.0/src): D:\all_install\MyEclipse_install\Workspace1\tesst\src\v1ch14

************ directory = D:\all_install\MyEclipse_install\Workspace1\tesst\src\v1ch14

Enter keyword (e.g. volatile): public

************ keyword = public

D:\all_install\MyEclipse_install\Workspace1\tesst\src\v1ch14\AlgorithmAnimation\AlgorithmAnimation.java:15:public class AlgorithmAnimation

D:\all_install\MyEclipse_install\Workspace1\tesst\src\v1ch14\AlgorithmAnimation\AlgorithmAnimation.java:17: public static void main(String[] args)

D:\all_install\MyEclipse_install\Workspace1\tesst\src\v1ch14\AlgorithmAnimation\AlgorithmAnimation.java:21: public void run()

D:\all_install\MyEclipse_install\Workspace1\tesst\src\v1ch14\AlgorithmAnimation\AlgorithmAnimation.java:37: public AnimationFrame()

D:\all_install\MyEclipse_install\Workspace1\tesst\src\v1ch14\AlgorithmAnimation\AlgorithmAnimation.java:47: public void actionPerformed(ActionEvent event)

D:\all_install\MyEclipse_install\Workspace1\tesst\src\v1ch14\UnsynchBankTest\UnsynchBankTest.java:8:public class UnsynchBankTest

............部分结果

看过代码后，对查找某文件夹下的文件中的关键字，有了一定的思路，如下：
1.查找给定文件夹下的所有文件，并放入队列中

2.根据输入的关键字，循环查找某个文件中包含的关键字行

代码通过测试，毕竟是大牛写的，我们小辈只有学习的份，可以直接copy，运行，祝大家好运！