BlockingQueueTest.java

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;


public class BlockingQueueTest {

	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		System.out.print("Enter base directory: ");
		String directory = in.nextLine();
		System.out.print("Enter key word: ");
		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();
		}
	}
}

class FileEnumerationTask implements Runnable{
	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){
			e.printStackTrace();
		}
	}
	
	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;
}

class SearchTask implements Runnable{
	
	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){
			e.printStackTrace();
		}
	}
	
	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]%s:%d:%s\n", Thread.currentThread().getName(), file.getPath(), lineNumber, line);
			}
		}
		in.close();
	}
	
	private BlockingQueue<File> queue;
	private String keyword;
}