Mega Code Archive
BlockingQueue Test
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/*
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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