This is a multi-threaded java program that takes a filepath and recursively goes through each folder and displays the contents of each
package FileName;
import java.util.*;
import java.io.*;
public class fileCrawler {
private WorkQueue workQ;
static int i = 0;
private class Worker implements Runnable {
private WorkQueue queue;
public Worker(WorkQueue q) {
queue = q;
}
// since main thread has placed all directories into the workQ, we
// know that all of them are legal directories; therefore, do not need
// to try ... catch in the while loop below
public void run() {
String name;
while ((name = queue.remove()) != null) {
File file = new File(name);
String entries[] = file.list();
if (entries == null)
continue;
for (String entry : entries) {
if (entry.compareTo(".") == 0)
continue;
if (entry.compareTo("..") == 0)
continue;
String fn = name + "\\" + entry;
System.out.println(fn);
}
}
}
}
public fileCrawler() {
workQ = new WorkQueue();
}
public Worker createWorker() {
return new Worker(workQ);
}
// need try ... catch below in case the directory is not legal
public void processDirectory(String dir) {
try{
File file = new File(dir);
if (file.isDirectory()) {
String entries[] = file.list();
if (entries != null)
workQ.add(dir);
for (String entry : entries) {
String subdir;
if (entry.compareTo(".") == 0)
continue;
if (entry.compareTo("..") == 0)
continue;
if (dir.endsWith("\\"))
subdir = dir+entry;
else
subdir = dir+"\\"+entry;
processDirectory(subdir);
}
}}catch(Exception e){}
}
public static void main(String Args[]) {
fileCrawler fc = new fileCrawler();
// now start all of the worker threads
int N = 5;
ArrayList<Thread> thread = new ArrayList<Thread>(N);
for (int i = 0; i < N; i++) {
Thread t = new Thread(fc.createWorker());
thread.add(t);
t.start();
}
// now place each directory into the workQ
fc.processDirectory(Args[0]);
// indicate that there are no more directories to add
fc.workQ.finish();
for (int i = 0; i < N; i++){
try {
thread.get(i).join();
} catch (Exception e) {};
}
}
}
package FileName;
import java.util.*;
public class WorkQueue {
//
// since we are providing the concurrency control, can use non-thread-safe
// linked list
//
private LinkedList<String> workQ;
private boolean done; // no more directories to be added
private int size; // number of directories in the queue
public WorkQueue() {
workQ = new LinkedList<String>();
done = false;
size = 0;
}
public synchronized void add(String s) {
workQ.add(s);
size++;
notifyAll();
}
public synchronized String remove() {
String s;
while (!done && size == 0) {
try {
wait();
} catch (Exception e) {};
}
if (size > 0) {
s = workQ.remove();
size--;
notifyAll();
} else
s = null;
return s;
}
public synchronized void finish() {
done = true;
notifyAll();
}
}
