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@gitanuj
Created May 20, 2015 19:15
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A FileObserver for Android which monitors all the files/folders in a directory recursively.
import java.io.File;
import java.util.HashMap;
import java.util.Map;
import java.util.Stack;
import android.os.FileObserver;
/**
* A FileObserver that observes all the files/folders within given directory
* recursively. It automatically starts/stops monitoring new folders/files
* created after starting the watch.
*/
public class RecursiveFileObserver extends FileObserver {
private final Map<String, FileObserver> mObservers = new HashMap<>();
private String mPath;
private int mMask;
private EventListener mListener;
public interface EventListener {
void onEvent(int event, File file);
}
public RecursiveFileObserver(String path, EventListener listener) {
this(path, ALL_EVENTS, listener);
}
public RecursiveFileObserver(String path, int mask, EventListener listener) {
super(path, mask);
mPath = path;
mMask = mask | FileObserver.CREATE | FileObserver.DELETE_SELF;
mListener = listener;
}
private void startWatching(String path) {
synchronized (mObservers) {
FileObserver observer = mObservers.remove(path);
if (observer != null) {
observer.stopWatching();
}
observer = new SingleFileObserver(path, mMask);
observer.startWatching();
mObservers.put(path, observer);
}
}
@Override
public void startWatching() {
Stack<String> stack = new Stack<>();
stack.push(mPath);
// Recursively watch all child directories
while (!stack.empty()) {
String parent = stack.pop();
startWatching(parent);
File path = new File(parent);
File[] files = path.listFiles();
if (files != null) {
for (File file : files) {
if (watch(file)) {
stack.push(file.getAbsolutePath());
}
}
}
}
}
private boolean watch(File file) {
return file.isDirectory() && !file.getName().equals(".") && !file.getName().equals("..");
}
private void stopWatching(String path) {
synchronized (mObservers) {
FileObserver observer = mObservers.remove(path);
if (observer != null) {
observer.stopWatching();
}
}
}
@Override
public void stopWatching() {
synchronized (mObservers) {
for (FileObserver observer : mObservers.values()) {
observer.stopWatching();
}
mObservers.clear();
}
}
@Override
public void onEvent(int event, String path) {
File file;
if (path == null) {
file = new File(mPath);
} else {
file = new File(mPath, path);
}
notify(event, file);
}
private void notify(int event, File file) {
if (mListener != null) {
mListener.onEvent(event & FileObserver.ALL_EVENTS, file);
}
}
private class SingleFileObserver extends FileObserver {
private String filePath;
public SingleFileObserver(String path, int mask) {
super(path, mask);
filePath = path;
}
@Override
public void onEvent(int event, String path) {
File file;
if (path == null) {
file = new File(filePath);
} else {
file = new File(filePath, path);
}
switch (event & FileObserver.ALL_EVENTS) {
case DELETE_SELF:
RecursiveFileObserver.this.stopWatching(filePath);
break;
case CREATE:
if (watch(file)) {
RecursiveFileObserver.this.startWatching(file.getAbsolutePath());
}
break;
}
RecursiveFileObserver.this.notify(event, file);
}
}
}
@rajumark
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Loved it, you made my day

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