I'm trying to listen to any event in external storage directory, i.e. file added, removed or modified through Android FileObserver but its onEvent method never gets called.
I've tried all of the following solutions:
Android FileObserver [duplicate]
FileObserver instance is being garbage collected
How do you implement a FileObserver from an Android Service
And as for my code, its given below:
Manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.grapgame.fileobserverdemo">
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:name=".AppClass"
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".FileObserverService" />
</application>
</manifest>
Service
public class FileObserverService extends Service {
public static final String TAG = "FileObserverService";
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStart");
final String pathToWatch = android.os.Environment.getExternalStorageDirectory().toString();
Toast.makeText(this, "My Service Started and trying to watch " + pathToWatch, Toast.LENGTH_LONG).show();
AppClass.fileObserver = new FileObserver(pathToWatch) { // set up a file observer to watch this directory on sd card
@Override
public void onEvent(int event, String file) {
Log.d(TAG, "File created [" + pathToWatch + file + "]");
}
};
AppClass.fileObserver.startWatching();
return START_STICKY;
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
AppClass.java
public class AppClass extends Application {
public static FileObserver fileObserver;
@Override
public void onCreate() {
super.onCreate();
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Intent intent = new Intent(this, FileObserverService.class);
startService(intent);
}
}
I've also tried it without AppClass.java, I found this solution on Stackoverflow and tried. I also tried this GitHub code but nothing seems to work.
I know FileObserver is not recursive, for now I'm just trying to listen to one directory.
Any help is highly appreciated.
Use class below RecursiveFileObserver
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;
import android.os.FileObserver;
import android.util.Log;
public class RecursiveFileObserver extends FileObserver {
/**
* Only modification events
*/
public static int CHANGES_ONLY = CREATE | DELETE | CLOSE_WRITE | MOVE_SELF | MOVED_FROM | MOVED_TO;
List<SingleFileObserver> mObservers;
String mPath;
int mMask;
public RecursiveFileObserver(String path) {
this(path, ALL_EVENTS);
}
public RecursiveFileObserver(String path, int mask) {
super(path, mask);
mPath = path;
mMask = mask;
}
@Override
public void startWatching() {
if (mObservers != null) return;
mObservers = new ArrayList<SingleFileObserver>();
Stack<String> stack = new Stack<String>();
stack.push(mPath);
while (!stack.isEmpty()) {
String parent = stack.pop();
mObservers.add(new SingleFileObserver(parent, mMask));
File path = new File(parent);
File[] files = path.listFiles();
if (null == files) continue;
for (File f : files) {
if (f.isDirectory() && !f.getName().equals(".") && !f.getName().equals("..")) {
stack.push(f.getPath());
}
}
}
for (SingleFileObserver sfo : mObservers) {
sfo.startWatching();
}
}
@Override
public void stopWatching() {
if (mObservers == null) return;
for (SingleFileObserver sfo : mObservers) {
sfo.stopWatching();
}
mObservers.clear();
mObservers = null;
}
@Override
public void onEvent(int event, String path) {
switch (event) {
case FileObserver.CREATE:
Log.i("RecursiveFileObserver", "CREATE: " + path);
break;
case FileObserver.MODIFY:
Log.i("RecursiveFileObserver", "MODIFY: " + path);
break;
}
}
/**
* Monitor single directory and dispatch all events to its parent, with full path.
*
* @author uestc.Mobius <[email protected]>
* @version 2011.0121
*/
class SingleFileObserver extends FileObserver {
String mPath;
public SingleFileObserver(String path) {
this(path, ALL_EVENTS);
mPath = path;
}
public SingleFileObserver(String path, int mask) {
super(path, mask);
mPath = path;
}
@Override
public void onEvent(int event, String path) {
String newPath = mPath + "/" + path;
RecursiveFileObserver.this.onEvent(event, newPath);
}
}
}
Your Service will look like this
import android.app.Service;
import android.content.Intent;
import android.os.Environment;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.util.Log;
import java.io.File;
public class FileObserverService extends Service {
public static final String TAG = "FileObserverService";
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand: Service Started");
File sdCard = Environment.getExternalStorageDirectory();
AppClass.fileObserver = new RecursiveFileObserver(sdCard.getAbsolutePath());
AppClass.fileObserver.startWatching();
return START_STICKY;
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onDestroy() {
Log.d(TAG, "onDestroy: Service Destroyed");
}
}
and AppClass like this
public class AppClass extends Application {
public static RecursiveFileObserver fileObserver;
@Override
public void onCreate() {
super.onCreate();
Intent intent = new Intent(this, FileObserverService.class);
startService(intent);
}
}