I want to observe if any file/folder is added inside /storage/emulated/0/DCIM/Camera
using FileObserver in a service, but it didn’t work. Please tell me if there is anything wrong in my code 🙏. Here is the source code:
AndroidManifest.xml
I added the uses-permission and service tags:
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.dtautosender"> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/> <application 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"> <service android:name=".LogWatcherService"/> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
LogWatcherService.java
I added FileObserver inside the service, and overrided its onEvent method:
package com.example.dtautosender; import android.app.Service; import android.content.Intent; import android.os.FileObserver; import android.os.IBinder; import android.util.Log; import android.widget.Toast; import androidx.annotation.Nullable; import java.io.File; public class LogWatcherService extends Service { private static final String TAG = "LogWatcherService"; public static FileObserver fo; @Nullable @Override public IBinder onBind(Intent intent) { return null; } @Override public int onStartCommand(Intent intent, int flags, int startId) { final File directoryToWatch = new File(android.os.Environment.getExternalStorageDirectory().toString() + "/DCIM/Camera/"); fo = new FileObserver(directoryToWatch.getAbsolutePath(), FileObserver.ALL_EVENTS) { @Override public void onEvent(int event, @Nullable String path) { Log.d(TAG, "onEvent: " + path); } }; fo.startWatching(); Toast.makeText(this, "Log Watcher Service is started", Toast.LENGTH_LONG).show(); Log.d(TAG, "onStartCommand: Log Watcher Service is started and trying to watch: " + directoryToWatch); return START_STICKY; } @Override public void onDestroy() { super.onDestroy(); Toast.makeText(this, "Log Watcher Service is stopped", Toast.LENGTH_LONG).show(); Log.d(TAG, "onDestroy: Log Watcher Service is stopped"); fo.stopWatching(); } }
MainActivity.java
I start the service when opening the app when storage permission is granted:
package com.example.dtautosender; import androidx.annotation.NonNull; import androidx.appcompat.app.AppCompatActivity; import androidx.core.app.ActivityCompat; import androidx.core.content.ContextCompat; import android.Manifest; import android.content.Context; import android.content.Intent; import android.content.pm.PackageManager; import android.graphics.Color; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.TextView; public class MainActivity extends AppCompatActivity { private final int MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE = 1; private static final String TAG = "MainActivity"; private boolean watcherIsEnabled = false; private Context ctx; private Button toggleWatcherButton; private TextView statusTextView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ctx = this; statusTextView = findViewById(R.id.status_text); toggleWatcherButton = findViewById(R.id.watcher_toggle); addEventListeners(); requestPermissions(); } private void addEventListeners() { toggleWatcherButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { startLogWatcherService(); } }); } private void requestPermissions() { if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) { if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.READ_EXTERNAL_STORAGE)) { Log.d(TAG, "requestPermissions: Permission isn't granted"); } else { ActivityCompat.requestPermissions( this, new String[] { Manifest.permission.READ_EXTERNAL_STORAGE }, MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE); } } else { Log.d(TAG, "startLogWatcherService: Permission has already been granted"); startLogWatcherService(); } } private void startLogWatcherService() { if (!watcherIsEnabled) { startService(new Intent(ctx, LogWatcherService.class)); statusTextView.setText("Status: Active"); statusTextView.setTextColor(Color.parseColor("#00FF00")); toggleWatcherButton.setText("Stop Service"); } else { stopService(new Intent(ctx, LogWatcherService.class)); statusTextView.setText("Status: Non-Active"); statusTextView.setTextColor(Color.parseColor("#FF0000")); toggleWatcherButton.setText("Start Service"); } watcherIsEnabled = !watcherIsEnabled; } @Override public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) { super.onRequestPermissionsResult(requestCode, permissions, grantResults); switch (requestCode) { case MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE: { if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { startLogWatcherService(); } else { toggleWatcherButton.setText("Watch file permission isn't granted by the user"); toggleWatcherButton.setEnabled(false); } return; } } } }
I started the application and there is onStartCommand on the log. But the onEvent method is never called when changes happen.
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Answer
I solved this problem by myself. I think the problem is because my Android Studio API level is 30, which “Environment.getExternalStorageDirectory()” is deprecated. So, to solve that I added the following attribute to the application tag in AndroidManifest.xml
android:requestLegacyExternalStorage="true"
Now, my FileObserver is working as expected