android - Trigger mediascanner on specific path (folder), how to?

Question

I got this class:

import android.content.Context;
import android.media.MediaScannerConnection;
import android.net.Uri;
import android.util.Log;

public class MediaScannerWrapper implements  
MediaScannerConnection.MediaScannerConnectionClient {
    private MediaScannerConnection mConnection;
    private String mPath;
    private String mMimeType;


    // filePath - where to scan; 
    // mime type of media to scan i.e. "image/jpeg". 
    // use "*/*" for any media
    public MediaScannerWrapper(Context ctx, String filePath, String mime){
        mPath = "/sdcard/DCIM/Camera";
        mMimeType = "jpg";
        mConnection = new MediaScannerConnection(ctx, this);
    }

    // do the scanning
    public void scan() {
        mConnection.connect();
    }

    // start the scan when scanner is ready
    public void onMediaScannerConnected() {
        mConnection.scanFile(mPath, mMimeType);
        Log.w("MediaScannerWrapper", "media file scanned: " + mPath);
    }

    public void onScanCompleted(String path, Uri uri) {
        // when scan is completes, update media file tags
    }
}

How to use it in the other class? I don't know how to properly use classes, I tried but nothing is working. I do something wrong, but I don't know what, can someone help me with this.

Answer 1

The Story

Before Android 4.4, we could just send a broadcast to trigger the media scanner on any particular file, or folder or even on the root of the storage. But from 4.4 KitKat, this have been fixed by the Android Developers.

Why do I say fixed? The reason is simple. Sending a broadcast using MEDIA_MOUNTED on the root directory is very expensive. Running the Media Scanner is an expensive operation and the situation gets even worse when the user has got a lot of files in the storage and deep folder structures.

Before Android 4.4

Keep it straight and simple. If you are targeting your app before Android 4.4. But keep in mind not to use it on the root directory unless absolutely necessary.

sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + Environment.getExternalStorageDirectory())));

From Android 4.4

There are two ways for you.

i) The first one is very similar to the previous example, but may not work efficiently and is not recommended too.

sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + Environment.getExternalStorageDirectory())));

ii) Now, let us move on to the most recommended and efficient solution to this problem.

Add the file paths of the files which have been updated, like this, in a String type ArrayList

ArrayList<String> toBeScanned = new ArrayList<String>();
toBeScanned.add(item.getFilePath());

Now you need to run scanFile() static method of the MediaScannerConnection class and pass the String array containing the list of all the files which have been updated and needs to be media scanned.

You can also put a listener to respond when the scanning has been finished for individual files.

String[] toBeScannedStr = new String[toBeScanned.size()];
                toBeScannedStr = toBeScanned.toArray(toBeScannedStr);

                MediaScannerConnection.scanFile(getActivity(), toBeScannedStr, null, new OnScanCompletedListener() {

                    @Override
                    public void onScanCompleted(String path, Uri uri) {
                        System.out.println("SCAN COMPLETED: " + path);

                    }
                });