Back to project page MediaPicker.
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package com.urza.mediapicker; //from ww w. j av a 2 s . com import android.content.Context; import android.database.ContentObserver; import android.database.Cursor; import android.database.CursorJoiner; import android.net.Uri; import android.os.Handler; import android.provider.MediaStore; import android.support.v4.content.AsyncTaskLoader; import android.util.Log; import java.util.ArrayList; import java.util.Collections; import java.util.List; /** * Created by urza on 25.7.2014. */ public class ImageBaseLoader extends AsyncTaskLoader<List<MediaEntityWrapper>> { // We hold a reference to the Loaders data here. private List<MediaEntityWrapper> mData; private SampleObserver mObserver; private String parent; public ImageBaseLoader(Context ctx, String parent) { // Loaders may be used across multiple Activities (assuming they aren't // bound to the LoaderManager), so NEVER hold a reference to the context // directly. Doing so will cause you to leak an entire Activity's context. // The superclass constructor will store a reference to the Application // Context instead, and can be retrieved with a call to getContext(). super(ctx); this.parent = parent; } /****************************************************/ /** (1) A task that performs the asynchronous load **/ /** * ************************************************ */ public List<MediaEntityWrapper> loadInBackground() { // This method is called on a background thread and should generate a // new set of data to be delivered back to the client. List<MediaEntityWrapper> entityList = new ArrayList<MediaEntityWrapper>(); // TODO: Perform the query here and add the results to 'data'. Log.d("DEBUG_TAG", "Querying Images..."); try { final Uri baseFilesUri = MediaStore.Files.getContentUri("external"); Log.d("DEBUG_TAG", "Files Uri: " + baseFilesUri.toString()); final String[] fileColumns = { MediaStore.Files.FileColumns._ID, MediaStore.Files.FileColumns.MEDIA_TYPE, MediaStore.Files.FileColumns.MIME_TYPE, MediaStore.Files.FileColumns.PARENT, MediaStore.Files.FileColumns.DATA }; final String filesSelection = MediaStore.Files.FileColumns.MEDIA_TYPE + " = ? AND " + MediaStore.Files.FileColumns.PARENT + " = ?"; final String[] filesSelectionArgs = {"" + MediaStore.Files.FileColumns.MEDIA_TYPE_IMAGE, parent}; final String filesOrderBy = MediaStore.Files.FileColumns._ID + " ASC"; Cursor imageCursor = getContext().getContentResolver().query( baseFilesUri, fileColumns, filesSelection, filesSelectionArgs, filesOrderBy); Log.d("DEBUG_TAG", "ImageCursor Returned " + imageCursor.getCount() + " image files"); final Uri imageThumbUri = MediaStore.Images.Thumbnails.getContentUri("external"); Log.d("DEBUG_TAG", "ImageThumbnailsUri: " + imageThumbUri.toString()); final String[] thumbColumns = { MediaStore.Images.Thumbnails.IMAGE_ID, MediaStore.Images.Thumbnails._ID, MediaStore.Images.Thumbnails.KIND, MediaStore.Images.Thumbnails.DATA }; final String thumbSelection = MediaStore.Images.Thumbnails.KIND + " = ?"; final String[] thumbSelectionArgs = {"" + MediaStore.Images.Thumbnails.MINI_KIND}; final String thumbOrderBy = MediaStore.Images.Thumbnails.IMAGE_ID + " ASC"; Cursor thumbCursor = getContext().getContentResolver().query( imageThumbUri, thumbColumns, thumbSelection, thumbSelectionArgs, thumbOrderBy); Log.d("DEBUG_TAG", "ThumbCursor Returned " + thumbCursor.getCount() + " thumb files"); if ((imageCursor != null && imageCursor.getCount() > 0)) { CursorJoiner joiner = new CursorJoiner(imageCursor, new String[]{MediaStore.Files.FileColumns._ID}, thumbCursor, new String[]{MediaStore.Images.Thumbnails.IMAGE_ID}); for (CursorJoiner.Result joinerResult : joiner) { switch (joinerResult) { case LEFT: { MediaEntityWrapper tmpImgEntity = new MediaEntityWrapper(); tmpImgEntity.masterId = imageCursor.getString(imageCursor.getColumnIndex(MediaStore.Files.FileColumns._ID)); tmpImgEntity.parent = imageCursor.getString(imageCursor.getColumnIndex(MediaStore.Files.FileColumns.PARENT)); tmpImgEntity.mimeType = imageCursor.getString(imageCursor.getColumnIndex(MediaStore.Files.FileColumns.MIME_TYPE)); tmpImgEntity.masterDataPath = imageCursor.getString(imageCursor.getColumnIndex(MediaStore.Files.FileColumns.DATA)); entityList.add(tmpImgEntity); break; } case RIGHT: // handle case where a row in cursorB is unique break; case BOTH: { // handle case where a row with the same key is in both cursors MediaEntityWrapper tmpImgEntity = new MediaEntityWrapper(); tmpImgEntity.masterId = imageCursor.getString(imageCursor.getColumnIndex(MediaStore.Files.FileColumns._ID)); tmpImgEntity.parent = imageCursor.getString(imageCursor.getColumnIndex(MediaStore.Files.FileColumns.PARENT)); tmpImgEntity.mimeType = imageCursor.getString(imageCursor.getColumnIndex(MediaStore.Files.FileColumns.MIME_TYPE)); tmpImgEntity.masterDataPath = imageCursor.getString(imageCursor.getColumnIndex(MediaStore.Files.FileColumns.DATA)); tmpImgEntity.thumbId = thumbCursor.getString(thumbCursor.getColumnIndex(MediaStore.Images.Thumbnails._ID)); tmpImgEntity.thumbDataPath = thumbCursor.getString(thumbCursor.getColumnIndex(MediaStore.Images.Thumbnails.DATA)); entityList.add(tmpImgEntity); break; } } } Log.d("DEBUG_TAG", "Created Cursor with " + entityList.size() + " images+thumb"); } imageCursor.close(); thumbCursor.close(); } catch (Exception e) { e.printStackTrace(); } Collections.reverse(entityList); return entityList; } /********************************************************/ /** (2) Deliver the results to the registered listener **/ /** * **************************************************** */ public void deliverResult(List<MediaEntityWrapper> data) { if (isReset()) { // The Loader has been reset; ignore the result and invalidate the data. releaseResources(data); return; } // Hold a reference to the old data so it doesn't get garbage collected. // We must protect it until the new data has been delivered. List<MediaEntityWrapper> oldData = mData; mData = data; if (isStarted()) { // If the Loader is in a started state, deliver the results to the // client. The superclass method does this for us. super.deliverResult(data); } // Invalidate the old data as we don't need it any more. if (oldData != null && oldData != data) { releaseResources(oldData); } } /*********************************************************/ /** (3) Implement the Loaders state-dependent behavior **/ /** * **************************************************** */ protected void onStartLoading() { if (mData != null) { // Deliver any previously loaded data immediately. deliverResult(mData); } // Begin monitoring the underlying data source. if (mObserver == null) { mObserver = new SampleObserver(new Handler()); getContext().getContentResolver().registerContentObserver(MediaStore.Images.Media.getContentUri("external"), true, mObserver); } if (takeContentChanged() || mData == null) { // When the observer detects a change, it should call onContentChanged() // on the Loader, which will cause the next call to takeContentChanged() // to return true. If this is ever the case (or if the current data is // null), we force a new load. System.out.println("ImageBaseLoader.forceLoad called"); forceLoad(); } } protected void onStopLoading() { // The Loader is in a stopped state, so we should attempt to cancel the // current load (if there is one). cancelLoad(); // Note that we leave the observer as is. Loaders in a stopped state // should still monitor the data source for changes so that the Loader // will know to force a new load if it is ever started again. } protected void onReset() { // Ensure the loader has been stopped. onStopLoading(); // At this point we can release the resources associated with 'mData'. if (mData != null) { releaseResources(mData); mData = null; } // The Loader is being reset, so we should stop monitoring for changes. if (mObserver != null) { // TODO: unregister the observer getContext().getContentResolver().unregisterContentObserver(mObserver); mObserver = null; } } public void onCanceled(List<MediaEntityWrapper> data) { // Attempt to cancel the current asynchronous load. super.onCanceled(data); // The load has been canceled, so we should release the resources // associated with 'data'. releaseResources(data); } private void releaseResources(List<MediaEntityWrapper> data) { // For a simple List, there is nothing to do. For something like a Cursor, we // would close it in this method. All resources associated with the Loader // should be released here. } /*********************************************************************/ /** (4) Observer which receives notifications when the data changes **/ /** * ****************************************************************** */ //TODO Implement proper ContentObserver private class SampleObserver extends ContentObserver { public SampleObserver(Handler handler) { super(handler); } public void onChange(boolean selfChange) { super.onChange(selfChange); onContentChanged(); System.out.println("SampleObserver.onChange fired"); } } }