3

At the moment I’m using getContentResolver().query()/managedQuery() to get a cursor to retrieve images from the gallery app. Because the APIs I’m using are partly deprecated I wanted to use CursorLoader with LoaderManager.

/**
 * Creates a cursor to access the content defined by the image uri for API
 * version 11 and newer.
 * 
 * @return The created cursor.
 */
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
private Cursor createCursorHoneycomb() {
    String[] projection = {
            MediaStore.Images.Media.DATA
    };
    Cursor cursor = getContentResolver().query(imageUri, projection, null, null, null);

    return cursor;
}

/**
 * Creates a cursor to access the content defined by the image uri from API
 * version 8 to 10.
 * 
 * @return The created cursor.
 */
@SuppressWarnings("deprecation")
@TargetApi(Build.VERSION_CODES.FROYO)
private Cursor createCursorFroyo() {
    String[] projection = {
            MediaStore.Images.Media.DATA
    };
    Cursor cursor = managedQuery(imageUri, projection, null, null, null);

    return cursor;
}

Since I don’t have a ListView I don’t use any adapter. I just set an image bitmap for an ImageView.

/**
 * Sets the image bitmap for the image view.
 */
private void setupImageView() {
    String imagePath = getImagePathFromUri(imageUri);
    Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
    ImageView imageView = (ImageView) findViewById(R.id.image_view);

    imageView.setImageBitmap(bitmap);
}

/**
 * Returns an image path created from the supplied image uri.
 * 
 * @param imageUri The supplied image uri.
 * @return Returns the created image path.
 */
@SuppressWarnings("deprecation")
private String getImagePathFromUri(Uri imageUri) {
    Cursor cursor = null;
    String imagePath = null;

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        cursor = createCursorHoneycomb();
    } else {
        cursor = createCursorFroyo();
    }

    // if image is loaded from gallery
    if (cursor != null) {
        startManagingCursor(cursor);

        int columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);

        cursor.moveToFirst();
        imagePath = cursor.getString(columnIndex);
    }
    // if image is loaded from file manager
    else {
        imagePath = imageUri.getPath();
    }

    return imagePath;
}

Is it possible to use CursorLoader with LoaderManager to load images from the gallery app or a file manager? I cant’t find any solution.

4

3 に答える 3

9

必要に応じて getSupportLoaderManager を呼び出してローダー マネージャーを起動します。

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_CODE) {
        if (resultCode == Activity.RESULT_OK) {
            imageUri = data.getData();
            getSupportLoaderManager().initLoader(0, null, this);
        } else if (resultCode == Activity.RESULT_CANCELED) {
            Toast.makeText(this, "Action canceled.", Toast.LENGTH_LONG).show();
        } else {
            Toast.makeText(this, "Action failed!", Toast.LENGTH_LONG).show();
        }
    }
}

次に、イメージ パスの取得に使用するカーソル ローダーを作成します。

@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    String[] projection = {
            MediaStore.Images.Media.DATA
    };
    CursorLoader cursorLoader = new CursorLoader(this, imageUri, projection, null, null, null);

    return cursorLoader;
}

カーソル ローダーが終了すると、取得したデータを使用して UI を更新します。

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
    if (data != null) {
        int columnIndex = data.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);

        data.moveToFirst();
        imagePath = data.getString(columnIndex);
    } else {
        imagePath = imageUri.getPath();
    }

    setupImageView();
}

やり方はとても簡単です。しかし、onCreateLoader() と onLoadFinished() の使い方を理解する必要がありました。

于 2013-01-20T20:42:52.763 に答える
2

これを交換したいかもしれません

Cursor cursor = managedQuery(imageUri, projection, null, null, null);

これとともに

CursorLoader cursorLoader = new CursorLoader(this, imageUri,
projection, null, null, null);
Cursor cursor = CursorLoader.loadInBackground();
于 2015-09-16T22:41:15.323 に答える
0

CursorLoader を LoaderManager で使用して、ギャラリー アプリまたはファイル マネージャーから画像を読み込むことはできますか?

を公​​開、文書化、およびサポートしている場合のみContentProvider。

于 2013-01-20T15:28:45.587 に答える