java - 从SD卡获取图像并在Gridview中显示

Question

我正在尝试从 SD 卡获取所有图像并将它们显示在 GridView 中(包含在 fragment 中)。然而，虽然没有抛出异常，但 gridview 中没有显示任何内容，只是纯黑屏。我不确定问题出在哪里，是 View 的绑定(bind)还是将数据提取到游标中。这是该 fragment 的当前代码:

public class PhotoGridFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> {

// member variables for
private static final int PHOTO_LIST_LOADER = 0x01;
private ImageCursorAdapter adapter;
private Cursor c;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getLoaderManager().initLoader(PHOTO_LIST_LOADER, null, this);

    adapter = new ImageCursorAdapter(getActivity().getApplicationContext(), c);
}

/* R.layout.grid_item,
null, new String[] { MediaStore.Images.Thumbnails.DATA }, new int[] {R.id.grid_item},
CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER); */

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    return inflater.inflate(R.layout.photo_item, container, false);     
}


// Loader manager methods
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    String[] projection = { MediaStore.Images.Thumbnails._ID, MediaStore.Images.Thumbnails.DATA };
    CursorLoader cursorLoader = new CursorLoader(getActivity(),
            MediaStore.Images.Media.EXTERNAL_CONTENT_URI, projection,
            null, null, null);
    return cursorLoader;
}

public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
    adapter.swapCursor(cursor);

}

public void onLoaderReset(Loader<Cursor> cursor) {
    adapter.swapCursor(null);
}

private class ImageCursorAdapter extends CursorAdapter {

    private LayoutInflater mLayoutInflater;
    private Context mContext;

    public ImageCursorAdapter(Context context, Cursor c) {
        super(context, c);
        mContext = context;
        mLayoutInflater = LayoutInflater.from(context);
    }

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        ImageView newView = (ImageView) view.findViewById(R.layout.grid_item);
        String imagePath = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Thumbnails._ID));
        if (imagePath != null && imagePath.length() != 0 && newView != null) {
            newView.setVisibility(ImageView.VISIBLE);
        }
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        View v = mLayoutInflater.inflate(R.layout.grid_item, parent, false);
        return v;
    }


}

该项目的布局文件如下:

photo_item.xml:

<?xml version="1.0" encoding="UTF-8"?>
<GridView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/photo_item"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="24dp"
android:padding="6dp" />

grid_item.xml:

<?xml version="1.0" encoding="utf-8"?>
<ImageView
 xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/grid_item"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="24dp"
android:padding="6dp"

/>

Answer 1

在bindView中，您实际上并没有将imageView的drawable设置为任何内容。您获取图像路径，验证它是真实路径，然后忽略它:) 使用该路径获取可绘制对象!然后将 imageView 的可绘制对象设置为该图像。