android根据原图片的路径得到该图片的缩略图

/**
* 根据图片的路径得到该图片在表中的ID
* @param cr
* @param fileName
* @return
*/
public static String getImageIdFromPath(ContentResolver cr, String fileName) {

//select condition.
String whereClause = MediaStore.Images.Media.DATA + " = '" + fileName + "'";

//colection of results.
Cursor cursor = cr.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, new String[]{MediaStore.Images.Media._ID}, whereClause, null, null);
if (cursor == null || cursor.getCount() == 0) {
if (cursor != null)
cursor.close();
return null;
}
cursor.moveToFirst();
//image id in image table.
String imageId = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media._ID));
cursor.close();
if (imageId == null) {
return null;
}
return imageId;
}

/**
* 根据图片的ID得到缩略图
* @param cr
* @param imageId
* @return
*/
public static Bitmap getThumbnailsFromImageId(ContentResolver cr, String imageId) {
if (imageId == null || imageId.equals(""))
return null;

Bitmap bitmap = null;
BitmapFactory.Options options = new BitmapFactory.Options();
options.inDither = false;
options.inPreferredConfig = Bitmap.Config.ARGB_8888;

long imageIdLong = Long.parseLong(imageId);
//via imageid get the bimap type thumbnail in thumbnail table.
bitmap = MediaStore.Images.Thumbnails.getThumbnail(cr, imageIdLong, MediaStore.Images.Thumbnails.MINI_KIND, options);

return bitmap;
}