android开发之简单图片浏览器 读取sdcard图片+形成缩略图+Gallery

//想要的返回值所在的列
String[] projection = { MediaStore.Images.Thumbnails._ID};
//图片信息存储在 android.provider.MediaStore.Images.Thumbnails数据库
//快速查询数据库中的图片对应存放路劲
Cursor cursor = managedQuery(
MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI,
projection, //List of columns to return ：想要他返回的列
null, // Return all rows
null,
null);
int columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Thumbnails._ID);
uriArray = new Uri[cursor.getCount()];//把图片路径放在数组中

while(cursor.moveToNext()&&i<cursor.getCount())
{   //移到指定的位置，遍历数据库
cursor.moveToPosition(i);
uri = Uri.withAppendedPath(MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI,cursor.getInt(columnIndex)+"");
uriArray[i]=uri;
try {
bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri));
if (bitmap != null) {
//将原来的位图转换成新的位图
newBitmap = Bitmap.createScaledBitmap(bitmap,80, 80,true);
bitmap.recycle();//释放内存
if (newBitmap != null) {
publishProgress(new LoadedImage(newBitmap));
}
}
} catch (IOException e) {}
i++;
}