Uri uri = Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_VCARD_URI,lookupKey);
AssetFileDescriptor fd = contentResolver.openAssetFileDescriptor(uri,"r");
FileInputStream fis = fd.createInputStream();
byte[] buf = new byte[(int)fd.getDeclaredLength()];
if (0 < fis.read(buf))
{
   String vCard = new String(buf);
}