itunes stuck on extracting software

Are you dogged by the matter that iTunes stuck on extracting software and the process bar is motionless for hours when updating or restoring your iPhone or iPad using iTunes? To tell the truth, this is not an issue weighing too heavily. But it is, assuredly, agonizing. Because iTunes doesn't prompt any error message under the circumstances and you can do nothing but to keep waiting for it to complete. Taking aim at such a problem, 5 fruitful methods are given in the following.