public void modifyCategory(HttpServletRequest request, HttpServletResponse response) {
		String categoryName = request.getParameter("categoryName");
		int categoryId = Integer.parseInt(request.getParameter("categoryId"));
		
		BookCategoryDAO bcdao = new BookCategoryDAO();
		
		BookCategory bc = bcdao.querryUseName(categoryName);		
		BookCategory bcNew = bcdao.querry(categoryId);
		bcNew.setName(categoryName);
		
		bcdao.update(bcNew);
		
		try {
			response.sendRedirect("../managerView/categoryManage.jsp");
		} catch(Exception e) {
			e.printStackTrace();			
		}
	}