https://baejangho.com/entry/JAVA-request-array

/* 주문 */
	$('.order').click(function(){
		let orderList = [];
		let prodInfoList = [];
		
		let prodNo 	= $('#prodNo').text().slice(4);
		for(var i = 0 ; i < 6 ; i++){
			if(prodNo[i] != 0){
				prodNo = prodNo.slice(i);
				break;
			}
		}		
		let count 	= $('#count').val();
		let price 	= $('#price').text().split(',').join("");
		let discount= $('#discount').text();
		let delivery= $('#delivery').text().replace('무료배송', '0').split(',').join("");
		let total 	= $('#total').text().split(',').join("");
		let point	= parseInt(price) / 100;
		
		let prodInfo = [
			prodNo, count, price, discount, point, delivery, total
		];
		orderList.push(prodInfo);
		console.log(orderList);
		
		if(confirm('주문하시겠습니까?')){
			$.redirectPost('/Kmarket2/product/order', orderList);
		}
		
	});
	
	
	$.extend({
	    redirectPost: function (location, args) {
	        let form = $('<form></form>');
	        form.attr("method", "post");
	        form.attr("action", location);
	        
	        // key value 형식으로 바꾼 후에 form 으로 변환
	        $.each(args, function (key, value) {
	            let field = $('<input></input>');
	            
	            field.attr('type', 'hidden');
	            field.attr("name", 'orderList');
	            field.attr("value", value);
	            
	            form.append(field);
	        });
	        
	        // 위에서 생성된 폼을 제출 한다
	        $(form).appendTo('body').submit();
	    }
	});

@PostMapping("product/order")
	public String order(Model model, HttpServletRequest req) {
		//model.addAttribute("orderList", orderList);
		String[] items = req.getParameterValues("orderList");
		System.out.println(items[0]);
		return "product/order";
	}