//添加
public void AddItem(Product product, int quantity)
{
CartLine line = lineCollection.Where(p => p.Product.Id == product.Id).FirstOrDefault();
if (line == null)
{
lineCollection.Add(new CartLine(){Product = product, Quantity = quantity});
}
else
{
line.Quantity += quantity;
}
}
//移除
public void RemoveLine(Product product)
{
lineCollection.RemoveAll(p => p.Product.Id == product.Id);
}