已解決：下單未成功斷點(diǎn)調(diào)試發(fā)現(xiàn)主要是itemId為null，注意去看

decreaseStock的SQL語句
<update?id="decreaseStock">

??update?item_stock
??set?stock?=?stock-#{amount}
??where?item_id?=?#{itemId}?and?stock>=#{amount}
</update>
原來寫的是where?item_id?=?#{item_id?}?and?stock>=#{amount}，這里參數(shù)錯(cuò)誤，不一致，所以要修改

//庫存扣減
boolean?decreaseStock(Integer?itemId,?Integer?amount)?throws?BusinessException;