记录自己乐优商城遇到的问题

1.添加有参构造,忘记添加无参构造

  ## 错误提示
  (no Creators, like default construct, exist ): cannot deserialize from Object value (no delegate- or property-based Creator)

2.忘记注入@Autowired

  ## 错误提示
  Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
  java.lang.NullPointerException: null

原文：https://www.cnblogs.com/learning-Java/p/12563574.html