org.springframework.beans.BeanInstantiationException: Failed to instantiate [demo.Words]: No default constructor found; nested exception is java.lang.NoSuchMethodException: demo.Words.<init>()

org.springframework.beans.BeanInstantiationException: Failed to instantiate [demo.Words]:
 No default constructor found; nested exception is java.lang.NoSuchMethodException: demo.Words.<init>()
或者是:

org.springframework.beans.BeanInstantiationException: Failed to instantiate [Daomain.User]: Is it an abstract class?; nested exception is java.lang.InstantiationException: Daomain.User

这个异常就是实体类的构造函数引起的  

解决方法:

要么不设置构造函数;

要么设置满参构造函数和空参函构造数;..