The difference between type and class in Jsp:usebean

<jsp:usebean id= "Mybean" class= "package. Mybean "scope=" Request "></jsp:useBean>

<jsp:usebean id= "Mybean" class= "package. Mybean "scope=" Request "></jsp:useBean>

In both of these usages, when Mybean is not empty, there is no difference between the two in use. But when Mybean is set to NULL, such as Request.setattribute ("Mybean", null), there is a difference between the two in use. Use the class= "package. Mybean "does not throw an exception, use the Type=" package. Mybean "will throw an exception. The reason is that when you use class, you first look for the existence of a mybean within the current scope, if it exists, use the ready-made, or new one if it does not exist. When using type, an exception is thrown if Mybean is not present in the current scope and the type is not specified using either class or Beanname. and class and Beanname must specify the package (that is, the packet is introduced), and the type can not be specified.