我正使用struts，编写完Action，编译通过，同时也将/home.do
映射到了该Action类，但是当请求home.do是，出现
message： No action instance for path /home could be created
description The server encountered an internal error (No action instance for path /home could be created) that prevented it from fulfilling this request.
可能是action类不能被实例化，请问为什么？