The requested resource (/staf/staf_addStaf.action) is not available. 和 There is no Action mapped f

The requested resource （***.action) is not available.  和  There is no Action mapped for namespace / and action name**以及There is no  Action mapped for action name ***.action

The requested resource （***.action) is not available.  是把空间写错了或者是action的名字写错了，直接就没有这样的空间，或者是没有action,它没有在后台报错。

There is no Action mapped for namespace / and action name**会在后台报错············

There is no  Action mapped for action name ***.action.会在后台报错·····················

是怎样的呢？大家发表一下吧！