java后台报错，急急急，麻烦大家帮看一下！

Question

这是怎么回事呢

ActionContext ac = invocation.getInvocationContext();

Map params = (Map) ac.getParameters();这一行报错

Answer 1

ActionContext ac = invocation.getInvocationContext();

ac.getSession().put("test","123");
ActionContext actionContext = ActionContext.getContext();

Map session= actionContext.getSession();

String s2=(String)session.get("test");