/// <summary>
    /// 控制状态的转换
    /// </summary>
    /// <param name="trans">转换条件</param>
    public void PerformTransition(Transition trans)
    {
        //首先判断传入的转换条件是否为空,为空直接返回
        if (trans == Transition.NullTransition)
        {
            Debug.LogError("the transition is null");
            return;
        }

        //不为空的话,查找此转换条件下能转换成什么状态,返回状态的id
        StateID id = currentstate.GetStateID(trans);

        //如果是空id则返回,说明该状态不能进行这种转换
        if (id == StateID.NullStateID)
        {
            Debug.LogError("this transition will not happen");
            return;
        }

        //以上异常情况都排除,在状态集合中找到相应的状态,并赋值
        FSMState state;

        statesDic.TryGetValue(id, out state);
        currentstate.DoWhileLeaving();
        currentstate = state;
        currentstate.DoWhileEntering();
    }