public float bigSpeed; //每毫秒最大的移动距离
    private Transform fighterTransform; //游戏对象
    private long lastUpdate; //记录最近一次update的时间
 
    private void Update(){
        //因为仅需要每次移动时刷新位置，所以不需要放在FixedUpdate里
        FollowMouseMove();
    }
 
    private void FollowMouseMove(){
        long now = (System.DateTime.Now.Ticks - 621355968000000000)/10000;
        //首先获取飞机当前位置
        Vector3 fightPos = fighterTransform.position;
        //鼠标当前位置，ScreenToWorldPoint用于转化为游戏内坐标体系
        Vector3 mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
        //2D游戏，抛去z轴信息
        mousePos = new Vector3(mousePos.x, mousePos.y, 0f);
        //飞机鼠标位置的距离
        float distance = Vector3.Distance(fightPos-fix, mousePos);
        //两帧之间最大移动距离，bigSpeed是每毫秒的最大移动距离 Update的调用时间并不准确，为了速度均衡，这里根据时间差值来计算
        float maxLen = ((float)(now - lastUpdate))*bigSpeed;
        Vector3 targetPos; //飞机的目标位置
        //飞机向鼠标位置移动  未超过最大距离
        if(distance <= maxLen){
            targetPos = mousePos;
        }else{
            //三角计算
            float dx = (maxLen*(mousePos.x-fightPos.x))/distance;
            float dy = (maxLen*(mousePos.y-fightPos.y))/distance;
            Vector3 dpos = new Vector3(dx, dy, 0f);
            targetPos = fighterTransform.position + dpos;
        }
        //TODO：targetPos是否超出屏幕范围的判断
        fighterTransform.position = targetPos; //将目标位置复制的游戏对象
        lastUpdate = now;
    }

    private void FollowMouseMove(){
        long now = (System.DateTime.Now.Ticks - 621355968000000000)/10000;
        Vector3 fightPos = fighterTransform.position;
        Vector3 mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);  //WorldToScreenPoint
        mousePos = new Vector3(mousePos.x, mousePos.y, 0f);
        float distance = Vector3.Distance(fightPos, mousePos); //当前距离
        float rank;
        float maxLen = ((float)(now - lastUpdate))*bigSpeed; //实际可以移动的最大距离
        if(distance < maxLen){
            rank = 1;
        }else{
            rank = maxLen/distance;
        }
        Vector3 dpos = (mousePos - fightPos)*rank;
        Vector3 targetPos = fighterTransform.position + dpos;
        //CanNotOUtCamera 出界判断模块
        targetPos = CanNotOUtCamera(targetPos, fighterTransform.localScale);
        fighterTransform.position = targetPos;
        lastUpdate = now;
    }

    transform.SetAsLastSibling();
    bulletsTransform = transform.GetChild(0);

    //代码片段1，加载预制体, 创建对象
    GameObject bullet = Resources.Load("Bullet1") as GameObject; //加载预制体
    bullet = Instantiate(bullet); //使用这种方式加载预制体，必须序列化后才能使用
    bullet.transform.parent = cannonsTransform; //设置父级对象
    bullet.transform.localScale = bulltScale; //设置大小。。。预制体似乎为包含拖到修改大小的信息，这里使用中一个Vector3对象重新设置其大小
    bullet.transform.position = beginPos; //使用一个Vector3对象，设置初始位置
    runingBullets.Add(bullet.transform); //加入到队列
 
    //代码片段2，销毁预制体
    if(...){
        Destroy(runingBullets[i].gameObject); //销毁对象
        runingBullets.RemoveAt(i); //移出队列
    }