xamarin学习笔记A06(安卓RecycleView点击事件)

不念不忘少年蓝@ 2022-06-14 10:50 202阅读 0赞

(每次学习一点xamarin就做个学习笔记视频来加深记忆巩固知识)  
如有不正确的地方，请帮我指正。

**实现RecyclerView中Item的基本点击事件**  
![这里写图片描述][SouthEast]

**准备工作**  
从Nuget下载安装  
Xamarin.Android.Support.v7.AppCompat  
Xamarin.Android.Support.v7.RecyclerView

**第一种实现点击事件的方式**  
主要用到RecyclerView.Adapter类，首先自定义MsgAdapter类继承自这个类，在每个Item视图创建的时候(OnCreateViewHolder)给其设置点击事件，Item视图有两个设置点击事件监听器的方法，一个是普通点击SetOnClickListener()，一个是长按点击SetOnLongClickListener，贴上部分代码：

public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
            {
    View msgItemView = LayoutInflater.From(parent.Context).Inflate(Resource.Layout.MsgItem, parent, false);
                MsgViewHolder holder = new MsgViewHolder(msgItemView);
                msgItemView.SetOnClickListener(this);
                msgItemView.SetOnLongClickListener(this);
                return holder;
            }

接着MsgAdapter实现接口OnClickListener的方法OnClick，实现接口IOnLongClickListener的方法OnLongClick把事件传递到外部(本例子外部即MainActivity)调用。  
贴上部分代码：  
自定义一个接口

public interface IRecyclerViewItemClickListener //自定义的RecyclerView的Item的点击接口
        {
            void OnItemClick(View itemView, int position); //普通Click点击
    
            void OnItemLongClick(View itemView, MsgAdapter.MsgViewHolder msgViewHolder);//长按Click点击
    }

自定义的MsgAdapter类的代码

public class MsgAdapter : RecyclerView.Adapter, IOnClickListener, IOnLongClickListener
        {
            private IRecyclerViewItemClickListener m_IRecyclerViewItemClickListener;
    
            public void SetIRecyclerViewClickListener(IRecyclerViewItemClickListener listener)
            {
                m_IRecyclerViewItemClickListener = listener;
            }
    
            public void OnClick(View v) //普通点击
            {
                int position = m_RecyclerView.GetLayoutManager().GetPosition(v);
                if (m_IRecyclerViewItemClickListener != null)
                    m_IRecyclerViewItemClickListener.OnItemClick(v, position);
            }
    
            public bool OnLongClick(View v) //长按点击
            {
                MsgAdapter.MsgViewHolder holder = m_RecyclerView.GetChildViewHolder(v) as MsgAdapter.MsgViewHolder;
                if (m_IRecyclerViewItemClickListener != null)
                    m_IRecyclerViewItemClickListener.OnItemLongClick(v, holder);
                return true;
            }
        }

**第二种实现点击事件的方式(推荐)**  
主要用到RecyclerView.SimpleOnItemTouchListener和GestureDetector.SimpleOnGestureListener这两个类，使用RecyclerView.AddOnItemTouchListener（…）来添加点击事件

贴上部分代码

// 手势监听器类
        public class MsgSimpleOnGestureListener : GestureDetector.SimpleOnGestureListener
        {
            private RecyclerView m_RecyclerView;
            private IRecyclerViewItemClickListener m_IRecyclerViewClickListerner;
            public MsgSimpleOnGestureListener(RecyclerView rv, IRecyclerViewItemClickListener listener)
            {
                m_RecyclerView = rv;
                m_IRecyclerViewClickListerner = listener;
            }
            public override bool OnSingleTapUp(MotionEvent e)//单击事件
            {
                View child = m_RecyclerView.FindChildViewUnder(e.GetX(), e.GetY());
                if (child != null)
                {
                    RecyclerView.ViewHolder vh = m_RecyclerView.GetChildViewHolder(child);
                    int position = vh.LayoutPosition;
                    if (m_IRecyclerViewClickListerner != null)
                    {
                        m_IRecyclerViewClickListerner.OnItemClick(child, position);
                    }
                }
                return true;
            }
    
            public override void OnLongPress(MotionEvent e)//长按事件
            {
                View child = m_RecyclerView.FindChildViewUnder(e.GetX(), e.GetY());
                if (child != null)
                {
                    MsgAdapter.MsgViewHolder vh = m_RecyclerView.GetChildViewHolder(child) as MsgAdapter.MsgViewHolder;
    
                    if (m_IRecyclerViewClickListerner != null)
                    {
                        m_IRecyclerViewClickListerner.OnItemLongClick(child, vh);
                    }
                }
            }
    }

// Item的触摸监听器类
        public class MsgSimpleOnItemTouchListener : RecyclerView.SimpleOnItemTouchListener
        {
    
            private RecyclerView m_RecyclerView;
            private GestureDetectorCompat m_GestureDetector;
    
            public MsgSimpleOnItemTouchListener(RecyclerView rv, MsgSimpleOnGestureListener simpleOnGestureListener)
            {
                m_RecyclerView = rv;
                m_GestureDetector = new GestureDetectorCompat(rv.Context, simpleOnGestureListener);
            }
    
            public override bool OnInterceptTouchEvent(RecyclerView rv, MotionEvent e)
            {
                if (m_GestureDetector.OnTouchEvent(e))
                    return true;
                else
                    return false;
            }
    
            public override void OnTouchEvent(RecyclerView rv, MotionEvent e)
            {
    
            }
        }

**RecyclerView列表中的Item视图的添加，删除，移动操作**  
对RecyclerView列表中的Item视图的添加，删除，移动操作分别是用到RecyclerView.Adapter里的三个方法：  
NotifyItemInserted(int position)  
NotifyItemRemoved(int position)  
NotifyItemMoved(int fromPosition, int toPosition)

完整代码和视频在我上传的CSDN资源中[http://download.csdn.net/download/junshangshui/9873240][http_download.csdn.net_download_junshangshui_9873240]

[SouthEast]: /images/20220614/f7ded5d135f243e59e106716c952b264.png
[http_download.csdn.net_download_junshangshui_9873240]: http://download.csdn.net/download/junshangshui/9873240