RecyclerView的Item点击事件实现总结
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自从开始使用RecyclerView
代替ListView,
会发现有很多地方需要学习。前一段时间的学习记录有:
RecyclerView的滚动事件研究 - DevWiki
RecyclerView的ViewHolder和Adapter的封装优化 - DevWiki
RecyclerView问题记录 - DevWiki
实现 RecyclerView
的Item的点击事件有三种方式:
在创建 ItemView
时添加点击监听
当 ItemView attach RecyclerView
时实现
通过RecyclerView
已有的方法addOnItemTouchListener()
实现
1.在创建ItemView
时添加点击监听
思路是:因为ViewHolder我们可以拿到每个Item的根布局,所以如果我们为根布局设置单独的OnClick监听并将其开放给Adapter,那不就可以在组装RecyclerView时就能够设置ItemClickListener,只不过这个Listener不是设置到RecyclerView上而是设置到Adapter。具体实现代码如下:
- public class SampleAdapter extends RecyclerView.Adapter<SampleAdapter.SampleViewHolder> {
-
- private List<DataBean> mDatas;
- private OnItemClickListener mListener;
-
- public DataBean getItem(int position) {
- return mDatas == null ? null : mDatas.get(position);
- }
-
- @Override
- public SampleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
- View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item, parent,false);
- return new SampleViewHolder(itemView);
- }
-
- @Override
- public void onBindViewHolder(SampleViewHolder holder, int position) {
-
- }
-
- @Override
- public int getItemCount() {
- return mDatas == null ? 0 : mDatas.size();
- }
-
- class SampleViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener {
-
- public SampleViewHolder(View itemView) {
- super(itemView);
-
- ...
-
- itemView.setOnClickListener(this);
- itemView.setOnLongClickListener(this);
- }
-
- @Override
- public void onClick(View v) {
- if (mListener != null) {
- mListener.onItemClick(SampleAdapter.this, v, getLayoutPosition());
- }
- }
-
- @Override
- public boolean onLongClick(View v) {
- if (mListener != null) {
- mListener.onItemLongClick(SampleAdapter.this, v, getLayoutPosition());
- return true;
- }
- return false;
- }
- }
- }
2.当ItemView attach RecyclerView时实现
该实现方法是在阅读国外的一篇博客时发现的,原文链接如下:Getting your clicks on RecyclerView
实现的代码如下:
- public class ItemClickSupport {
-
- private static final int KEY = 0x99999999;
- private final RecyclerView mRecyclerView;
- private OnItemClickListener mOnItemClickListener;
- private OnItemLongClickListener mOnItemLongClickListener;
-
- private View.OnClickListener mOnClickListener = new View.OnClickListener() {
- @Override
- public void onClick(View v) {
- if (mOnItemClickListener != null) {
- RecyclerView.ViewHolder holder = mRecyclerView.getChildViewHolder(v);
- mOnItemClickListener.onItemClicked(mRecyclerView, v, holder.getAdapterPosition());
- }
- }
- };
-
- private View.OnLongClickListener mOnLongClickListener = new View.OnLongClickListener() {
- @Override
- public boolean onLongClick(View v) {
- if (mOnItemLongClickListener != null) {
- RecyclerView.ViewHolder holder = mRecyclerView.getChildViewHolder(v);
- return mOnItemLongClickListener.onItemLongClicked(mRecyclerView, v, holder.getAdapterPosition());
- }
- return false;
- }
- };
-
- private RecyclerView.OnChildAttachStateChangeListener mAttachListener = new RecyclerView.OnChildAttachStateChangeListener() {
-
- @Override
- public void onChildViewAttachedToWindow(View view) {
- if (mOnItemClickListener != null) {
- view.setOnClickListener(mOnClickListener);
- }
- if (mOnItemLongClickListener != null) {
- view.setOnLongClickListener(mOnLongClickListener);
- }
- }
-
- @Override
- public void onChildViewDetachedFromWindow(View view) {
- }
- };
-
-
-
-
- private ItemClickSupport(RecyclerView recyclerView) {
- mRecyclerView = recyclerView;
- mRecyclerView.setTag(KEY, this);
-
- mRecyclerView.addOnChildAttachStateChangeListener(mAttachListener);
- }
-
-
-
-
- public static ItemClickSupport addTo(RecyclerView view) {
- ItemClickSupport support = (ItemClickSupport) view.getTag(KEY);
- if (support == null) {
- support = new ItemClickSupport(view);
- }
- return support;
- }
-
-
-
-
- public static ItemClickSupport removeFrom(RecyclerView view) {
- ItemClickSupport support = (ItemClickSupport) view.getTag(KEY);
- if (support != null) {
- support.detach(view);
- }
- return support;
- }
-
-
-
-
- public ItemClickSupport setOnItemClickListener(OnItemClickListener listener) {
- mOnItemClickListener = listener;
- return this;
- }
-
-
-
-
- public ItemClickSupport setOnItemLongClickListener(OnItemLongClickListener listener) {
- mOnItemLongClickListener = listener;
- return this;
- }
-
-
-
-
- private void detach(RecyclerView view) {
- view.removeOnChildAttachStateChangeListener(mAttachListener);
- view.setTag(KEY, null);
- }
-
-
-
-
- public interface OnItemClickListener {
- void onItemClicked(RecyclerView recyclerView, View itemView, int position);
- }
-
-
-
-
- public interface OnItemLongClickListener {
- boolean onItemLongClicked(RecyclerView recyclerView, View itemView, int position);
- }
- }
上面的代码中给RecyclerView
设置了OnChildAttachStateChangeListener
事件监听,当子View attach RecyclerView
时设置事件监听。
- private RecyclerView.OnChildAttachStateChangeListener mAttachListener = new RecyclerView.OnChildAttachStateChangeListener() {
-
- @Override
- public void onChildViewAttachedToWindow(View view) {
- if (mOnItemClickListener != null) {
- view.setOnClickListener(mOnClickListener);
- }
- if (mOnItemLongClickListener != null) {
- view.setOnLongClickListener(mOnLongClickListener);
- }
- }
-
- @Override
- public void onChildViewDetachedFromWindow(View view) {}
- };
使用时只需要调用addTo(RecycleView view)方法得到ItemClickSupport对象,然后调用setOnItemClickListener()方法和setOnItemLongClickListener()方法设置ItemView的点击事件和长按事件监听即可。3.通过RecyclerView
已有的方法addOnItemTouchListener()
实现
3.1、查看源码
查看RecyclerView
源码可以看到,RecyclerView
预留了一个Item的触摸事件方法:
-
-
-
-
-
-
-
-
-
-
-
-
-
- public void addOnItemTouchListener(OnItemTouchListener listener) {
- mOnItemTouchListeners.add(listener);
- }
通过注释我们可知,此方法是在滚动事件之前调用,需要传入一个OnItemTouchListener
对象。OnItemTouchListener
的代码如下:- public static interface OnItemTouchListener {
-
- public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e);
-
- public void onTouchEvent(RecyclerView rv, MotionEvent e);
-
- public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept);
- }
此接口还提供了一个实现类,且官方推荐使用该实现类SimpleOnItemTouchListener:
-
-
-
-
-
-
-
-
-
- public static class SimpleOnItemTouchListener implements RecyclerView.OnItemTouchListener {
- <span style="font-family:'Microsoft YaHei';">
- </span> @Override
- public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
- return false;
- }
-
- @Override
- public void onTouchEvent(RecyclerView rv, MotionEvent e) {
- }
-
- @Override
- public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
- }
- }
在触摸接口中,当触摸时会回调一个MotionEvent对象,通过使用GestureDetectorCompat来解析用户的操作。
3.2、了解GestureDetector的工作原理
对于触摸屏,其原生的消息无非按下、抬起、移动这几种,我们只需要简单重载onTouch或者设置触摸侦听器setOnTouchListener即可进行处理。不过,为了提高我们的APP的用户体验,有时候我们需要识别用户的手势,Android给我们提供的手势识别工具GestureDetector就可以帮上大忙了。
GestureDetector的工作原理是,当我们接收到用户触摸消息时,将这个消息交给GestureDetector去加工,我们通过设置侦听器获得GestureDetector处理后的手势。
GestureDetector提供了两个侦听器接口,OnGestureListener处理单击类消息,OnDoubleTapListener处理双击类消息。
OnGestureListener的接口有这几个:
-
- abstract boolean onDown(MotionEvent e);
-
- abstract boolean onSingleTapUp(MotionEvent e);
-
- abstract void onShowPress(MotionEvent e);
-
- abstract void onLongPress(MotionEvent e);
-
- abstract boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY);
-
- abstract boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY);
OnDoubleTapListener的接口有这几个:-
- abstract boolean onDoubleTap(MotionEvent e);
-
- abstract boolean onDoubleTapEvent(MotionEvent e);
-
- abstract boolean onSingleTapConfirmed(MotionEvent e);
有时候我们并不需要处理上面所有手势,方便起见,Android提供了另外一个类SimpleOnGestureListener实现了如上接口,我们只需要继承SimpleOnGestureListener然后重载需要的手势即可。
3.3、实现点击事件监听
了解了GestureDetector的工作原理之后,便开始实现RecycleView的Item的点击事件。首先写一个SimpleRecycleViewItemClickListener类继承SimpleOnItemTouchListener,构造时传入Item点击回调OnItemClickListener,并覆写父类的boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e)方法,具体代码如下:
-
-
-
-
-
-
- public class SimpleRecycleViewItemClickListener extends RecyclerView.SimpleOnItemTouchListener {
-
- private OnItemClickListener mListener;
- private GestureDetectorCompat mGestureDetector;
-
- public SimpleRecycleViewItemClickListener(OnItemClickListener listener) {
- this.mListener = listener;
- }
-
- @Override
- public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
- if (mGestureDetector == null) {
- initGestureDetector(rv);
- }
- if (mGestureDetector.onTouchEvent(e)) {
- return true;
- } else {
- return false;
- }
- }
-
-
-
-
- private void initGestureDetector(final RecyclerView recyclerView) {
- mGestureDetector = new GestureDetectorCompat(recyclerView.getContext(), new GestureDetector.SimpleOnGestureListener() {
-
-
-
-
- @Override
- public boolean onSingleTapUp(MotionEvent e) {
- View childView = recyclerView.findChildViewUnder(e.getX(), e.getY());
- if (childView != null && mListener != null) {
- mListener.onItemClick(childView, recyclerView.getChildLayoutPosition(childView));
- return true;
- }
- return false;
- }
-
-
-
-
- @Override
- public void onLongPress(MotionEvent e) {
- View childView = recyclerView.findChildViewUnder(e.getX(), e.getY());
- if (childView != null && mListener != null) {
- mListener.onItemLongClick(childView, recyclerView.getChildLayoutPosition(childView));
- }
- }
-
-
-
-
- @Override
- public boolean onDoubleTapEvent(MotionEvent e) {
- int action = e.getAction();
- if (action == MotionEvent.ACTION_UP) {
- View childView = recyclerView.findChildViewUnder(e.getX(), e.getY());
- if (childView != null && mListener != null) {
- mListener.onItemDoubleClick(childView, recyclerView.getChildLayoutPosition(childView));
- return true;
- }
- }
- return false;
- }
-
- });
-
- }
-
-
-
-
-
-
-
- public interface OnItemClickListener {
-
-
-
-
- void onItemClick(View view, int position);
-
-
-
-
- void onItemLongClick(View view, int position);
-
-
-
-
- void onItemDoubleClick(View view, int position);
- }
-
-
-
-
-
-
-
-
- public class SimpleOnItemClickListener implements OnItemClickListener {
-
- @Override
- public void onItemClick(View view, int position) {
-
- }
-
- @Override
- public void onItemLongClick(View view, int position) {
-
- }
-
- @Override
- public void onItemDoubleClick(View view, int position) {
-
- }
- }
- }
在GestureDetectorCompat的手势回调中我们覆写:
boolean onSingleTapUp(MotionEvent e):单击事件回调
void onLongPress(MotionEvent e):长按事件回调
boolean onDoubleTapEvent(MotionEvent e):双击事件回调
如果我们只需要监听单击事件,而不需要监听长按事件和双击事件,构造SimpleRecycleViewItemClickListener时只需要传入SimpleOnItemClickListener即可,如果需要处理其它的手势监听,也可以覆写对应的手势回调方法。
4.三种方法对比
以上三种方式分别是:
在创建ItemView
时添加点击监听
当ItemView
attach RecyclerView
时实现
通过RecyclerView
已有的方法addOnItemTouchListener()
实现
从以上三种方式的实现过程可知:
三种均可实现ItemView
的点击事件和长按事件的监听。
第一种和第二种方式可以很方便对ItemView
中的子View
进行监听。
第三种方式可以很方便获取用户点击的坐标。
第二种方式和第三种方式可以写在单独的类中,相对于第一种写在Adapter
的方式可使代码更独立整洁。
综上所述:
如果你只想监听ItemView
的点击事件或长按事件,三种方式均可。
如果你想监听ItemView
中每个子View
的点击事件,采用第一种或者第二种比较方便。
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