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:
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; // Item点击事件 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); // Todo:初始化VIEw ... 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,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,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,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) { } }; /** * ItemClickSupport的私有构造方法 */ private ItemClickSupport(RecyclerVIEw recyclerVIEw) { mRecyclerVIEw = recyclerVIEw; mRecyclerVIEw.setTag(KEY,this); // 为RecyclerVIEw设置OnChildAttachStatechangelistener事件监听 mRecyclerVIEw.addOnChildAttachStatechangelistener(mAttachListener); } /** * 为RecyclerVIEw设置ItemClickSupport */ public static ItemClickSupport addTo(RecyclerVIEw vIEw) { ItemClickSupport support = (ItemClickSupport) vIEw.getTag(KEY); if (support == null) { support = new ItemClickSupport(vIEw); } return support; } /** * 为RecyclerVIEw移除ItemClickSupport */ public static ItemClickSupport removeFrom(RecyclerVIEw vIEw) { ItemClickSupport support = (ItemClickSupport) vIEw.getTag(KEY); if (support != null) { support.detach(vIEw); } return support; } /** * 为RecyclerVIEw设置点击事件监听 */ public ItemClickSupport setonItemClickListener(OnItemClickListener Listener) { mOnItemClickListener = Listener; return this; } /** * 为RecyclerVIEw设置长按事件监听 */ public ItemClickSupport setonItemLongClickListener(OnItemLongClickListener Listener) { mOnItemLongClickListener = Listener; return this; } /** * 为RecyclerVIEw移除OnChildAttachStatechangelistener事件监听 */ private voID detach(RecyclerVIEw vIEw) { vIEw.removeOnChildAttachStatechangelistener(mAttachListener); vIEw.setTag(KEY,null); } /** * RecyclerVIEw的点击事件监听接口 */ public interface OnItemClickListener { voID onItemClicked(RecyclerVIEw recyclerVIEw,VIEw itemVIEw,int position); } /** * RecyclerVIEw的长按事件监听接口 */ public interface OnItemLongClickListener { boolean onItemLongClicked(RecyclerVIEw recyclerVIEw,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:
/** * Add an {@link OnItemtouchListener} to intercept touch events before they are dispatched * to child vIEws or this vIEw's standard scrolling behavior. * * <p>ClIEnt code may use Listeners to implement item manipulation behavior. Once a Listener * returns true from * {@link OnItemtouchListener#onIntercepttouchEvent(RecyclerVIEw,MotionEvent)} its * {@link OnItemtouchListener#ontouchEvent(RecyclerVIEw,MotionEvent)} method will be called * for each incoming MotionEvent until the end of the gesture.</p> * * @param Listener Listener to add * @see SimpleOnItemtouchListener */ 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:
/** * An implementation of {@link RecyclerVIEw.OnItemtouchListener} that has empty method bodIEs and * default return values. * * You may prefer to extend this class if you don't need to overrIDe all methods. Another * benefit of using this class is future compatibility. As the interface may change,we'll * always provIDe a default implementation on this class so that your code won't break when * you update to a new version of the support library. */ public static class SimpleOnItemtouchListener implements RecyclerVIEw.OnItemtouchListener { <span > </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 *** 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:
// 单击,触摸屏按下时立刻触发 abstract boolean onDown(MotionEvent e); // 抬起,手指离开触摸屏时触发(长按、滚动、滑动时,不会触发这个手势) abstract boolean onSingleTapUp(MotionEvent e); // 短按,触摸屏按下后片刻后抬起,会触发这个手势,如果迅速抬起则不会 abstract voID onShowPress(MotionEvent e); // 长按,触摸屏按下后既不抬起也不移动,过一段时间后触发 abstract voID onLongPress(MotionEvent e); // 滚动,触摸屏按下后移动 abstract boolean onScroll(MotionEvent e1,MotionEvent e2,float distanceX,float distanceY); // 滑动,触摸屏按下后快速移动并抬起,会先触发滚动手势,跟着触发一个滑动手势 abstract boolean onFling(MotionEvent e1,float veLocityX,float veLocityY); OnDoubleTapListener的接口有这几个:
// 双击,手指在触摸屏上迅速点击第二下时触发 abstract boolean onDoubleTap(MotionEvent e); // 双击的按下跟抬起各触发一次 abstract boolean onDoubleTapEvent(MotionEvent e); // 单击确认,即很快的按下并抬起,但并不连续点击第二下 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:
/** * RecyclerVIEw的Item点击事件监听 * * @author liyunlong * @date 2016/11/21 9:42 */ 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)) { // 把事件交给GestureDetector处理 return true; } else { return false; } } /** * 初始化GestureDetector */ private voID initGestureDetector(final RecyclerVIEw recyclerVIEw) { mGestureDetector = new GestureDetectorCompat(recyclerVIEw.getContext(),new GestureDetector.SimpleOnGestureListener() { // 这里选择SimpleOnGestureListener实现类,可以根据需要选择重写的方法 /** * 单击事件 */ @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; } /** * 长按事件 */ @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)); } } /** * 双击事件 */ @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; } }); } /** * RecyclerVIEw的Item点击事件监听接口 * * @author liyunlong * @date 2016/11/21 9:43 */ public interface OnItemClickListener { /** * 当ItemVIEw的单击事件触发时调用 */ voID onItemClick(VIEw vIEw,int position); /** * 当ItemVIEw的长按事件触发时调用 */ voID onItemLongClick(VIEw vIEw,int position); /** * 当ItemVIEw的双击事件触发时调用 */ voID onItemDoubleClick(VIEw vIEw,int position); } /** * RecyclerVIEw的Item点击事件监听实现 * * @author liyunlong * @date 2016/11/21 10:05 */ 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:
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:
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。
感谢阅读,希望能帮助到大家,谢谢大家对本站的支持!
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