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BaseRecyclerViewAdapterHelper开源项目之点击事件源码学习
阅读量：7095 次
发布时间：2019-06-28

本文共 18154 字，大约阅读时间需要 60 分钟。

hot3.png

##version:2.8.5

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今天我们主要来分析BaseRecyclerViewAdapterHelper为view提供监听点击事件能力的相关源码。

public abstract class SimpleClickListener implements RecyclerView.OnItemTouchListener {private GestureDetectorCompat mGestureDetector;private RecyclerView recyclerView;protected BaseQuickAdapter baseQuickAdapter;public static String TAG = "SimpleClickListener";private boolean mIsPrepressed = false;private boolean mIsShowPress = false;private View mPressedView = null;[@Override](https://my.oschina.net/u/1162528)public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {    Log.i(TAG,">>>>onInterceptTouchEvent e"+e.getActionMasked());    if (recyclerView == null) {        this.recyclerView = rv;        this.baseQuickAdapter = (BaseQuickAdapter) recyclerView.getAdapter();        mGestureDetector = new GestureDetectorCompat(recyclerView.getContext(), new ItemTouchHelperGestureListener(recyclerView));    }else if (recyclerView!=rv){        this.recyclerView = rv;        this.baseQuickAdapter = (BaseQuickAdapter) recyclerView.getAdapter();        mGestureDetector = new GestureDetectorCompat(recyclerView.getContext(), new ItemTouchHelperGestureListener(recyclerView));    }    if (!mGestureDetector.onTouchEvent(e) && e.getActionMasked() == MotionEvent.ACTION_UP && mIsShowPress) {        if (mPressedView!=null){            BaseViewHolder vh = (BaseViewHolder) recyclerView.getChildViewHolder(mPressedView);            if (vh == null ||!isHeaderOrFooterView(vh.getItemViewType())) {                mPressedView.setPressed(false);            }        }        mIsShowPress = false;        mIsPrepressed = false;    }    return false;}[@Override](https://my.oschina.net/u/1162528)public void onTouchEvent(RecyclerView rv, MotionEvent e) {    Log.i(TAG,">>>>onTouchEvent e"+e.getActionMasked());    mGestureDetector.onTouchEvent(e);}[@Override](https://my.oschina.net/u/1162528)public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {    Log.i(TAG,">>>>onRequestDisallowInterceptTouchEvent disallowIntercept"+disallowIntercept);}private class ItemTouchHelperGestureListener extends GestureDetector.SimpleOnGestureListener {    private RecyclerView recyclerView;    ItemTouchHelperGestureListener(RecyclerView recyclerView) {        this.recyclerView = recyclerView;    }    [@Override](https://my.oschina.net/u/1162528)    public boolean onDown(MotionEvent e) {        mIsPrepressed = true;        mPressedView = recyclerView.findChildViewUnder(e.getX(), e.getY());        super.onDown(e);        return false;    }    [@Override](https://my.oschina.net/u/1162528)    public void onShowPress(MotionEvent e) {        Log.i(TAG,">>>>onShowPress e"+e);        if (mIsPrepressed && mPressedView != null) {    //    mPressedView.setPressed(true);            mIsShowPress = true;        }        super.onShowPress(e);    }    @Override    public boolean onSingleTapUp(MotionEvent e) {        Log.i(TAG,">>>>onSingleTapUp e"+e);        if (mIsPrepressed && mPressedView != null) {            if (recyclerView.getScrollState()!=RecyclerView.SCROLL_STATE_IDLE){                return false;            }            final View pressedView = mPressedView;            BaseViewHolder vh = (BaseViewHolder) recyclerView.getChildViewHolder(pressedView);            if (isHeaderOrFooterPosition(vh.getLayoutPosition())) {                return false;            }            Set
    
      childClickViewIds = vh.getChildClickViewIds();            Set
     
       nestViewIds = vh.getNestViews();            if (childClickViewIds != null && childClickViewIds.size() > 0) {                for (Integer childClickViewId : childClickViewIds) {                    View childView = pressedView.findViewById(childClickViewId);                    if (childView != null) {                        if (inRangeOfView(childView, e) && childView.isEnabled()) {                            if (nestViewIds!=null&&nestViewIds.contains(childClickViewId)){                                return false;                            }                            setPressViewHotSpot(e, childView);                            childView.setPressed(true);                            onItemChildClick(baseQuickAdapter, childView, vh.getLayoutPosition() - baseQuickAdapter.getHeaderLayoutCount());                            resetPressedView(childView);                            return true;                        } else {                            childView.setPressed(false);                        }                    }                }                setPressViewHotSpot(e,pressedView);                mPressedView.setPressed(true);                for (Integer childClickViewId : childClickViewIds) {                    View childView = pressedView.findViewById(childClickViewId);                    if (childView!=null){                        childView.setPressed(false);                    }                }                onItemClick(baseQuickAdapter, pressedView, vh.getLayoutPosition() - baseQuickAdapter.getHeaderLayoutCount());            } else {                setPressViewHotSpot(e,pressedView);                mPressedView.setPressed(true);                if (childClickViewIds != null && childClickViewIds.size() > 0) {                    for (Integer childClickViewId : childClickViewIds) {                        View childView = pressedView.findViewById(childClickViewId);                        if (childView!=null){                            childView.setPressed(false);                        }                    }                }                onItemClick(baseQuickAdapter, pressedView, vh.getLayoutPosition() - baseQuickAdapter.getHeaderLayoutCount());            }            resetPressedView(pressedView);        }        return true;    }    private void resetPressedView(final View pressedView) {        if (pressedView!=null){            pressedView.postDelayed(new Runnable() {                @Override                public void run() {                    if (pressedView!=null){                        pressedView.setPressed(false);                    }                }            }, 100);        }        mIsPrepressed = false;        mPressedView = null;    }    @Override    public void onLongPress(MotionEvent e) {        Log.i(TAG,">>>>onLongPress e"+e);        boolean isChildLongClick =false;        if (recyclerView.getScrollState()!=RecyclerView.SCROLL_STATE_IDLE){            return ;        }        if (mIsPrepressed && mPressedView != null) {            mPressedView.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS);            BaseViewHolder vh = (BaseViewHolder) recyclerView.getChildViewHolder(mPressedView);            if (!isHeaderOrFooterPosition(vh.getLayoutPosition())) {                Set
      
        longClickViewIds = vh.getItemChildLongClickViewIds();                Set
       
         nestViewIds = vh.getNestViews();                if (longClickViewIds != null && longClickViewIds.size() > 0) {                    for (Integer longClickViewId : longClickViewIds) {                        View childView = mPressedView.findViewById(longClickViewId);                        if (inRangeOfView(childView, e) && childView.isEnabled()) {                            if (nestViewIds!=null&&nestViewIds.contains(longClickViewId)){                                isChildLongClick=true;                                break;                            }                            setPressViewHotSpot(e, childView);                            onItemChildLongClick(baseQuickAdapter, childView, vh.getLayoutPosition() - baseQuickAdapter.getHeaderLayoutCount());                            childView.setPressed(true);                            mIsShowPress = true;                            isChildLongClick = true;                            break;                        }                    }                }                if (!isChildLongClick){                    onItemLongClick(baseQuickAdapter, mPressedView, vh.getLayoutPosition() - baseQuickAdapter.getHeaderLayoutCount());                    setPressViewHotSpot(e,mPressedView);                    mPressedView.setPressed(true);                    if (longClickViewIds != null) {                        for (Integer longClickViewId : longClickViewIds) {                            View childView = mPressedView.findViewById(longClickViewId);                            childView.setPressed(false);                        }                    }                    mIsShowPress = true;                }            }        }    }}private void setPressViewHotSpot(final MotionEvent e,final  View mPressedView) {    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {        /**         * when   click   Outside the region  ,mPressedView is null         */        if (mPressedView !=null && mPressedView.getBackground() != null) {            mPressedView.getBackground().setHotspot(e.getRawX(), e.getY()-mPressedView.getY());        }    }}/** * Callback method to be invoked when an item in this AdapterView has * been clicked. * * @param view     The view within the AdapterView that was clicked (this *                 will be a view provided by the adapter) * @param position The position of the view in the adapter. */public abstract void onItemClick(BaseQuickAdapter adapter, View view, int position);/** * callback method to be invoked when an item in this view has been * click and held * * @param view     The view whihin the AbsListView that was clicked * @param position The position of the view int the adapter * @return true if the callback consumed the long click ,false otherwise */public abstract void onItemLongClick(BaseQuickAdapter adapter, View view, int position);public abstract void onItemChildClick(BaseQuickAdapter adapter, View view, int position);public abstract void onItemChildLongClick(BaseQuickAdapter adapter, View view, int position);public boolean inRangeOfView(View view, MotionEvent ev) {    int[] location = new int[2];    if (view==null||!view.isShown()){        return false;    }    view.getLocationOnScreen(location);    int x = location[0];    int y = location[1];    if (ev.getRawX() < x            || ev.getRawX() > (x + view.getWidth())            || ev.getRawY() < y            || ev.getRawY() > (y + view.getHeight())) {        return false;    }    return true;}private boolean isHeaderOrFooterPosition(int position) {    /**     *  have a headview and EMPTY_VIEW FOOTER_VIEW LOADING_VIEW     */    if (baseQuickAdapter==null){        if (recyclerView!=null){            baseQuickAdapter= (BaseQuickAdapter) recyclerView.getAdapter();        }else {            return false;        }    }    int type = baseQuickAdapter.getItemViewType(position);    return (type == EMPTY_VIEW || type == HEADER_VIEW || type == FOOTER_VIEW || type == LOADING_VIEW);}private boolean isHeaderOrFooterView(int type) {    return (type == EMPTY_VIEW || type == HEADER_VIEW || type == FOOTER_VIEW || type == LOADING_VIEW);}}

用过BVAH框架中的点击事件的小伙伴们应该对以下几个接口类不陌生：

  • OnItemChildClickListener 给childView添加点击事件监听器
  • OnItemChildLongClickListener 给childView添加长点击事件监听器
  • OnItemClickListener 给整个Item添加点击事件监听器
  • OnItemLongClickListener 给整个Item添加长点击事件监听器

里面都提供了响应的回调接口，但是赋予他们能力的其实是SimpleClickListener 这个类。是不是开始开兴趣了？让我们一起来看下这个类的真实面目：

public abstract class SimpleClickListener implements RecyclerView.OnItemTouchListener {....}

  • 首先我们发现SimpleClickListener 实现了RecyclerView.OnItemTouchListener 接口OnItemTouchListener接口是recyclerview提供的一个监听item被点击的监听器，源码如下：

    允许应用去拦截处理touch事件，通常实现操作recyclerview 的交互事件时用到public static interface OnItemTouchListener {在onInterceptTouchEvent方法会在recyclerview的childview 发生touch交互前被调用  public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e);  public void onTouchEvent(RecyclerView rv, MotionEvent e);  public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept); }

注：点击事件的实现有多重方式，如：

  • 使用 RecyclerView提供的 addOnItemTouchListener()实现
  • 创建 ItemView时添加点击事件监听
  • 在 ItemView attach RecyclerView时实现

####类内字段解析

  • private GestureDetectorCompat mGestureDetector; 手势检测辅助类，相对于GestureDetectorCompat 有更好的兼容性，且api使用相同。
  • private RecyclerView recyclerView; 存储recyclerview实例对象，后面在获取adapter和viewholder时用到
  • protected BaseQuickAdapter baseQuickAdapter;
  • private boolean mIsPrepressed = false;控件被按下标标识
  • private boolean mIsShowPress = false; 控件press状态标识
  • private View mPressedView = null; 被点击的控件

接下来我们根据事件的传递机制进行分析，当touch事件发生时： onInterceptTouchEvent是第一个被调用的。

@Overridepublic boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {    Log.i(TAG,">>>>onInterceptTouchEvent e"+e.getActionMasked());    if (recyclerView == null) {        this.recyclerView = rv;        this.baseQuickAdapter = (BaseQuickAdapter) recyclerView.getAdapter();        mGestureDetector = new GestureDetectorCompat(recyclerView.getContext(), new ItemTouchHelperGestureListener(recyclerView));    }else if (recyclerView!=rv){        this.recyclerView = rv;        this.baseQuickAdapter = (BaseQuickAdapter) recyclerView.getAdapter();        mGestureDetector = new GestureDetectorCompat(recyclerView.getContext(), new ItemTouchHelperGestureListener(recyclerView));    }    if (!mGestureDetector.onTouchEvent(e) && e.getActionMasked() == MotionEvent.ACTION_UP && mIsShowPress) {        if (mPressedView!=null){            BaseViewHolder vh = (BaseViewHolder) recyclerView.getChildViewHolder(mPressedView);            if (vh == null ||!isHeaderOrFooterView(vh.getItemViewType())) {                mPressedView.setPressed(false);            }        }        mIsShowPress = false;        mIsPrepressed = false;    }    return false;}

源码中，在onInterceptTouchEvent 方法中主要做了两件事情：

  • 初始化recyclerView、baseQuickAdapter、mGestureDetector实例
  • 如果点击事件最终没被消费掉，则恢复被touch而进入press状态中的控件状态。

然后我们就可以在onTouchEvent 方法中将touch事件交给mGestureDetector进行处理了

@Override   public void onTouchEvent(RecyclerView rv, MotionEvent e) {       Log.i(TAG,">>>>onTouchEvent e"+e.getActionMasked());       mGestureDetector.onTouchEvent(e);   }

然后我们看在初始化mGestureDetector时绑定的ItemTouchHelperGestureListener 监听器, ItemTouchHelperGestureListener 监听器继承自SimpleOnGestureListener类，我们进入SimpleOnGestureListener的源码可以看到：

public static class SimpleOnGestureListener implements OnGestureListener, OnDoubleTapListener,        OnContextClickListener {

其内部其实是实现了在个手势交互监听器，只是方法体什么都没做，这样的好处是，我们继承他，可以不用实现一堆方法，需要用到哪个方法，重写该方法就可以了。

我们这次主要用到了如下几个方法：

  • onDown 按下时触发
  • onShowPress 处于press状态时触发
  • onSingleTapUp 单击事件触发
  • onLongPress 长点击事件press状态触发

可以看到，使用GestureDetectorCompat的好处。

根据一个touch事件的发生过程，down->showpress->up 即压下，显示挤压效果，松开弹起。

@Override    public boolean onDown(MotionEvent e) {        mIsPrepressed = true;        mPressedView = recyclerView.findChildViewUnder(e.getX(), e.getY());        super.onDown(e);        return false;    }

在down中：

  • 重置mIsPrepressed 为true，当前已被点击，未松开
  • 根据e的x、y，获得被点击的view。

@Override public void onShowPress(MotionEvent e) { if (mIsPrepressed && mPressedView != null) { mIsShowPress = true; } super.onShowPress(e); } 在showpress中：

  • 根据down的结果，设置mIsShowPress字段，确定当前是否出于showpress状态

如果是单机事件则会触发 onSingleTapUp(MotionEvent e) 在从onSIngleTapUp的源码中可以看到：

if (mIsPrepressed && mPressedView != null) {

  • 如果是我们的recyclerview中的view被点击了才会执行后面的代码

    if (recyclerView.getScrollState()!=RecyclerView.SCROLL_STATE_IDLE){              return false;          }

  • 如果未处于RecyclerView.SCROLL_STATE_IDLE状态直接返回false，此时用户可能是在滑动，没不是点击操作

    final View pressedView = mPressedView;          BaseViewHolder vh = (BaseViewHolder) recyclerView.getChildViewHolder(pressedView);          if (isHeaderOrFooterPosition(vh.getLayoutPosition())) {              return false;          }

  • 获取viewholder 如果是头部视图或者尾部视图，返回false ，我们不需要处理

接下来到了关键代码了：

Set
    
      childClickViewIds = vh.getChildClickViewIds();

  • 获取添加了点击事件的view 的ids Set<Integer> nestViewIds = vh.getNestViews();

  • 获取内嵌了recyclerview的view容器 的ids if (childClickViewIds != null && childClickViewIds.size() > 0) {

  • 如果有view添加了点击事件监听

    for (Integer childClickViewId : childClickViewIds) {

  • 则开始遍历views

    View childView = pressedView.findViewById(childClickViewId);

  • 根据ids获得添加了点击事件的view

    if (inRangeOfView(childView, e) && childView.isEnabled()) {

  • 判断view处于点击范围内切isEnable

如果在点击范围内切isEnable = true则执行下面代码

if (nestViewIds!=null&&nestViewIds.contains(childClickViewId)){                return false;  }
  • 如果是内嵌recyclerview ，则不处理，交由子recyclerview进行处理。

经过层层过滤之后，剩下的就是当view被点击时需要做的操作了： 如果

  • setPressViewHotSpot(e, childView); 修改childview的状态
  • childView.setPressed(true); 设置其press为true
  • onItemChildClick(baseQuickAdapter, childView, vh.getLayoutPosition() - baseQuickAdapter.getHeaderLayoutCount());调用onItemChildClick回调事件。
  • resetPressedView(childView); 重置childview的状态
  • return true; 表示该事件已被消费

如果不出于点击范围内或者isEable=false 则 childView.setPressed(false);

上面处理了item下的childview 的点击，如果是item维度的点击，则执行下面代码，流程基本一致，只是回调的是onItemClick方法。

setPressViewHotSpot(e,pressedView);                mPressedView.setPressed(true);                for (Integer childClickViewId : childClickViewIds) {                    View childView = pressedView.findViewById(childClickViewId);                    if (childView!=null){                        childView.setPressed(false);                    }                }                onItemClick(baseQuickAdapter, pressedView, vh.getLayoutPosition() - baseQuickAdapter.getHeaderLayoutCount());            }

之前处理的是存在childview 的情况，如果不存在childview，自然点击事件都是item的了，操作跟在存在childview但childview不处于点击范围内或者isEable=false时类似。

else {                setPressViewHotSpot(e,pressedView);                mPressedView.setPressed(true);                if (childClickViewIds != null && childClickViewIds.size() > 0) {                    for (Integer childClickViewId : childClickViewIds) {                        View childView = pressedView.findViewById(childClickViewId);                        if (childView!=null){                            childView.setPressed(false);                        }                    }                }                onItemClick(baseQuickAdapter, pressedView, vh.getLayoutPosition() - baseQuickAdapter.getHeaderLayoutCount());            }            resetPressedView(pressedView);

长点击的实现类似，这里就不做重复的分析了。如果大家有哪里不懂的可以直接留言 总结：通过GestureDetectorCompat的使用，能很好的简化我们的编码量，在涉及到交互的操作时，都可以使用GestureDetectorCompat来进行辅助。最好的老师就是阅读优秀的源码，欢迎一起学习，共同进步！

转载于:https://my.oschina.net/zaizaiangels/blog/867358

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