BaseRecyclerViewAdapterHelper开源项目之点击事件源码学习

摘要: BaseRecyclerViewAdapterHelper开源项目之点击事件源码学习

##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<Integer> childClickViewIds = vh.getChildClickViewIds();
Set<Integer> 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<Integer> longClickViewIds = vh.getItemChildLongClickViewIds();
Set<Integer> 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。

@Override
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;
}

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<Integer> 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);
3ff0
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！