Activity中
當屏幕有touch事件時，首先調用Activity的dispatchTouchEvent方法
/**
* Called to process touch screen events. You can override this to
* intercept all touch screen events before they are dispatched to the
* window. Be sure to call this implementation for touch screen events
* that should be handled normally.
*
* @param ev The touch screen event.
*
* @return boolean Return true if this event was consumed.
*/
public boolean dispatchTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_DOWN) {
onUserInteraction();
}
if (getWindow().superDispatchTouchEvent(ev)) {
return true;
}
return onTouchEvent(ev);
}
首先分析Activity的attach方法可以發現getWindow()返回的就是PhoneWindow對象（PhoneWindow爲抽象Window的實現子類），那就簡單了，也就相當於PhoneWindow類的方法，而PhoneWindow類實現於Window抽象類，所以先看下Window類中抽象方法的定義，如下：
<span style="font-size:24px;">/**
* Used by custom windows, such as Dialog, to pass the touch screen event
* further down the view hierarchy. Application developers should
* not need to implement or call this.
*用戶不需要重寫實現的方法，實質也不能，在Activity中沒有提供重寫的機會，因爲Window是以組</span><pre name="code" class="java"><span style="font-size:24px;">*</span><span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-size:18px;">合模式與Activity建立關係的</span></span>
@Override
public boolean superDispatchTouchEvent(MotionEvent event) {
return mDecor.superDispatchTouchEvent(event);
}
在PhoneWindow類裏發現，mDecor是DecorView類的實例，同時DecorView是PhoneWindow的內部類。最驚人的發現是DecorView extends FrameLayout implements RootViewSurfaceTaker，看見沒有？它是一個真正Activity的root view,它繼承了FrameLayout。
不知道大家是不是熟悉Android App開發技巧中關於UI佈局優化使用的SDK工具Hierarchy Viewer，打開的時候在最上面會有個DecorView$PhoneWindow的框框
Activity中setContentView時，把我們編寫的xmlLayout文件放置在一個id爲content的FrameLayout的佈局（DecorView）中，這也就是爲啥Activity的setContentView方法叫set content view了，就是把我們的xml放入了這個id爲content的FrameLayout中
講完了DecorView，我們在來看看mDecor.superDispatchTouchEvent(event)：
public boolean superDispatchTouchEvent(MotionEvent event) {
return super.dispatchTouchEvent(event);
}
Activity的dispatchTouchEvent方法的if (getWindow().superDispatchTouchEvent(ev))本質執行的是一個ViewGroup的dispatchTouchEvent方法（這個ViewGroup是Activity特有的root view，也就是id爲content的FrameLayout佈局）
在Activity的觸摸屏事件派發中：Activity,PhoneWindow,DecorView,ViewGroup
1,首先會觸發Activity的dispatchTouchEvent方法。
2,dispatchTouchEvent方法中如果是ACTION_DOWN的情況下會接着觸發onUserInteraction方法。
3,接着在dispatchTouchEvent方法中會通過Activity的root View（id爲content的FrameLayout），實質是ViewGroup，通過super.dispatchTouchEvent把touchevent派發給各個activity的子view，也就是我們再Activity.onCreat方法中setContentView時設置的view。
4，若Activity下面的子view攔截了touchevent事件(返回true)則Activity.onTouchEvent方法就不會執行。
ViewGroup中
既然Activity中的DecorView是ViewGroup的子類調用了dispatchTouchEvent方法，來看看這個方法：
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(ev, 1);
}
// If the event targets the accessibility focused view and this is it, start
// normal event dispatch. Maybe a descendant is what will handle the click.
if (ev.isTargetAccessibilityFocus() && isAccessibilityFocusedViewOrHost()) {
ev.setTargetAccessibilityFocus(false);
}
boolean handled = false;
if (onFilterTouchEventForSecurity(ev)) {
final int action = ev.getAction();
final int actionMasked = action & MotionEvent.ACTION_MASK;
/*清除以往的Touch狀態然後開始新的手勢。在這裏你會發現cancelAndClearTouchTargets(ev)方法中有一個非常重要的操作就是將mFirstTouchTarget設置爲了null（剛開始分析大眼瞄一眼沒留意，結果越往下看越迷糊，所以這個是分析ViewGroup的dispatchTouchEvent方法第一步中重點要記住的一個地方），接着在resetTouchState()方法中重置Touch狀態標識。*/
// Handle an initial down.
if (actionMasked == MotionEvent.ACTION_DOWN) {
// Throw away all previous state when starting a new touch gesture.
// The framework may have dropped the up or cancel event for the previous gesture
// due to an app switch, ANR, or some other state change.
cancelAndClearTouchTargets(ev);
resetTouchState();
}
// Check for interception.檢查攔截
final boolean intercepted;
if (actionMasked == MotionEvent.ACTION_DOWN
|| mFirstTouchTarget != null) {// 說明當事件爲ACTION_DOWN或者mFirstTouchTarget不爲null(即已經找到能夠接收touch事件的目標組件)時if成立，否則if不成立，然後將intercepted設置爲true，也即攔截事件
final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;
if (!disallowIntercept) { // 如果沒有禁止攔截，就調用onInterceptTouchEvent方法，touch事件就繼續傳遞給子View，默認不攔截
intercepted = onInterceptTouchEvent(ev);
ev.setAction(action); // restore action in case it was changed存儲動作以防止它改變
} else {
intercepted = false; // 如果禁止攔截，intercepted就是false，touch事件就繼續傳遞給子View
}
} else {
// There are no touch targets and this action is not an initial down
// so this view group continues to intercept touches.如果沒有touch目標組件和down事件，這個viewgroup就是繼續攔截touch
intercepted = true;
}
// If intercepted, start normal event dispatch. Also if there is already
// a view that is handling the gesture, do normal event dispatch.
if (intercepted || mFirstTouchTarget != null) {
ev.setTargetAccessibilityFocus(false);
}
// Check for cancelation.檢查取消，然後將結果賦值給局部boolean變量canceled
final boolean canceled = resetCancelNextUpFlag(this)
|| actionMasked == MotionEvent.ACTION_CANCEL;
// Update list of touch targets for pointer down, if needed. 默認是true，作用是是否把事件分發給多個子View
final boolean split = (mGroupFlags & FLAG_SPLIT_MOTION_EVENTS) != 0;
TouchTarget newTouchTarget = null;
boolean alreadyDispatchedToNewTouchTarget = false;
if (!canceled && !intercepted) { // 如果沒有被取消也沒有被攔截，就開始進行分發事件了
// If the event is targeting accessiiblity focus we give it to the
// view that has accessibility focus and if it does not handle it
// we clear the flag and dispatch the event to all children as usual.
// We are looking up the accessibility focused host to avoid keeping
// state since these events are very rare.
View childWithAccessibilityFocus = ev.isTargetAccessibilityFocus()
? findChildWithAccessibilityFocus() : null;
if (actionMasked == MotionEvent.ACTION_DOWN
|| (split && actionMasked == MotionEvent.ACTION_POINTER_DOWN)
|| actionMasked == MotionEvent.ACTION_HOVER_MOVE) {
final int actionIndex = ev.getActionIndex(); // always 0 for down
final int idBitsToAssign = split ? 1 << ev.getPointerId(actionIndex)
: TouchTarget.ALL_POINTER_IDS;
// Clean up earlier touch targets for this pointer id in case they
// have become out of sync.
removePointersFromTouchTargets(idBitsToAssign);
final int childrenCount = mChildrenCount;
if (newTouchTarget == null && childrenCount != 0) { // childrenCount個數是否不爲0且新的touch target是空，目的就是爲了找到touch target
final float x = ev.getX(actionIndex);
final float y = ev.getY(actionIndex);
// Find a child that can receive the event.
// Scan children from front to back.
final ArrayList<View> preorderedList = buildOrderedChildList();//子View的list集合preorderedList
final boolean customOrder = preorderedList == null
&& isChildrenDrawingOrderEnabled();
final View[] children = mChildren;
for (int i = childrenCount - 1; i >= 0; i--) {//for循環i從childrenCount - 1開始遍歷到0，倒序遍歷所有的子view
final int childIndex = customOrder
? getChildDrawingOrder(childrenCount, i) : i;
final View child = (preorderedList == null)
? children[childIndex] : preorderedList.get(childIndex);
// If there is a view that has accessibility focus we want it
// to get the event first and if not handled we will perform a
// normal dispatch. We may do a double iteration but this is
// safer given the timeframe.
if (childWithAccessibilityFocus != null) {
if (childWithAccessibilityFocus != child) {
continue;
}
childWithAccessibilityFocus = null;
i = childrenCount - 1;
}
if (!canViewReceivePointerEvents(child)
|| !isTransformedTouchPointInView(x, y, child, null)) {
ev.setTargetAccessibilityFocus(false);
continue;
}
newTouchTarget = getTouchTarget(child); //這一句很重要，通過getTouchTarget去查找當前子View是否在mFirstTouchTarget.next這條target鏈中的某一個target中，如果在則返回這個target，否則返回null
if (newTouchTarget != null) {//找到了接收Touch事件的子View，即newTouchTarget，那麼，既然已經找到了，所以執行break跳出for循環
// Child is already receiving touch within its bounds.
// Give it the new pointer in addition to the ones it is handling.
newTouchTarget.pointerIdBits |= idBitsToAssign;
break;
}
resetCancelNextUpFlag(child);
/**
*調用方法dispatchTransformedTouchEvent()將Touch事件傳遞給特定的子View。該方法十分重要，在該方法中爲一個遞歸調用，會遞歸調用 dispatchTouchEvent()方法。在dispatchTouchEvent()中如果子View爲ViewGroup並且Touch沒有被攔截那麼遞歸調用dispatchTouchEvent()，如果子View爲View那麼就會調用其onTouchEvent()。dispatchTransformedTouchEvent方法如果返回true則表示子View消費掉該事件，同時進入該if判斷。滿足if語句後重要的操作有：
1,給newTouchTarget賦值；
2,給alreadyDispatchedToNewTouchTarget賦值爲true；
3,執行break，因爲該for循環遍歷子View判斷哪個子View接受Touch事件，既然已經找到了就跳出該外層for循環；
*/
if (dispatchTransformedTouchEvent(ev, false, child, idBitsToAssign)) {
// Child wants to receive touch within its bounds.
mLastTouchDownTime = ev.getDownTime();
if (preorderedList != null) {
// childIndex points into presorted list, find original index
for (int j = 0; j < childrenCount; j++) {
if (children[childIndex] == mChildren[j]) {
mLastTouchDownIndex = j;
break;
}
}
} else {
mLastTouchDownIndex = childIndex;
}
mLastTouchDownX = ev.getX();
mLastTouchDownY = ev.getY();
newTouchTarget = addTouchTarget(child, idBitsToAssign);
alreadyDispatchedToNewTouchTarget = true;
break;
}
// The accessibility focus didn't handle the event, so clear
// the flag and do a normal dispatch to all children.
ev.setTargetAccessibilityFocus(false);
}
if (preorderedList != null) preorderedList.clear();
}
if (newTouchTarget == null && mFirstTouchTarget != null) {
// Did not find a child to receive the event.
// Assign the pointer to the least recently added target.
newTouchTarget = mFirstTouchTarget;
while (newTouchTarget.next != null) {
newTouchTarget = newTouchTarget.next;
}
newTouchTarget.pointerIdBits |= idBitsToAssign;
}
}
}
/**
*因爲在dispatchTransformedTouchEvent()會調用遞歸調用dispatchTouchEvent()和onTouchEvent()，所以dispatchTransformedTouchEvent()的返回值實際上是由
onTouchEvent()決定的。簡單地說onTouchEvent()是否消費了Touch事件的返回值決定了dispatchTransformedTouchEvent()的返回值，從而決定mFirstTouchTarget是否爲null，進一步決定了ViewGroup 是否處理Touch事件
*/
// Dispatch to touch targets.
if (mFirstTouchTarget == null) {
// No touch targets so treat this as an ordinary view.
handled = dispatchTransformedTouchEvent(ev, canceled, null,
TouchTarget.ALL_POINTER_IDS);
} else {
// Dispatch to touch targets, excluding the new touch target if we already
// dispatched to it. Cancel touch targets if necessary.
TouchTarget predecessor = null;
TouchTarget target = mFirstTouchTarget;
while (target != null) {
final TouchTarget next = target.next;
if (alreadyDispatchedToNewTouchTarget && target == newTouchTarget) {
handled = true;
} else {
final boolean cancelChild = resetCancelNextUpFlag(target.child)
|| intercepted;
if (dispatchTransformedTouchEvent(ev, cancelChild,
target.child, target.pointerIdBits)) {
handled = true;
}
if (cancelChild) {
if (predecessor == null) {
mFirstTouchTarget = next;
} else {
predecessor.next = next;
}
target.recycle();
target = next;
continue;
}
}
predecessor = target;
target = next;
}
}
// Update list of touch targets for pointer up or cancel, if needed.
if (canceled
|| actionMasked == MotionEvent.ACTION_UP
|| actionMasked == MotionEvent.ACTION_HOVER_MOVE) {
resetTouchState();
} else if (split && actionMasked == MotionEvent.ACTION_POINTER_UP) {
final int actionIndex = ev.getActionIndex();
final int idBitsToRemove = 1 << ev.getPointerId(actionIndex);
removePointersFromTouchTargets(idBitsToRemove);
}
}
if (!handled && mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(ev, 1);
}
return handled;
}
ViewGroup中的onInterceptTouchEvent
/**
* Implement this method to intercept all touch screen motion events. This
* allows you to watch events as they are dispatched to your children, and
* take ownership of the current gesture at any point.
*實現這個方法攔截屏幕的所有觸摸事件，這就允許你觀察這些事件被分發給你的孩子，在任何一個點掌控當前手勢
* <p>Using this function takes some care, as it has a fairly complicated
* interaction with {@link View#onTouchEvent(MotionEvent)
* View.onTouchEvent(MotionEvent)}, and using it requires implementing
* that method as well as this one in the correct way. Events will be
* received in the following order:
*使用這個函數要小心，它和View的onTouchEvent有十分複雜的交互，事件能夠按照下列的順序被收到:
* <ol>
* <li> You will receive the down event here.1,你將先收到down事件
* <li> The down event will be handled either by a child of this view
* group, or given to your own onTouchEvent() method to handle; this means
* you should implement onTouchEvent() to return true, so you will
* continue to see the rest of the gesture (instead of looking for
* a parent view to handle it). Also, by returning true from
* onTouchEvent(), you will not receive any following
* events in onInterceptTouchEvent() and all touch processing must
* happen in onTouchEvent() like normal.
* 2，down事件要麼被子View的handle,要麼被這個viewgroup的onTouchEvent方法處理
* <li> For as long as you return false from this function, each following
* event (up to and including the final up) will be delivered first here
* and then to the target's onTouchEvent().
* 3，只要onInterceptTouchEvent返回false，後面的每個事件都會繼續分發到touch target執行target's onTouchEvent()
* <li> If you return true from here, you will not receive any
* following events: the target view will receive the same event but
* with the action {@link MotionEvent#ACTION_CANCEL}, and all further
* events will be delivered to your onTouchEvent() method and no longer
* appear here.
* 4，onInterceptTouchEvent返回true, 交給這個ViewGroup的onTouchEvent處理。
* </ol>
*
* @param ev The motion event being dispatched down the hierarchy.
* @return Return true to steal motion events from the children and have
* them dispatched to this ViewGroup through onTouchEvent().
* The current target will receive an ACTION_CANCEL event, and no further
* messages will be delivered here.
*/
public boolean onInterceptTouchEvent(MotionEvent ev) {
return false;
}
如上就是所有ViewGroup關於觸摸屏事件的傳遞機制源碼分析。具體總結如下：
1,Android事件派發是先傳遞到最頂級的ViewGroup，再由ViewGroup遞歸傳遞到View的。
2,在ViewGroup中可以通過onInterceptTouchEvent方法對事件傳遞進行攔截，3,onInterceptTouchEvent方法
1）返回true 代表不允許事件繼續向子View傳遞，則交給這個ViewGroup的onTouchEvent處理
2）返回false 代表不對事件進行攔截，默認返回false，則交給子View的dispatchTouchEvent方法處理
4,事件傳遞到子view 的 dispatchTouchEvent方法中，通過方法傳遞到當前View的onTouchEvent方法中：
（1）如果返回true，那麼這個事件就會止於該view。
（2）如果返回 false ，那麼這個事件會從這個子view 往上傳遞，而且都是傳遞到父View的onTouchEvent 來接收。
（3）如果傳遞到ViewGroup的 onTouchEvent 也返回 false 的話，則繼續傳遞到Activity的onTouchEvent中，如果還是false,則這個事件就會“消失“；事件向上傳遞到中間的任何onTouchEvent方法中，如果返回true，則事件被消費掉，不會再傳遞。
View中觸摸消息機制：
在Android中你只要觸摸控件首先都會觸發控件的dispatchTouchEvent方法（其實這個方法一般都沒在具體的控件類中，而在他的父類View中），所以我們先來看下View的dispatchTouchEvent方法
View中的觸摸消息機制：
/**
* Pass the touch screen motion event down to the target view, or this
* view if it is the target.
*
* @param event The motion event to be dispatched.
* @return True if the event was handled by the view, false otherwise.
*/
public boolean dispatchTouchEvent(MotionEvent event) {
// If the event should be handled by accessibility focus first.
if (event.isTargetAccessibilityFocus()) {
// We don't have focus or no virtual descendant has it, do not handle the event.
if (!isAccessibilityFocusedViewOrHost()) {
return false;
}
// We have focus and got the event, then use normal event dispatch.
event.setTargetAccessibilityFocus(false);
}
boolean result = false;
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(event, 0);
}
final int actionMasked = event.getActionMasked();
if (actionMasked == MotionEvent.ACTION_DOWN) {
// Defensive cleanup for new gesture
stopNestedScroll();
}
if (onFilterTouchEventForSecurity(event)) { // 判斷當前View是否沒被遮住
//noinspection SimplifiableIfStatement ListenerInfo局部變量，ListenerInfo是View的靜態內部類，用來定義一堆關於View的XXXListener等方法
ListenerInfo li = mListenerInfo;
/**一,首先判斷是不是設置onTouch監聽器，onTouch的返回值
* 首先li對象自然不會爲null, li.mOnTouchListener是不是null取決於控件（View）是否設置setOnTouchListener監聽
* 接着通過位與運算確定控件（View）是不是ENABLED 的，默認控件都是ENABLED 的
* 接着判斷onTouch的返回值是不是true
*/
if (li != null && li.mOnTouchListener != null
&& (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) {
result = true; //如果設置了onTouchListener，並且onTouch返回時true，result就是true，下一句if就不執行了，onTouchEvent和onClick就不執行了
}
//上面的執行了result等於true，這句就不執行了。如果result是false，就執行onTouchEvent，onTouchEvent中有執行onClick的步驟
if (!result && onTouchEvent(event)) {
result = true;
}
}
if (!result && mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
}
// Clean up after nested scrolls if this is the end of a gesture;
// also cancel it if we tried an ACTION_DOWN but we didn't want the rest
// of the gesture.
if (actionMasked == MotionEvent.ACTION_UP ||
actionMasked == MotionEvent.ACTION_CANCEL ||
(actionMasked == MotionEvent.ACTION_DOWN && !result)) {
stopNestedScroll();
}
return result;
}
if (li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED && li.mOnTouchListener.onTouch(this, event))if (!result && onTouchEvent(event))控件觸摸就會調運dispatchTouchEvent方法，而在dispatchTouchEvent中先執行的是onTouch方法，所以驗證了實例結論總結中的onTouch優先於onClick執行道理。如果控件是ENABLE且在onTouch方法裏返回了true則dispatchTouchEvent方法也返回true，不會再繼續往下執行；
反之，onTouch返回false則會繼續向下執行onTouchEvent方法，且dispatchTouchEvent的返回值與onTouchEvent返回值相同。
所以依據這個結論和上面實例打印結果你指定已經大膽猜測認爲onClick一定與onTouchEvent有關係？
總結結論
在View的觸摸屏傳遞機制中通過分析dispatchTouchEvent方法源碼我們會得出如下基本結論：
1，觸摸控件（View）首先執行dispatchTouchEvent方法。
2，在dispatchTouchEvent方法中先執行onTouch方法，後執行onClick方法（onClick方法在onTouchEvent中執行，下面會分析）。
3，如果控件（View）的onTouch返回false或者mOnTouchListener爲null（控件沒有設置setOnTouchListener方法）或者控件不是enable的情況下會調運onTouchEvent，dispatchTouchEvent返回值與onTouchEvent返回一樣。
4，如果控件不是enable的設置了onTouch方法也不會執行，只能通過重寫控件的onTouchEvent方法處理（上面已經處理分析了），dispatchTouchEvent返回值與onTouchEvent返回一樣。
5，如果控件（View）是enable且onTouch返回true情況下，dispatchTouchEvent直接返回true，不會調用onTouchEvent方法。
View的dispatchTouchEvent方法中調運的onTouchEvent方法
/**
* Implement this method to handle touch screen motion events.
* <p>
* If this method is used to detect click actions, it is recommended that
* the actions be performed by implementing and calling
* {@link #performClick()}. This will ensure consistent system behavior,
* including:
* <ul>
* <li>obeying click sound preferences
* <li>dispatching OnClickListener calls
* <li>handling {@link AccessibilityNodeInfo#ACTION_CLICK ACTION_CLICK} when
* accessibility features are enabled
* </ul>
*
* @param event The motion event.
* @return True if the event was handled, false otherwise.
*/
public boolean onTouchEvent(MotionEvent event) {
final float x = event.getX();
final float y = event.getY();
final int viewFlags = mViewFlags;
if ((viewFlags & ENABLED_MASK) == DISABLED) { // 組件設置的disabled，組件不可用，那就直接返回了
if (event.getAction() == MotionEvent.ACTION_UP && (mPrivateFlags & PFLAG_PRESSED) != 0) {
setPressed(false);
}
// A disabled view that is clickable still consumes the touch
// events, it just doesn't respond to them.
return (((viewFlags & CLICKABLE) == CLICKABLE ||
(viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE));
}
if (mTouchDelegate != null) {
if (mTouchDelegate.onTouchEvent(event)) {
return true;
}
}
if (((viewFlags & CLICKABLE) == CLICKABLE ||
(viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE)) { //如果組件是enabled且可點擊，或者可長點擊
switch (event.getAction()) {
case MotionEvent.ACTION_UP:
boolean prepressed = (mPrivateFlags & PFLAG_PREPRESSED) != 0;
if ((mPrivateFlags & PFLAG_PRESSED) != 0 || prepressed) {
// take focus if we don't have it already and we should in
// touch mode.
// 首先判斷了是否按下過，同時是不是可以得到焦點，然後嘗試獲取焦點，然後判斷如果不是longPressed則通過post在UI Thread中執行一個PerformClick的Runnable，也就是performClick方法。
boolean focusTaken = false;
if (isFocusable() && isFocusableInTouchMode() && !isFocused()) {
focusTaken = requestFocus();
}
if (prepressed) {
// The button is being released before we actually
// showed it as pressed. Make it show the pressed
// state now (before scheduling the click) to ensure
// the user sees it.
setPressed(true, x, y);
}
if (!mHasPerformedLongPress) {
// This is a tap, so remove the longpress check
removeLongPressCallback();
// Only perform take click actions if we were in the pressed state
if (!focusTaken) {
// Use a Runnable and post this rather than calling
// performClick directly. This lets other visual state
// of the view update before click actions start.
// 使用post一個Runnable的PerformClick的任務類而不是直接調用performClick的方法。
if (mPerformClick == null) {
mPerformClick = new PerformClick();
}
if (!post(mPerformClick)) {
performClick();// 終於找到了，onClick方法在performClick的函數中
}
}
}
if (mUnsetPressedState == null) {
mUnsetPressedState = new UnsetPressedState();
}
if (prepressed) {
postDelayed(mUnsetPressedState,
ViewConfiguration.getPressedStateDuration());
} else if (!post(mUnsetPressedState)) {
// If the post failed, unpress right now
mUnsetPressedState.run();
}
removeTapCallback();
}
break;
// ACTION_DOWN與ACTION_MOVE都進行了一些必要的設置與置位
case MotionEvent.ACTION_DOWN:
mHasPerformedLongPress = false;
if (performButtonActionOnTouchDown(event)) {
break;
}
// Walk up the hierarchy to determine if we're inside a scrolling container.
boolean isInScrollingContainer = isInScrollingContainer();
// For views inside a scrolling container, delay the pressed feedback for
// a short period in case this is a scroll.
if (isInScrollingContainer) {
mPrivateFlags |= PFLAG_PREPRESSED;
if (mPendingCheckForTap == null) {
mPendingCheckForTap = new CheckForTap();
}
mPendingCheckForTap.x = event.getX();
mPendingCheckForTap.y = event.getY();
postDelayed(mPendingCheckForTap, ViewConfiguration.getTapTimeout());
} else {
// Not inside a scrolling container, so show the feedback right away
setPressed(true, x, y);
checkForLongClick(0);
}
break;
case MotionEvent.ACTION_CANCEL:
setPressed(false);
removeTapCallback();
removeLongPressCallback();
break;
case MotionEvent.ACTION_MOVE:
drawableHotspotChanged(x, y);
// Be lenient about moving outside of buttons
if (!pointInView(x, y, mTouchSlop)) {
// Outside button
removeTapCallback();
if ((mPrivateFlags & PFLAG_PRESSED) != 0) {
// Remove any future long press/tap checks
removeLongPressCallback();
setPressed(false);
}
}
break;
}
return true;
}
return false;
}
<span style="font-size:24px;">/**
* Call this view's OnClickListener, if it is defined. Performs all normal
* actions associated with clicking: reporting accessibility event, playing
* a sound, etc.
*調用這個view的OnClickListener方法。
* @return True there was an assigned OnClickListener that was called, false
* otherwise is returned.
*/
public boolean performClick() {
final boolean result;
final ListenerInfo li = mListenerInfo;
if (li != null && li.mOnClickListener != null) { // 和dispatchTouchEvent中的判斷一樣，li自然不是null,如果設置了OnclickListener那麼 li.mOnClickListener也不爲空
playSoundEffect(SoundEffectConstants.CLICK);
li.mOnClickListener.onClick(this); // 這個是重點！！！！！，執行這個View的Onclick方法，返回true
result = true;
} else {
result = false;
}
sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
return result;
}
</span>猜的沒錯onClick就在onTouchEvent中執行的，而且是在onTouchEvent的ACTION_UP事件中執行的
總結結論
1，onTouchEvent方法中會在ACTION_UP分支中觸發onClick的監聽。
2，當dispatchTouchEvent在進行事件分發的時候，只有前一個action返回true，纔會觸發下一個action。
參考：http://blog.csdn.net/yanbober/article/details/45887547