setOnTouchListener onTouchEvent setOnLongClickListener setOnClickListener 执行顺序及源码分析

1.先说 setOnClickListener   setOnTouchListener   onTouchEvent 

1. 1先看运行结果  ：

  MyViewGroup-->dispatchTouchEvent-->ACTION_DOWN

MyViewGroup-->onInterceptTouchEvent-->ACTION_DOWN

MyButton-->dispatchTouchEvent-->ACTION_DOWN

MyButton-->setOnTouchListener-->ACTION_DOWN

MyButton-->onTouchEvent-->ACTION_DOWN

MyViewGroup-->dispatchTouchEvent-->ACTION_UP

MyViewGroup-->onInterceptTouchEvent-->ACTION_UP

MyButton-->dispatchTouchEvent-->ACTION_UP

setOnTouchListener-->ACTION_UP

MyButton-->onTouchEvent-->ACTION_UP

MyButton-->setOnClickListener

1.2 源码分析

   1.先看setOnLongClickListener方法

public void setOnLongClickListener(@Nullable OnLongClickListener l) {
    if (!isLongClickable()) {
        setLongClickable(true);
    }
    getListenerInfo().mOnLongClickListener = l;
}

public interface OnLongClickListener {
  
    boolean onLongClick(View v);
}

看到我们实例化的接口赋值给了mOnLongClickListener  ，好这就够了，如果好奇getListenerInfo()，自己可以去了解下。

 2.再看 setOnClickListener

public void setOnClickListener(@Nullable OnClickListener l) {
    if (!isClickable()) {
        setClickable(true);
    }
    getListenerInfo().mOnClickListener = l;
}

其实和setOnLongClickListener差不多 知道mOnClickListener 就行了。

3. setOnTouchListener

public void setOnTouchListener(OnTouchListener l) {
    getListenerInfo().mOnTouchListener = l;
}

public interface OnTouchListener {
    boolean onTouch(View v, MotionEvent event);
}

注意onTouch 是有返回值的，这点很重要。

4.再来看下 先从 MyButton-->dispatchTouchEvent 开始分析

  

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)) {
        if ((mViewFlags & ENABLED_MASK) == ENABLED && handleScrollBarDragging(event)) {
            result = true;
        }
        //noinspection SimplifiableIfStatement
        // 这里是重点，当我们执行mOnTouchListener.onTouch 监听的 setOnTouchListener 的onTouch 返回值为true 时 result 赋值为true ,这里先执行了setOnTouchListener  方法
        ListenerInfo li = mListenerInfo;
        if (li != null && li.mOnTouchListener != null
                && (mViewFlags & ENABLED_MASK) == ENABLED
                && li.mOnTouchListener.onTouch(this, event)) {
            result = true;
        }
       //当 result 为true是 onTouchEvent 就不会执行了，这就是我上边说的，返回值很重要，监听的setOnTouchListener 消耗掉了本次事件，onTouchEvent不会执行，那么setOnClickListener呢，当然就不会执行了，我们分析下onTouchEvent(event)就知道了。
        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;
}

5.onTouchEvent(event) 与 setOnClickListener 执行关系

onTouchEvent(event)源码分析 

public boolean onTouchEvent(MotionEvent event) {
    final float x = event.getX();
    final float y = event.getY();
    final int viewFlags = mViewFlags;
    final int action = event.getAction();

    if ((viewFlags & ENABLED_MASK) == DISABLED) {
        if (action == 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)
                || (viewFlags & CONTEXT_CLICKABLE) == CONTEXT_CLICKABLE);
    }
    if (mTouchDelegate != null) {
        if (mTouchDelegate.onTouchEvent(event)) {
            return true;
        }
    }

    if (((viewFlags & CLICKABLE) == CLICKABLE ||
            (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE) ||
            (viewFlags & CONTEXT_CLICKABLE) == CONTEXT_CLICKABLE) {
        switch (action) {
            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.
                    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 && !mIgnoreNextUpEvent) {
                        // 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.
                            if (mPerformClick == null) {
                                mPerformClick = new PerformClick();
                            }
                            if (!post(mPerformClick)) {
                            //点击事件在这里执行
                                performClick();
                            }
                        }
                    }

                    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();
                }
                mIgnoreNextUpEvent = false;
                break;

            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, x, y);
                }
                break;

            case MotionEvent.ACTION_CANCEL:
                setPressed(false);
                removeTapCallback();
                removeLongPressCallback();
                mInContextButtonPress = false;
                mHasPerformedLongPress = false;
                mIgnoreNextUpEvent = false;
                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;
}

接着看

performClick() 的实现方式

public boolean performClick() {
    final boolean result;
    final ListenerInfo li = mListenerInfo;
    if (li != null && li.mOnClickListener != null) {
        playSoundEffect(SoundEffectConstants.CLICK);
        li.mOnClickListener.onClick(this);
        result = true;
    } else {
        result = false;
    }

    sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
    return result;
}

在这里我们终于找到了mOnClickListener.onClick   方法，现在我们应该知道这几个之间的关系了吧。

总结：最先执行setOnTouchListener  然后执行onTouchEvet  紧接着在onTouchEvet中执行了setOnClickListener ,当然如果setOnTouchtListener 返回了true 那么后边两部就都不会执行了。

2. setOnLongClickListener setOnTouchListener   onTouchEvent 

2.1执行顺序 结果

11-16 15:03:15.699 20721-20721/com.example.macbook.demoproject2 I/System.out: ------>MyViewGroup-->dispatchTouchEvent-->ACTION_DOWN
11-16 15:03:15.699 20721-20721/com.example.macbook.demoproject2 I/System.out: ------>MyViewGroup-->onInterceptTouchEvent-->ACTION_DOWN
11-16 15:03:15.699 20721-20721/com.example.macbook.demoproject2 I/System.out: ------>MyButton-->dispatchTouchEvent-->ACTION_DOWN
11-16 15:03:15.699 20721-20721/com.example.macbook.demoproject2 I/System.out: MainActivity-->setOnTouchListener-->ACTION_DOWN
11-16 15:03:15.699 20721-20721/com.example.macbook.demoproject2 I/System.out: ------>MyButton-->onTouchEvent-->ACTION_DOWN
11-16 15:03:16.200 20721-20721/com.example.macbook.demoproject2 I/System.out: MainActivityonLongClick: setOnLongClickListener
11-16 15:03:16.996 20721-20721/com.example.macbook.demoproject2 I/System.out: ------>MyViewGroup-->dispatchTouchEvent-->ACTION_UP
11-16 15:03:16.996 20721-20721/com.example.macbook.demoproject2 I/System.out: ------>MyViewGroup-->onInterceptTouchEvent-->ACTION_UP
11-16 15:03:16.996 20721-20721/com.example.macbook.demoproject2 I/System.out: ------>MyButton-->dispatchTouchEvent-->ACTION_UP
11-16 15:03:16.997 20721-20721/com.example.macbook.demoproject2 I/System.out: MainActivity-->setOnTouchListener-->ACTION_UP
11-16 15:03:16.997 20721-20721/com.example.macbook.demoproject2 I/System.out: ------>MyButton-->onTouchEvent-->ACTION_UP

这次我把详细的log粘出来了，先看两个节点时间

1. MyViewGroup-->dispatchTouchEvent-->ACTION_DOWN 到  setOnLongClickListener

11-16 15:03:15.699   -----------------》 11-16 15:03:16.200 从按下到触发长按事件的时间

2.setOnLongClickListener  到  MyViewGroup-->dispatchTouchEvent-->ACTION_UP

11-16 15:03:16.200 ----------------------》11-16 15:03:16.996 这个是触发长按事件到我手指抬起触发父类的第一个方法时间

2.2 源码分析

 在分析之前先有几个问题

    1.长按事件到底啥时执行，按下后多久执行。

    2.触发后为啥我的点击事件没有了。

从MyButton-->onTouchEvent   ACTION_DOWN 开始分析

public boolean onTouchEvent(MotionEvent event) {
    final float x = event.getX();
    final float y = event.getY();
    final int viewFlags = mViewFlags;
    final int action = event.getAction();

    if ((viewFlags & ENABLED_MASK) == DISABLED) {
        if (action == 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)
                || (viewFlags & CONTEXT_CLICKABLE) == CONTEXT_CLICKABLE);
    }
    if (mTouchDelegate != null) {
        if (mTouchDelegate.onTouchEvent(event)) {
            return true;
        }
    }

    if (((viewFlags & CLICKABLE) == CLICKABLE ||
            (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE) ||
            (viewFlags & CONTEXT_CLICKABLE) == CONTEXT_CLICKABLE) {
        switch (action) {
            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.
                    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 && !mIgnoreNextUpEvent) {
                        // 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.
                            if (mPerformClick == null) {
                                mPerformClick = new PerformClick();
                            }
                            if (!post(mPerformClick)) {
                                //点击事件在这里执行
                                performClick();
                            }
                        }
                    }

                    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();
                }
                mIgnoreNextUpEvent = false;
                break;

            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);
                    //这里就是长按事件
                    checkForLongClick(0, x, y);
                }
                break;

            case MotionEvent.ACTION_CANCEL:
                setPressed(false);
                removeTapCallback();
                removeLongPressCallback();
                mInContextButtonPress = false;
                mHasPerformedLongPress = false;
                mIgnoreNextUpEvent = false;
                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;
}

我们在 ACTION_DOWN  中看到checkForLongClick(0, x, y)方法  传入三个参数0，和x,y,接着看checkForLongClick方法

private void checkForLongClick(int delayOffset, float x, float y) {
    if ((mViewFlags & LONG_CLICKABLE) == LONG_CLICKABLE) {
        mHasPerformedLongPress = false;

        if (mPendingCheckForLongPress == null) {
            mPendingCheckForLongPress = new CheckForLongPress();
        }
        mPendingCheckForLongPress.setAnchor(x, y);
        mPendingCheckForLongPress.rememberWindowAttachCount();
        postDelayed(mPendingCheckForLongPress,
                ViewConfiguration.getLongPressTimeout() - delayOffset);
    }
}

CheckForLongPress 实现了 Runnable  接口，然后通过

postDelayed发送消息

public boolean postDelayed(Runnable action, long delayMillis) {
    final AttachInfo attachInfo = mAttachInfo;
    if (attachInfo != null) {
        return attachInfo.mHandler.postDelayed(action, delayMillis);
    }

    // Postpone the runnable until we know on which thread it needs to run.
    // Assume that the runnable will be successfully placed after attach.
    getRunQueue().postDelayed(action, delayMillis);
    return true;
}

其实最后调用了handler 的postDelayed间隔 delayMillis 秒后发送消息，执行Runnable中的run方法，那我们看

Runnable中是如何实现的。

private final class CheckForLongPress implements Runnable {
    private int mOriginalWindowAttachCount;
    private float mX;
    private float mY;

    @Override
    public void run() {
        if (isPressed() && (mParent != null)
                && mOriginalWindowAttachCount == mWindowAttachCount) {
            if (performLongClick(mX, mY)) {
                mHasPerformedLongPress = true;
            }
        }
    }

    public void setAnchor(float x, float y) {
        mX = x;
        mY = y;
    }

    public void rememberWindowAttachCount() {
        mOriginalWindowAttachCount = mWindowAttachCount;
    }
}

看到调用了

performLongClick(mX, mY)方法并且， mHasPerformedLongPress = true;

再看performLongClick 干了啥呢

public boolean performLongClick() {
    return performLongClickInternal(mLongClickX, mLongClickY);
}

private boolean performLongClickInternal(float x, float y) {
    sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_LONG_CLICKED);

    boolean handled = false;
    final ListenerInfo li = mListenerInfo;
    if (li != null && li.mOnLongClickListener != null) {
        handled = li.mOnLongClickListener.onLongClick(View.this);
    }
    if (!handled) {
        final boolean isAnchored = !Float.isNaN(x) && !Float.isNaN(y);
        handled = isAnchored ? showContextMenu(x, y) : showContextMenu();
    }
    if (handled) {
        performHapticFeedback(HapticFeedbackConstants.LONG_PRESS);
    }
    return handled;
}

到这里终于看到了，li.mOnLongClickListener.onLongClick(View.this) 长按事件响应了，过程是有点曲折不过流程算是走完了。总结下，先从view 的

dispatchTouchEvent 然后调用了 view 的 onTouchEvent 事件，然后在ontoucheEvent的action_down中调用

checkForLongClick方法既长按事件。

回到先前提的两个问题

问题1： 长按事件到底啥时执行我们已经知道了，但是按下后多久执行呢？

接着看：

触发checkForLongClick(0, x, y);时传进来第一个参数int类型的，字面意思是，延迟位移，

postDelayed(mPendingCheckForLongPress,
        ViewConfiguration.getLongPressTimeout() - delayOffset);

接着调用 postDelayed 其实后边的 ViewConfiguration.getLongPressTimeout() - delayOffset 就是handler发送消息延迟时间，现在偏移时间为0，那我们只要知道ViewConfiguration.getLongPressTimeout() 是多少就可以了。

public static int getLongPressTimeout() {
    return AppGlobals.getIntCoreSetting(Settings.Secure.LONG_PRESS_TIMEOUT,
            DEFAULT_LONG_PRESS_TIMEOUT);
}

private static final int DEFAULT_LONG_PRESS_TIMEOUT = 500;

默认的长按按压时间是500毫秒，现在再看我开始打log时打出的开始到触发长按，时间基本就是500了。

问题2：为啥点击事件不执行了

我们看到

MyButton-->onTouchEvent-->ACTION_UP

MyButton-->setOnClickListener

点击事件其实是整个事件最后执行的在onTouchEvent 的ACTION_UP 后才执行了，那分析下点击事件的触发条件。

if (!mHasPerformedLongPress && !mIgnoreNextUpEvent) {
    // 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.
        if (mPerformClick == null) {
            mPerformClick = new PerformClick();
        }
        if (!post(mPerformClick)) {
            //点击事件在这里执行
            performClick();
        }
    }
}

mHasPerformedLongPress 这个好像在哪里看到过啊，是的，就在Runnable 方法的run方法里

@Override
public void run() {
    if (isPressed() && (mParent != null)
            && mOriginalWindowAttachCount == mWindowAttachCount) {
        if (performLongClick(mX, mY)) {
            mHasPerformedLongPress = true;
        }
    }
}

由于长按事件先执行，触发了条件， mHasPerformedLongPress = true 所以当事件执行到action_up 时条件不满足了。这就是为啥有长按事件后点击事件不会执行。