2015-11-26 17:00:22
前言：Android的Touch事件传递和View的实现紧密相连，因此理解Touch事件的传递，有助于我们更好的理解View的工作原理。
1. 几个重要的方法：
View.java
=============
dispatchTouchEvent():用来分发、传递Touch事件，如果Touch事件被当前View处理了，就返回true，否则返回false。
/**
* Pass the touch screen motion event down to the target view, or this
* view if it is the target.
* 将Touch事件传递到目标View，如果自己就是目标View的话，就给自己
* @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)) {
//noinspection SimplifiableIfStatement
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnTouchListener != null
&& (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) { (1)
result = true;
} if (!result && onTouchEvent(event)) { (2)
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;
}
通俗理解：
该方法是View上Touch事件传递的第一道防线，现在只需要记住：
(1)处代码调用了OnTouchListener，如果你给当前View设置了setOnTouchListener()，那么，此处会被调用；
(2)如果你设置的onTouchListener的onTouch方法，返回的是false，那么此处有机会调用当前View的onTouchEvent方法。如果返回true，不会调用onTouchEvent，同时你设置的onClickListener也不会得到调用，这点我们接下来分析。
onTouchEvent()：当前View收到Touch事件后，真正使用Touch事件的地方。
public boolean onTouchEvent(MotionEvent event) {
final float x = event.getX();
final float y = event.getY();
final int viewFlags = mViewFlags;
if ((viewFlags & ENABLED_MASK) == DISABLED) {
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)) {
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.
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.
if (mPerformClick == null) {
mPerformClick = new PerformClick();
}
if (!post(mPerformClick)) {
performClick(); （1）
}
}
}
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;
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); （2）
}
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;
}
在onTouchEvent()方法中，分别处理不同类型的Touch事件。注意：
(1)当前View处理Click事件的地方，没错，就是在MotionEvent.Action_UP的时候处理的；
(2)当前View处理LongClick事件的地方，在MotionEvent.Action_DOWN的时候处理的；
ViewGroup.java
=============
ViewGroup是继承自View的，当然也继承了上面那两个方法。ViewGroup不仅是一个View，也是一个可以拥有Children View的View Container，所以它重写了dispatchTouchEvent()方法，但是没有重写onTouchEvent()方法。同时，ViewGroup觉得自己好歹是个Container，得有点特权嘛，所以给自己搞了个onInterceptTouchEvent()方法，如下：
public boolean dispatchTouchEvent(MotionEvent ev) {
boolean handled = false;
if (onFilterTouchEventForSecurity(ev)) {
final int action = ev.getAction();
final int actionMasked = action & MotionEvent.ACTION_MASK;
// 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.
final boolean intercepted;
if (actionMasked == MotionEvent.ACTION_DOWN
|| mFirstTouchTarget != null) {
final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;
if (!disallowIntercept) {
intercepted = onInterceptTouchEvent(ev); (1)
ev.setAction(action); // restore action in case it was changed
} else {
intercepted = false;
}
} else {
// There are no touch targets and this action is not an initial down
// so this view group continues to intercept touches.
intercepted = true;
}
// Check for cancelation.
final boolean canceled = resetCancelNextUpFlag(this)
|| actionMasked == MotionEvent.ACTION_CANCEL;
// Update list of touch targets for pointer down, if needed.
final boolean split = (mGroupFlags & FLAG_SPLIT_MOTION_EVENTS) != 0;
TouchTarget newTouchTarget = null;
boolean alreadyDispatchedToNewTouchTarget = false;
if (!canceled && !intercepted) { (2)
……
}
ViewGroup的dispatchTouchView()方法，加了一些自己的判断，最终调用的仍然是View中的dispatchTouchView()，先关注一下红色代码:
(1)ViewGroup调用了自己的onInterceptTouchEvent();
(2)只有onInterceptTouchEvent()返回false时，才会继续执行下面的代码。这里可以这么理解，onInterceptTouchEvent()返回true，表示该Touch事件被拦截，不会向Children View传递，分发给自己handle，如果返回false，才会继续向Children View传递。
onInterceptTouchEvent(MotionEvent ev)：
/* @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;
}
此方法默认返回false。
2. 写个小Demo，源码如下：
MyLinear1.java
public class MyLinear1 extends LinearLayout {
public MyLinear1(Context context) {
super(context);
}
public MyLinear1(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyLinear1(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
}
boolean isDispatch = true;
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
Log.e("David--MyLinear", "dispatchTouchEvent-" + getS(ev.getAction()));
if (isDispatch) {
boolean one = super.dispatchTouchEvent(ev);
Log.e("David--MyLinear", "dispatchTouchEvent() super.dispatchTouchEvent(event) = " + one);
return one;
} else {
return true;
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
Log.e("David--MyLinear", "onTouchEvent-" + getS(event.getAction()));
return true;
}
public static String getS(int action) {
String ret = "null";
switch (action) {
case MotionEvent.ACTION_CANCEL:
ret = "Cancel";
break;
case MotionEvent.ACTION_DOWN:
ret = "Down";
break;
case MotionEvent.ACTION_MOVE:
ret = "Move";
break;
case MotionEvent.ACTION_UP:
ret = "Up";
break;
}
return ret;
}
}
继承自LinearLayout，重写了那几个方法。
CustomView.java
public class CustomView extends View {
private Paint mPaint;
public CustomView(Context context) {
super(context);
mPaint = new Paint();
mPaint.setColor(Color.RED);
}
public CustomView(Context context, AttributeSet attrs) {
super(context, attrs);
mPaint = new Paint();
mPaint.setColor(Color.RED);
}
public CustomView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mPaint = new Paint();
mPaint.setColor(Color.RED);
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
//canvas.drawLine(0, 0, 100, 400, mPaint);
canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint);
mPaint.setColor(Color.GREEN);
canvas.drawText("我是文字", 30, 45, mPaint);
canvas.restore();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
//super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getContext().getResources().getDisplayMetrics().widthPixels, 400);
}
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
Log.e("David--C---------------", "dispatchTouchEvent-" + MyLinear1.getS(event.getAction()));
boolean one = super.dispatchTouchEvent(event);
Log.e("David--C---------------", "dispatchTouchEvent() super.dispatchTouchEvent(event) = " + one);
return one;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
Log.e("David--C---------------", "onTouchEvent-" + MyLinear1.getS(event.getAction()));
return false;
}
}
这是一个简单地View。
布局文件：当前页面的根View可以认为是MyLinear1，里面只包含了一个子CustomView。至于Activity的根View，我们后续再分析。
<?xml version="1.0" encoding="utf-8"?>
<com.meituan.david.myapplication.MyLinear1 xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/linear"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<com.meituan.david.myapplication.CustomView
android:layout_width="match_parent"
android:layout_height="200dp" />
</com.meituan.david.myapplication.MyLinear1>
上日志：
前提：MyLinear1的onInterceptTouchEvent()方法返回true，意味着Touch事件不会向Children View传递，所以CustomView的两个方法的返回值无所谓了~
11-30 18:12:01.014 E/David--MyLinear(20933): dispatchTouchEvent-Down
11-30 18:12:02.139 E/David--MyLinear(20933): dispatchTouchEvent-Down
11-30 18:12:03.004 E/David--MyLinear(20933): dispatchTouchEvent-Down
触摸(点击、滑动)操作三次打出的log，事件根本没有传递到子View，并且，由于自己MyLinear1不想处理Touch事件，所以只收到了ACTION_DOWN,此后的Touch事件不会再传入了；
2. MyLinear1的dispatchTouchEvent()方法返回false，onTouchEvent返回true，日志如下：
日志和1是一样的，很明显，如果MyLinear1的dispatchTouchEvent()直接返回false，无论其他方法的返回值如何，说明当前ViewGroup不想处理Touch事件，所有后续的Touch事件不会再传入了。
3. MyLinear1的dispatchTouchEvent()方法返回true，onTouchEvent返回false，日志如下：
11-30 18:26:38.451 E/David--MyLinear( 8268): dispatchTouchEvent-Down
11-30 18:26:38.592 E/David--MyLinear( 8268): dispatchTouchEvent-Move
11-30 18:26:38.608 E/David--MyLinear( 8268): dispatchTouchEvent-Move
11-30 18:26:38.625 E/David--MyLinear( 8268): dispatchTouchEvent-Move
11-30 18:26:38.798 E/David--MyLinear( 8268): dispatchTouchEvent-Up
MyLinear1的dispatchTouchEvent()直接返回true，Touch事件源源不断的传入，但是onInterceptTouchEvent()和onTouchEvent()并没有被调用。
根据以上三点，我们可以得出一个结论：
MyLinear1的dispatchTouchEvent()方法，会接受"系统"(暂且认为是系统吧)传入的Touch事件，如果直接返回false，则系统不会再传入Touch事件；返回true，会继续传入。但是，由于没有调用super.dispatchTouchEvent()方法，此Touch事件既不会被拦截/分发，也不会被处理(onInterceptTouchEvent()和onTouchEvent()不会被调用)~
4. MyLinear1的dispatchTouchEvent()方法返回super.dispatchTouchEvent()，onTouchEvent返回false，日志如下：
11-30 18:56:04.757 E/David--MyLinear( 8156): dispatchTouchEvent-Down
11-30 18:56:04.758 E/David--MyLinear( 8156): onInterceptTouchEvent-Down
11-30 18:56:04.758 E/David--MyLinear( 8156): onTouchEvent-Down
11-30 18:56:04.758 E/David--MyLinear( 8156): dispatchTouchEvent() super.dispatchTouchEvent(event) = false
另外两个方法得到了调用，但是由于onTouchEvent返回false，说明MyLinear1不想处理后续的Touch事件，所以后续的Touch事件没有传入。仔细看，此时的super.dispatchTouchEvent(event) = false，这也解释了为什么只传入了ACTION_DOWN事件。
5. MyLinear1的dispatchTouchEvent()方法返回super.dispatchTouchEvent()，onTouchEvent返回true，日志如下：
11-30 19:02:18.189 E/David--MyLinear(11377): dispatchTouchEvent-Down
11-30 19:02:18.189 E/David--MyLinear(11377): onInterceptTouchEvent-Down
11-30 19:02:18.189 E/David--MyLinear(11377): onTouchEvent-Down
11-30 19:02:18.476 E/David--MyLinear(11377): dispatchTouchEvent() super.dispatchTouchEvent(event)-true 11-30 19:02:18.505 E/David--MyLinear(11377): dispatchTouchEvent-Move
11-30 19:02:18.505 E/David--MyLinear(11377): onTouchEvent-Move
11-30 19:02:18.505 E/David--MyLinear(11377): dispatchTouchEvent() super.dispatchTouchEvent(event)-true 11-30 19:02:18.505 E/David--MyLinear(11377): dispatchTouchEvent-Up
11-30 19:02:18.505 E/David--MyLinear(11377): onTouchEvent-Up
11-30 19:02:18.505 E/David--MyLinear(11377): dispatchTouchEvent() super.dispatchTouchEvent(event)-true
现在onTouchEvent返回true，说明他愿意处理Touch事件，所以就源源不断的传入了，同时super.dispatchTouchEvent(event)=true，接受系统传入的Touch事件~同时呢，如果当前View决定处理=Touch事件，那么后续传入的Touch事件，就不需要onInterceptTouchEvent了....
根据4、5，我们可以得出一个结论：
dispatchTouchEvent()的返回值和onTouchEvent()的返回值是息息相关的，所以diapatchTouchEvent方法不调用super.dispatchTouchEvent()是没有任何意义的。
以上都是在onInterceptTouchEvent()方法返回true的情况下做的测试，Touch事件根本就没有传递到Children View，那么我们看看onInterceptTouchEvent()方法返回false时，会有什么样的结果。
前提：MyLinear1的dispatchTouchEvent()方法返回super.dispatchTouchEvent()，onInterceptTouchEvent()方法返回false，表示不拦截Touch事件
1. CustomView的dispatchTouchEvent()返回super.dispatchTouchEvent，onTouchEvent返回false，MyLinear1的onTouchEvent返回true，日志如下：
11-30 19:19:54.430 E/David--MyLinear( 1860): dispatchTouchEvent-Down
11-30 19:19:54.430 E/David--MyLinear( 1860): onInterceptTouchEvent-Down
11-30 19:19:54.430 E/David--C---------------( 1860): dispatchTouchEvent-Down
11-30 19:19:54.430 E/David--C---------------( 1860): onTouchEvent-Down
11-30 19:19:54.430 E/David--C---------------( 1860): dispatchTouchEvent() super.dispatchTouchEvent(event) = false
11-30 19:19:54.430 E/David--MyLinear( 1860): onTouchEvent-Down 11-30 19:19:54.659 E/David--MyLinear( 1860): dispatchTouchEvent() super.dispatchTouchEvent(event) = true
11-30 19:19:54.680 E/David--MyLinear( 1860): dispatchTouchEvent-Move
11-30 19:19:54.680 E/David--MyLinear( 1860): onTouchEvent-Move
11-30 19:19:54.680 E/David--MyLinear( 1860): dispatchTouchEvent() super.dispatchTouchEvent(event) = true
11-30 19:19:54.794 E/David--MyLinear( 1860): dispatchTouchEvent-Move
11-30 19:19:54.794 E/David--MyLinear( 1860): onTouchEvent-Move 11-30 19:19:54.794 E/David--MyLinear( 1860): dispatchTouchEvent() super.dispatchTouchEvent(event) = true
11-30 19:19:54.825 E/David--MyLinear( 1860): dispatchTouchEvent-Up
11-30 19:19:54.825 E/David--MyLinear( 1860): onTouchEvent-Up
11-30 19:19:54.825 E/David--MyLinear( 1860): dispatchTouchEvent() super.dispatchTouchEvent(event) = true
事件顺利的传到Custom View，但是由于CustomView的onTouchEvent返回false，意味着他不想处理后续Touch事件，所以，CustomView的dispatchTouchEvent()返回false，Touch事件不再传入到CustomView。那么传入的ACTION_DOWN和后续的Touch事件怎么办呢，总不能没人管吧？其实，当Child View不想处理ACTION_DOWN事件时，ACTION_DOWN就会被回传至Father View，很显然，CustomView的父View就是MyLinear1了，所以MyLinear1的onTouchEvent收到了该事件。如果MyLinear的onTouchEvent决定处理Touch事件，那么就会消化ACTION_DOWN事件，同时后续的Touch事件会源源不断的传给MyLienar1，与CustomView就没有半毛钱关系了~日志也是这么显示的。
2. 和1一样的条件，如果MyLinear1不愿意处理Touch事件呢?onTouchEvent()返回false，我们看日志：
11-30 19:28:42.199 E/David--MyLinear(11273): dispatchTouchEvent-Down
11-30 19:28:42.199 E/David--MyLinear(11273): onInterceptTouchEvent-Down
11-30 19:28:42.199 E/David--C---------------(11273): dispatchTouchEvent-Down
11-30 19:28:42.199 E/David--C---------------(11273): onTouchEvent-Down
11-30 19:28:42.199 E/David--C---------------(11273): dispatchTouchEvent() super.dispatchTouchEvent(event) = false
11-30 19:28:42.199 E/David--MyLinear(11273): onTouchEvent-Down
11-30 19:28:42.199 E/David--MyLinear(11273): dispatchTouchEvent() super.dispatchTouchEvent(event) = false
CustomView不愿处理的Touch事件被回传至MyLinear1，这没问题，但是MyLinear1也不愿意处理Touch事件，所以onTouchEvent返回false，同时super.dispatchTouchEvent(event)返回false，后续的Touch事件就不会再传入了~
3. CustomView的dispatchTouchEvent()返回super.dispatchTouchEvent，onTouchEvent返回true，MyLinear1的onTouchEvent返回false，日志如下：
12-01 12:00:30.735 E/David--MyLinear( 363): dispatchTouchEvent-Down
12-01 12:00:30.735 E/David--MyLinear( 363): onInterceptTouchEvent-Down
12-01 12:00:30.735 E/David--C---------------( 363): dispatchTouchEvent-Down
12-01 12:00:30.735 E/David--C---------------( 363): onTouchEvent-Down
12-01 12:00:30.735 E/David--C---------------( 363): dispatchTouchEvent() super.dispatchTouchEvent(event) = true
12-01 12:00:30.735 E/David--MyLinear( 363): dispatchTouchEvent() super.dispatchTouchEvent(event) = true 12-01 12:00:30.958 E/David--MyLinear( 363): dispatchTouchEvent-Move
12-01 12:00:30.958 E/David--MyLinear( 363): onInterceptTouchEvent-Move
12-01 12:00:30.958 E/David--C---------------( 363): dispatchTouchEvent-Move
12-01 12:00:30.958 E/David--C---------------( 363): onTouchEvent-Move
12-01 12:00:30.958 E/David--C---------------( 363): dispatchTouchEvent() super.dispatchTouchEvent(event) = true
12-01 12:00:30.958 E/David--MyLinear( 363): dispatchTouchEvent() super.dispatchTouchEvent(event) = true 12-01 12:00:30.974 E/David--MyLinear( 363): dispatchTouchEvent-Move
12-01 12:00:30.974 E/David--MyLinear( 363): onInterceptTouchEvent-Move
12-01 12:00:30.974 E/David--C---------------( 363): dispatchTouchEvent-Move
12-01 12:00:30.974 E/David--C---------------( 363): onTouchEvent-Move
12-01 12:00:30.974 E/David--C---------------( 363): dispatchTouchEvent() super.dispatchTouchEvent(event) = true
12-01 12:00:30.974 E/David--MyLinear( 363): dispatchTouchEvent() super.dispatchTouchEvent(event) = true 12-01 12:00:30.992 E/David--MyLinear( 363): dispatchTouchEvent-Move
12-01 12:00:30.992 E/David--MyLinear( 363): onInterceptTouchEvent-Move
12-01 12:00:30.992 E/David--C---------------( 363): dispatchTouchEvent-Move
12-01 12:00:30.992 E/David--C---------------( 363): onTouchEvent-Move
12-01 12:00:30.992 E/David--C---------------( 363): dispatchTouchEvent() super.dispatchTouchEvent(event) = true
12-01 12:00:30.992 E/David--MyLinear( 363): dispatchTouchEvent() super.dispatchTouchEvent(event) = true 12-01 12:00:31.026 E/David--MyLinear( 363): dispatchTouchEvent-Up
12-01 12:00:31.026 E/David--MyLinear( 363): onInterceptTouchEvent-Up
12-01 12:00:31.026 E/David--C---------------( 363): dispatchTouchEvent-Up
12-01 12:00:31.026 E/David--C---------------( 363): onTouchEvent-Up
12-01 12:00:31.026 E/David--C---------------( 363): dispatchTouchEvent() super.dispatchTouchEvent(event) = true
12-01 12:00:31.026 E/David--MyLinear( 363): dispatchTouchEvent() super.dispatchTouchEvent(event) = true
CustomView收到Touch事件，而且想处理它，onTouchEvent返回true，此时Touch事件会源源不断地传至CustomView，CustomView和MyLinear1的dispatchTouchEvent都返回true~有两个新特点：
1、MyLinear1的onInterceptTouchEvent每次都会被调用，这说明，如果ViewGroup决定自己处理Touch事件，那么ACTION_DOWN之后的事件都不会经过onInterceptTouchEvent。但是Children View就不一样了，每次都得被拦截一下，谁让你是Children呢~
2、一旦Children View开始处理Touch事件，就没有MyLinear1的onTouchEvent什么事了。
本文总结：
经过上面的分析，应该是说清楚了dispatchTouchEvent()、onInterceptTouchEvent()和onTouchEvent()方法的使用情况了，记住，这三个方法的调用是有顺序的。对于简单的自定义View或者ViewGroup的需求，应该已经能满足需求了。毕竟，最好是不要直接完全重写dispatchTouchEvent或者onTouchEvent，可以适当的加一些判断，但是最终还是要调用View的方法的，这已经能满足绝大多数的需求了。下一篇，咱们仔细研究一下dispatchTouchEvent()和onTouchEvent()方法的代码