Question

Android onTouchEvent和setOnTouchListener中onTouch的区别

Answer 1

onTouchEvent是用来监听整个屏幕的滚动，setOnTouchListener是监听某个控件的。但setOnTouchListener监听最外层布局的滚动时，他们的就一样了。

Answer 2

在dispatch过程中会先去check已经被set的OnTouchListener，如果在OnTouchListener的onTouch里头return true了，就会直接return true，不再走view本身的onTouchEvent。具体看代码：

/**
* 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 (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(event, 0);
}

if (onFilterTouchEventForSecurity(event)) {
//noinspection SimplifiableIfStatement
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) {
return true;
}

if (onTouchEvent(event)) {
return true;
}
}

if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
}
return false;
}

Talk is cheap, show me the code.