【移動應(yīng)用開發(fā)技術(shù)】Android中怎么實現(xiàn)觸摸事件傳遞機制

【移動應(yīng)用開發(fā)技術(shù)】Android中怎么實現(xiàn)觸摸事件傳遞機制

這篇文章給大家介紹Android中怎么實現(xiàn)觸摸事件傳遞機制，內(nèi)容非常詳細，感興趣的小伙伴們可以參考借鑒，希望對大家能有所幫助。一.觸摸事件的類型觸摸事件對應(yīng)的是MotionEvent類，事件類型主要有三種：ACTION_DOWN：用戶按下操作，表示一次觸摸事件的開始。ACTION_MOVE：在按下的情況下，進行移動。輕微的移動都會傳遞到該事件。ACTION_UP：用戶手指離開屏幕，表示一次觸摸事件的注：如果用戶僅僅的是點擊而已，則只會執(zhí)行到ACTION_DOWN和ACTION_UP兩個事件，不會執(zhí)行到ACTION_MOVE事件。所以ACTION_DOWN和ACTION_UP是事件是必須的。二.觸摸事件的傳遞階段1.分發(fā)（Dispatch）在Android系統(tǒng)中所有的觸摸事件都是由dispatchTouchEvent方法進行分發(fā)的。該方法中判斷事件是被消費（returntrue），還是繼續(xù)分發(fā)給子視圖處理（returnsuper.dispatchTouchEvent），如果當(dāng)前視圖是ViewGroup或者其子類，則會調(diào)用onInterceptTouchEvent判斷是否截攔。@Override

public

boolean

dispatchTouchEvent(MotionEvent

event)

{

return

super.dispatchTouchEvent(event);

}2.截攔（Intercept）事件的截攔InterceptTouchEvent只存在于ViewGroup及其子類，activity和View是不存在該方法。該方法判斷事件是被截攔（returntrue）并交給自身的OnToucEvent方法進行消費，還是繼續(xù)傳遞給子視圖（returnsuper.InterceptTouchEvent或者returnfalse）。@Override

public

boolean

onInterceptTouchEvent(MotionEvent

ev)

{

return

super.onInterceptTouchEvent(ev);

}3.消費（Consume）事件的消費通過OnTouchEvent方法判斷，是被消費（returntrue）,還是不處理（returnfalse）并將事件傳遞給父視圖的OnTouchEvent方法進行處理。@Override

public

boolean

onTouchEvent(MotionEvent

event)

{

return

super.onTouchEvent(event);

}所有擁有事件傳遞能力的類：Activity：擁有dispatchTouchEvent、OnTouchEventViewGroup：擁有dispatchTouchEvent、OnInterceptTouchEvent、OnTouchEventView：擁有dispatchTouchEvent、OnTouchEvent三、View的事件傳遞機制3.1dome雖然說ViewGroup是View的子類，但是這是說的View指的是除ViewGroup之外的View控件子類，首先定義一個MyTextView繼承TextView，打印每次事件的觸發(fā)以變了解事件傳遞的流程。MyTextView類public

class

MyTextView

extends

TextView

{

private

String

tag

=

"MyTextView";

public

MyTextView(Context

context)

{

super(context);

}

public

MyTextView(Context

context,

AttributeSet

attrs)

{

super(context,

attrs);

}

@Override

public

boolean

dispatchTouchEvent(MotionEvent

event)

{

switch

(event.getAction()){

case

MotionEvent.ACTION_UP:

Log.i(tag,

"dispatchTouchEvent

ACTION_UP");

break;

case

MotionEvent.ACTION_MOVE:

Log.i(tag,

"dispatchTouchEvent

ACTION_MOVE");

break;

case

MotionEvent.ACTION_DOWN:

Log.i(tag,

"dispatchTouchEvent

ACTION_DOWN");

break;

}

return

super.dispatchTouchEvent(event);

}

@Override

public

boolean

onTouchEvent(MotionEvent

event)

{

switch

(event.getAction()){

case

MotionEvent.ACTION_UP:

Log.i(tag,

"onTouchEvent

ACTION_UP");

break;

case

MotionEvent.ACTION_MOVE:

Log.i(tag,

"onTouchEvent

ACTION_MOVE");

break;

case

MotionEvent.ACTION_DOWN:

Log.i(tag,

"onTouchEvent

ACTION_DOWN");

break;

}

return

super.onTouchEvent(event);

}

}定義一個MainActivity來展現(xiàn)這個MyTextView，同時設(shè)置點擊（onClick）和觸摸（onTouch）監(jiān)聽。MainActivity類public

class

MainActivity

extends

AppCompatActivity

implements

View.OnClickListener,View.OnTouchListener{

private

MyTextView

mMyTextView;

private

String

tag

=

"MainActiviy";

@Override

protected

void

onCreate(Bundle

savedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

mMyTextView

=

findViewById(R.id.text_view);

//

點擊監(jiān)聽

mMyTextView.setOnClickListener(this);

//

觸碰監(jiān)聽

mMyTextView.setOnTouchListener(this);

}

//

MyTextView

點擊事件

@Override

public

void

onClick(View

view)

{

switch

(view.getId()){

case

R.id.text_view:

Log.i(tag,

"MyTextView

onClick");

break;

}

}

//

MyTextView

觸碰事件

@Override

public

boolean

onTouch(View

view,

MotionEvent

motionEvent)

{

switch

(motionEvent.getAction()){

case

MotionEvent.ACTION_UP:

Log.i(tag,

"MyTextView

onTouch

ACTION_UP");

break;

case

MotionEvent.ACTION_MOVE:

Log.i(tag,

"MyTextView

onTouch

ACTION_MOVE");

break;

case

MotionEvent.ACTION_DOWN:

Log.i(tag,

"MyTextView

onTouch

ACTION_DOWN");

break;

}

return

false;

}

//

Activity?的事件分發(fā)

@Override

public

boolean

dispatchTouchEvent(MotionEvent

ev)

{

switch

(ev.getAction()){

case

MotionEvent.ACTION_UP:

Log.i(tag,

"dispatchTouchEvent

ACTION_UP");

break;

case

MotionEvent.ACTION_MOVE:

Log.i(tag,

"dispatchTouchEvent

ACTION_MOVE");

break;

case

MotionEvent.ACTION_DOWN:

Log.i(tag,

"dispatchTouchEvent

ACTION_DOWN");

break;

}

return

super.dispatchTouchEvent(ev);

}

//

Activity

的事件消費

@Override

public

boolean

onTouchEvent(MotionEvent

event)

{

switch

(event.getAction()){

case

MotionEvent.ACTION_UP:

Log.i(tag,

"onTouchEvent

ACTION_UP");

break;

case

MotionEvent.ACTION_MOVE:

Log.i(tag,

"onTouchEvent

ACTION_MOVE");

break;

case

MotionEvent.ACTION_DOWN:

Log.i(tag,

"onTouchEvent

ACTION_DOWN");

break;

}

return

super.onTouchEvent(event);

}

}3.2打印日志運行后，點擊TextView反饋的打印日志03-2808:05:14.8241219-1219/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:dispatchTouchEventACTION_DOWN03-2808:05:14.8241219-1219/com.mvp.chenzhesheng.androidadvanceI/MyTextView:dispatchTouchEventACTION_DOWN03-2808:05:14.8241219-1219/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:MyTextViewonTouchACTION_DOWN03-2808:05:14.8241219-1219/com.mvp.chenzhesheng.androidadvanceI/MyTextView:onTouchEventACTION_DOWN03-2808:05:15.0341219-1219/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:dispatchTouchEventACTION_UP03-2808:05:15.0341219-1219/com.mvp.chenzhesheng.androidadvanceI/MyTextView:dispatchTouchEventACTION_UP03-2808:05:15.0341219-1219/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:MyTextViewonTouchACTION_UP03-2808:05:15.0341219-1219/com.mvp.chenzhesheng.androidadvanceI/MyTextView:onTouchEventACTION_UP03-2808:05:15.0441219-1219/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:MyTextViewonClick03-2808:05:14.8241219-1219/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:dispatchTouchEventACTION_DOWN03-2808:05:14.8241219-1219/com.mvp.chenzhesheng.androidadvanceI/MyTextView:dispatchTouchEventACTION_DOWN03-2808:05:14.8241219-1219/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:MyTextViewonTouchACTION_DOWN03-2808:05:14.8241219-1219/com.mvp.chenzhesheng.androidadvanceI/MyTextView:onTouchEventACTION_DOWN03-2808:05:15.0341219-1219/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:dispatchTouchEventACTION_UP03-2808:05:15.0341219-1219/com.mvp.chenzhesheng.androidadvanceI/MyTextView:dispatchTouchEventACTION_UP03-2808:05:15.0341219-1219/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:MyTextViewonTouchACTION_UP03-2808:05:15.0341219-1219/com.mvp.chenzhesheng.androidadvanceI/MyTextView:onTouchEventACTION_UP03-2808:05:15.0441219-1219/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:MyTextViewonClickdispatchTouchEvent、OnTouchEvent這兩個方法的返回值存在三種情況：直接返回true。直接返回false。返回父類同名方法，super.dispatchTouchEvent或者super.OnTouchEvent。由于擁有不同的返回值，所以事件傳遞流程也有不同，經(jīng)過不斷修改返回值測試，最終得到了點擊事件的流程圖，ACTION_DOWN和ACTION_UP事件的傳遞流程是相同的。3.3事件傳遞流程圖從上面的流程圖可以得出結(jié)論：觸摸事件是從dispatchTouchEvent開始的，默認返回父類同名方法super，事件將會依照嵌套層次從外向內(nèi)傳遞（MainActivity到MyTextView），到達最內(nèi)層的View時，將由View的OnTouchEvent方法處理，該方法返回true時進行消費不再傳遞，返回false時再由內(nèi)向外傳遞，由外層的OnTouchEvent處理。如果外層向內(nèi)層傳遞過程中，人為干擾返回true消費，則不會繼續(xù)繼續(xù)像內(nèi)部傳遞。View的事件控制順序先執(zhí)行onTouch再執(zhí)行onClick，如果onTouch返回true消費，則不會繼續(xù)傳遞，也不會執(zhí)行onClick方法。四、ViewGroup的事件傳遞機制4.1domeViewGroup是View的控件容器存在，擁有dispatchTouchEvent、onInterceptTouchEvent和onTouchEvent三個方法，比View多了一個onInterceptTouchEvent方法。為了更好的觀察，我們需要自定義MyRelativeLayout繼承RelativeLayout。MyRelativeLayout類public

class

MyRelativeLayout

extends

RelativeLayout

{

private

final

static

String

tag

=

"MyRelativeLayout";

public

MyRelativeLayout(Context

context)

{

super(context);

}

public

MyRelativeLayout(Context

context,

AttributeSet

attrs)

{

super(context,

attrs);

}

@Override

public

boolean

dispatchTouchEvent(MotionEvent

ev)

{

switch

(ev.getAction()){

case

MotionEvent.ACTION_UP:

Log.i(tag,

"dispatchTouchEvent

ACTION_UP");

break;

case

MotionEvent.ACTION_MOVE:

Log.i(tag,

"dispatchTouchEvent

ACTION_MOVE");

break;

case

MotionEvent.ACTION_DOWN:

Log.i(tag,

"dispatchTouchEvent

ACTION_DOWN");

break;

}

return

super.dispatchTouchEvent(ev);

}

@Override

public

boolean

onInterceptTouchEvent(MotionEvent

ev)

{

switch

(ev.getAction()){

case

MotionEvent.ACTION_UP:

Log.i(tag,

"onInterceptTouchEvent

ACTION_UP");

break;

case

MotionEvent.ACTION_MOVE:

Log.i(tag,

"onInterceptTouchEvent

ACTION_MOVE");

break;

case

MotionEvent.ACTION_DOWN:

Log.i(tag,

"onInterceptTouchEvent

ACTION_DOWN");

break;

}

return

super.onInterceptTouchEvent(ev);

}

@Override

public

boolean

onTouchEvent(MotionEvent

event)

{

switch

(event.getAction()){

case

MotionEvent.ACTION_UP:

Log.i(tag,

"onTouchEvent

ACTION_UP");

break;

case

MotionEvent.ACTION_MOVE:

Log.i(tag,

"onTouchEvent

ACTION_MOVE");

break;

case

MotionEvent.ACTION_DOWN:

Log.i(tag,

"onTouchEvent

ACTION_DOWN");

break;

}

return

super.onTouchEvent(event);

}

}main_activity.xml文件<?xml

version="1.0"

encoding="utf-8"?>

<com.mvp.chenzhesheng.androidadvance.MyRelativeLayout

xmlns:android="/apk/res/android"

xmlns:tools="/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

>

<com.mvp.chenzhesheng.androidadvance.MyTextView

android:id="@+id/text_view"

android:clickable="true"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="Hello

World!"

</com.mvp.chenzhesheng.androidadvance.MyRelativeLayout>4.2打印日志04-0208:47:57.9801030-1030/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:dispatchTouchEventACTION_DOWN04-0208:47:58.0001030-1030/com.mvp.chenzhesheng.androidadvanceI/MyRelativeLayout:dispatchTouchEventACTION_DOWN04-0208:47:58.0001030-1030/com.mvp.chenzhesheng.androidadvanceI/MyRelativeLayout:onInterceptTouchEventACTION_DOWN04-0208:47:58.0001030-1030/com.mvp.chenzhesheng.androidadvanceI/MyTextView:dispatchTouchEventACTION_DOWN04-0208:47:58.0101030-1030/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:MyTextViewonTouchACTION_DOWN04-0208:47:58.0101030-1030/com.mvp.chenzhesheng.androidadvanceI/MyTextView:onTouchEventACTION_DOWN04-0208:47:58.2001030-1030/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:dispatchTouchEventACTION_UP04-0208:47:58.2001030-1030/com.mvp.chenzhesheng.androidadvanceI/MyRelativeLayout:dispatchTouchEventACTION_UP04-0208:47:58.2001030-1030/com.mvp.chenzhesheng.androidadvanceI/MyRelativeLayout:onInterceptTouchEventACTION_UP04-0208:47:58.2001030-1030/com.mvp.chenzhesheng.androidadvanceI/MyTextView:dispatchTouchEventACTION_UP04-0208:47:58.2101030-1030/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:MyTextViewonTouchACTION_UP04-0208:47:58.2101030-1030/com.mvp.chenzhesheng.androidadvanceI/MyTextView:onTouchEventACTION_UP04-0208:47:58.2601030-1030/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:MyTextViewonClick04-0208:47:57.9801030-1030/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:dispatchTouchEventACTION_DOWN04-0208:47:58.0001030-1030/com.mvp.chenzhesheng.androidadvanceI/MyRelativeLayout:dispatchTouchEventACTION_DOWN04-0208:47:58.0001030-1030/com.mvp.chenzhesheng.androidadvanceI/MyRelativeLayout:onInterceptTouchEventACTION_DOWN04-0208:47:58.0001030-1030/com.mvp.chenzhesheng.androidadvanceI/MyTextView:dispatchTouchEventACTION_DOWN04-0208:47:58.0101030-1030/com.mvp.chenzhesheng.androidadvanceI/MainActiviy:MyTextViewonTouchACTION_DOWN04-0208:47:58.