事件傳遞

2019-11-09 17:53:34

字體：大中小

來源：轉載

供稿：網友

//ViewGroup的事件處理 @Override public boolean dispatchTouchEvent(MotionEvent event) { boolean consume = false; if (onInterceptTouchEvent(event)) {//ViewGroup攔截（viewgroup默認不攔截） consume = onTouchEvent(event);//則ViewGroup處理事件 } else {//ViewGroup不攔截 consume = child.dispatchTouchEvent(event);//則子view派發事件 } return consume; }

事件的傳遞：隧道式派發

先執行dispatchTouchEvent方法 再執行onInterceptTouchEvent方法（view無此方法） true，攔截，不用派發給下級 false，不攔截，派發給下級

事件的處理：冒泡式消費

只執行onTouchEvent方法（view沒有攔截方法，事件傳遞過來時一定會執行這個方法，當clickable和longclickable都為true時如button默認消費事件） true，處理了，不用處理了 false，沒處理，給上級處理

dispatchTouchEvent方法：事件傳遞到當前view，此方法一定會被調用，返回值受當前view的onTouchEvent和下級view的dispatchTouchEvent返回值影響。

最后一級view一定會調用onTouchEvent方法。

例子如下：

Markdown

MyView

public class MyView extends View { //處理事件 @Override public boolean onTouchEvent(MotionEvent event) { Log.e("TouchEvent","MyView==onTouchEvent=="+super.onTouchEvent(event)+"==" +event.getAction()+"=="+System.currentTimeMillis()); return super.onTouchEvent(event); } //派發事件 @Override public boolean dispatchTouchEvent(MotionEvent ev) { Log.e("TouchEvent","MyView==dispatchTouchEvent=="+super.onTouchEvent(ev)+"==" +ev.getAction()+"=="+System.currentTimeMillis()); return super.dispatchTouchEvent(ev); } public MyView(Context context) { super(context); } public MyView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } public MyView(Context context, AttributeSet attrs) { super(context, attrs); }}

ViewGroupA

public class ViewGroupA extends LinearLayout { //處理事件 @Override public boolean onTouchEvent(MotionEvent event) { Log.e("TouchEvent","ViewGroupA==onTouchEvent=="+super.onTouchEvent(event)+"==" +event.getAction()+"=="+System.currentTimeMillis()); return super.onTouchEvent(event); } //派發事件 @Override public boolean dispatchTouchEvent(MotionEvent ev) { Log.e("TouchEvent","ViewGroupA==dispatchTouchEvent=="+super.onTouchEvent(ev)+"==" +ev.getAction()+"=="+System.currentTimeMillis()); return super.dispatchTouchEvent(ev); } //攔截事件 @Override public boolean onInterceptTouchEvent(MotionEvent ev) { Log.e("TouchEvent","ViewGroupA==onInterceptTouchEvent=="+super.onTouchEvent(ev)+"==" +ev.getAction()+"=="+System.currentTimeMillis()); return super.onInterceptTouchEvent(ev); } //構造方法 public ViewGroupA(Context context) { super(context); } public ViewGroupA(Context context, AttributeSet attrs) { super(context, attrs); } public ViewGroupA(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); }}

ViewGroupB

public class ViewGroupB extends LinearLayout { //處理事件 @Override public boolean onTouchEvent(MotionEvent event) { Log.e("TouchEvent","ViewGroupB==onTouchEvent=="+super.onTouchEvent(event)+"==" +event.getAction()+"=="+System.currentTimeMillis()); return super.onTouchEvent(event); } //派發事件 @Override public boolean dispatchTouchEvent(MotionEvent ev) { Log.e("TouchEvent","ViewGroupB==dispatchTouchEvent=="+super.onTouchEvent(ev)+"==" +ev.getAction()+"=="+System.currentTimeMillis()); return super.dispatchTouchEvent(ev); } //攔截事件 @Override public boolean onInterceptTouchEvent(MotionEvent ev) { Log.e("TouchEvent","ViewGroupB==onInterceptTouchEvent=="+super.onTouchEvent(ev)+"==" +ev.getAction()+"=="+System.currentTimeMillis()); return super.onInterceptTouchEvent(ev); } public ViewGroupB(Context context) { super(context); } public ViewGroupB(Context context, AttributeSet attrs) { super(context, attrs); } public ViewGroupB(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); }}

布局：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.administrator.myapplication.MainActivity"> <com.example.administrator.myapplication.ViewGroupA android:layout_width="match_parent" android:layout_height="match_parent" android:background="@android:color/holo_blue_bright"> <com.example.administrator.myapplication.ViewGroupB android:layout_width="300dp" android:layout_height="300dp" android:background="@android:color/holo_green_dark"> <com.example.administrator.myapplication.MyView android:layout_width="150dp" android:layout_height="150dp" android:background="@android:color/darker_gray" /> </com.example.administrator.myapplication.ViewGroupB> </com.example.administrator.myapplication.ViewGroupA></RelativeLayout>

點擊ViewGroupA

02-06 11:48:55.295 10298-10298/? E/TouchEvent: ViewGroupA==dispatchTouchEvent==false==0==148635293529502-06 11:48:55.295 10298-10298/? E/TouchEvent: ViewGroupA==onInterceptTouchEvent==false==0==148635293529502-06 11:48:55.295 10298-10298/? E/TouchEvent: ViewGroupA==onTouchEvent==false==0==1486352935295

點擊ViewGroupB

02-06 11:47:40.835 10298-10298/? E/TouchEvent: ViewGroupA==dispatchTouchEvent==false==0==148635286083402-06 11:47:40.835 10298-10298/? E/TouchEvent: ViewGroupA==onInterceptTouchEvent==false==0==148635286083502-06 11:47:40.835 10298-10298/? E/TouchEvent: ViewGroupB==dispatchTouchEvent==false==0==148635286083502-06 11:47:40.835 10298-10298/? E/TouchEvent: ViewGroupB==onInterceptTouchEvent==false==0==148635286083502-06 11:47:40.835 10298-10298/? E/TouchEvent: ViewGroupB==onTouchEvent==false==0==148635286083502-06 11:47:40.835 10298-10298/? E/TouchEvent: ViewGroupA==onTouchEvent==false==0==1486352860835

點擊MyView

02-06 11:45:01.557 10298-10298/? E/TouchEvent: ViewGroupA==dispatchTouchEvent==false==0==148635270155602-06 11:45:01.557 10298-10298/? E/TouchEvent: ViewGroupA==onInterceptTouchEvent==false==0==148635270155702-06 11:45:01.557 10298-10298/? E/TouchEvent: ViewGroupB==dispatchTouchEvent==false==0==148635270155702-06 11:45:01.557 10298-10298/? E/TouchEvent: ViewGroupB==onInterceptTouchEvent==false==0==148635270155702-06 11:45:01.557 10298-10298/? E/TouchEvent:MyView==dispatchTouchEvent==false==0==148635270155702-06 11:45:01.557 10298-10298/? E/TouchEvent: MyView==onTouchEvent==false==0==148635270155702-06 11:45:01.562 10298-10298/? E/TouchEvent:ViewGroupB==onTouchEvent==false==0==148635270156202-06 11:45:01.562 10298-10298/? E/TouchEvent: ViewGroupA==onTouchEvent==false==0==1486352701562