Android touchEvent事件传递

来源：互联网发布：有没有淘宝内部优惠券编辑：程序博客网时间：2024/04/30 17:17

网上介绍touchevent事件非常多，这里通过一个简单的Demo来描述事件的传递和拦截过程。
请参考：http://www.cnblogs.com/sunzn/archive/2013/05/10/3064129.html

先介绍touch event相关的知识点。

一个最简单的屏幕触摸动作触发了一系列Touch事件：ACTION_DOWN->ACTION_MOVE->ACTION_MOVE->ACTION_MOVE…->ACTION_MOVE->ACTION_UP

android系统中的每个View以及它的子类都具有下面两个和TouchEvent处理密切相关的方法：

public boolean dispatchTouchEvent(MotionEvent ev) 这个方法用来分发TouchEvent
public boolean onTouchEvent(MotionEvent ev) 这个方法用来处理TouchEvent

而每个ViewGroup以及它的子类都具有下面三个和TouchEvent处理密切相关的方法：

public boolean dispatchTouchEvent(MotionEvent ev) 这个方法用来分发TouchEvent
public boolean onInterceptTouchEvent(MotionEvent ev) 这个方法用来拦截TouchEvent
public boolean onTouchEvent(MotionEvent ev) 这个方法用来处理TouchEvent

当TouchEvent发生时， TouchEvent最先到达最顶层 view 的 dispatchTouchEvent ，然后由 dispatchTouchEvent 方法进行分发，首先交给这个 view 的 interceptTouchEvent 方法来决定是否要拦截这个事件，如果 interceptTouchEvent 返回 true ，也就是拦截掉了，则交给它的 onTouchEvent 来处理，如果 interceptTouchEvent 返回 false ，那么就传递给子 view ，由子 view 的 dispatchTouchEvent 再来开始这个事件的分发。如果事件传递到某一层的子 view 的 onTouchEvent 上了，这个方法返回了 false ，那么这个事件会从这个 view 往上传递，都是 onTouchEvent 来接收。而如果传递到最上面的 onTouchEvent 也返回 false 的话，这个事件就会“消失”，而且接收不到下一次事件。

注意：Ｖiew及其子类不存在onInterceptTouchEvent方法。

源码分析请参考：
Android触摸屏事件派发机制详解与源码分析一(View篇)

Android触摸屏事件派发机制详解与源码分析二(ViewGroup篇)

接下来通过code来看看具体的传递过程。

在布局文件中定义个container

<FrameLayout        android:id="@+id/container"        android:layout_width="match_parent"        android:layout_height="match_parent" />

自定义一些ViewGroup和View，重写一些和事件相关的方法。

public class TouchViewGroup2 extends LinearLayout{    public static final String TAG = "TouchEvent";    public TouchViewGroup2(Context context) {        super(context);        ViewGroup.LayoutParams vl = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);        setLayoutParams(vl);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_CANCEL");                break;        }        return super.onTouchEvent(event);    }    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_CANCEL");                break;        }        return super.onInterceptTouchEvent(ev);    }    @Override    public boolean dispatchTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchViewGroup2 dispatchTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchViewGroup2 dispatchTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchViewGroup2 dispatchTouchEvent action:ACTION_CANCEL");                break;        }        return super.dispatchTouchEvent(ev);    }}

public class TouchViewGroup extends LinearLayout {    public static final String TAG = "TouchEvent";    public TouchViewGroup(Context context) {        super(context);        ViewGroup.LayoutParams vl = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);        setLayoutParams(vl);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchViewGroup onTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchViewGroup onTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchViewGroup onTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchViewGroup onTouchEvent action:ACTION_CANCEL");                break;        }        return super.onTouchEvent(event);    }    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchViewGroup onInterceptTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchViewGroup onInterceptTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchViewGroup onInterceptTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchViewGroup onInterceptTouchEvent action:ACTION_CANCEL");                break;        }        return super.onInterceptTouchEvent(ev);    }    @Override    public boolean dispatchTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchViewGroup dispatchTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchViewGroup dispatchTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchViewGroup dispatchTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchViewGroup dispatchTouchEvent action:ACTION_CANCEL");                break;        }        return super.dispatchTouchEvent(ev);    }}

public class TouchView extends View {    public static final String TAG = "TouchEvent";    public TouchView(Context context) {        super(context);        ViewGroup.LayoutParams vl = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);        setLayoutParams(vl);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_CANCEL");                break;        }        return super.onTouchEvent(event);    }    @Override    public boolean dispatchTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchView dispatchTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchView dispatchTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchView dispatchTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchView dispatchTouchEvent action:ACTION_CANCEL");                break;        }        return super.dispatchTouchEvent(event);    }}

在Activity的onCreate方法中给container添加相应的ViewGroup和View。

ViewGroup vg = (ViewGroup)findViewById(R.id.container);ViewGroup vg1 = new TouchViewGroup(this);ViewGroup vg2 = new TouchViewGroup2(this);View v1 = new TouchView(this);vg.addView(vg1);vg1.addView(vg2);vg2.addView(v1);

在TouchView上滑动一下,查看一些log输出。

上面的code不做任何修改。输出下面的log

D/TouchEvent(19634): TouchViewGroup dispatchTouchEvent action:ACTION_DOWND/TouchEvent(19634): TouchViewGroup onInterceptTouchEvent action:ACTION_DOWND/TouchEvent(19634): TouchViewGroup2 dispatchTouchEvent action:ACTION_DOWND/TouchEvent(19634): TouchViewGroup2 onInterceptTouchEvent action:ACTION_DOWND/TouchEvent(19634): TouchView dispatchTouchEvent action:ACTION_DOWND/TouchEvent(19634): TouchView onTouchEvent action:ACTION_DOWND/TouchEvent(19634): TouchViewGroup2 onTouchEvent action:ACTION_DOWND/TouchEvent(19634): TouchViewGroup onTouchEvent action:ACTION_DOWN

我们发现，只输出了ACTION_DOWN事件。因为TouchViewGroup、TouchViewGroup2和TouchView的相应方法都返回的是false，导致没有相应view消费此次事件，所以这个事件“消失”了。

将TouchView的onTouchEvent返回值改为true。

@Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_CANCEL");                break;        }        //return super.onTouchEvent(event);        return true;    }

输出log：

D/TouchEvent(21567): TouchViewGroup dispatchTouchEvent action:ACTION_DOWND/TouchEvent(21567): TouchViewGroup onInterceptTouchEvent action:ACTION_DOWND/TouchEvent(21567): TouchViewGroup2 dispatchTouchEvent action:ACTION_DOWND/TouchEvent(21567): TouchViewGroup2 onInterceptTouchEvent action:ACTION_DOWND/TouchEvent(21567): TouchView dispatchTouchEvent action:ACTION_DOWND/TouchEvent(21567): TouchView onTouchEvent action:ACTION_DOWND/TouchEvent(21567): TouchViewGroup dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup2 onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchView dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchView onTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup2 onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchView dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchView onTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup2 onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchView dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchView onTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup2 onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchView dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchView onTouchEvent action:ACTION_MOVED/TouchEvent(21567): TouchViewGroup dispatchTouchEvent action:ACTION_UPD/TouchEvent(21567): TouchViewGroup onInterceptTouchEvent action:ACTION_UPD/TouchEvent(21567): TouchViewGroup2 dispatchTouchEvent action:ACTION_UPD/TouchEvent(21567): TouchViewGroup2 onInterceptTouchEvent action:ACTION_UPD/TouchEvent(21567): TouchView dispatchTouchEvent action:ACTION_UPD/TouchEvent(21567): TouchView onTouchEvent action:ACTION_UP

将TouchViewGroup2的onInterceptTouchEvent和onTouchEvent返回值改为true。

 @Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_CANCEL");                break;        }        //return super.onTouchEvent(event);        return true;    }    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_CANCEL");                break;        }        //return super.onInterceptTouchEvent(ev);        return true;    }

输出log：

D/TouchEvent(21964): TouchViewGroup dispatchTouchEvent action:ACTION_DOWND/TouchEvent(21964): TouchViewGroup onInterceptTouchEvent action:ACTION_DOWND/TouchEvent(21964): TouchViewGroup2 dispatchTouchEvent action:ACTION_DOWND/TouchEvent(21964): TouchViewGroup2 onInterceptTouchEvent action:ACTION_DOWND/TouchEvent(21964): TouchViewGroup2 onTouchEvent action:ACTION_DOWND/TouchEvent(21964): TouchViewGroup dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup2 onTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup2 onTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup2 onTouchEvent action:ACTION_MOVED/TouchEvent(21964): TouchViewGroup dispatchTouchEvent action:ACTION_UPD/TouchEvent(21964): TouchViewGroup onInterceptTouchEvent action:ACTION_UPD/TouchEvent(21964): TouchViewGroup2 dispatchTouchEvent action:ACTION_UPD/TouchEvent(21964): TouchViewGroup2 onTouchEvent action:ACTION_UP

我们发现TouchViewGroup2的onInterceptTouchEvent只在第一次ACTION_DOWN时调用了，之后都没有调用。

修改TouchView的onTouchEvent和TouchViewGroup2的onTouchEvent onInterceptTouchEvent方法。

@Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchView onTouchEvent action:ACTION_CANCEL");                break;        }        //return super.onTouchEvent(event);        return true;    }

 @Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchViewGroup2 onTouchEvent action:ACTION_CANCEL");                break;        }        //return super.onTouchEvent(event);        return true;    }    private int count = 0;    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_UP");                break;            case MotionEvent.ACTION_CANCEL:                Log.d(TAG, "TouchViewGroup2 onInterceptTouchEvent action:ACTION_CANCEL");                break;        }        count++;        if (count == 3) {            return true;        }        return super.onInterceptTouchEvent(ev);    }

输出log：

D/TouchEvent(22817): TouchViewGroup dispatchTouchEvent action:ACTION_DOWND/TouchEvent(22817): TouchViewGroup onInterceptTouchEvent action:ACTION_DOWND/TouchEvent(22817): TouchViewGroup2 dispatchTouchEvent action:ACTION_DOWND/TouchEvent(22817): TouchViewGroup2 onInterceptTouchEvent action:ACTION_DOWND/TouchEvent(22817): TouchView dispatchTouchEvent action:ACTION_DOWND/TouchEvent(22817): TouchView onTouchEvent action:ACTION_DOWND/TouchEvent(22817): TouchViewGroup dispatchTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup2 onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchView dispatchTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchView onTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup dispatchTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup2 onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchView dispatchTouchEvent action:ACTION_CANCELD/TouchEvent(22817): TouchView onTouchEvent action:ACTION_CANCELD/TouchEvent(22817): TouchViewGroup dispatchTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup onInterceptTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup2 dispatchTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup2 onTouchEvent action:ACTION_MOVED/TouchEvent(22817): TouchViewGroup dispatchTouchEvent action:ACTION_UPD/TouchEvent(22817): TouchViewGroup onInterceptTouchEvent action:ACTION_UPD/TouchEvent(22817): TouchViewGroup2 dispatchTouchEvent action:ACTION_UPD/TouchEvent(22817): TouchViewGroup2 onTouchEvent action:ACTION_UP

从log中可以看出，前两次的事件都是交付给TouchView的onTouchEvent处理。第三次由于TouchViewGroup2的onInterceptTouchEvent返回值为true，所以就向TouchView发送了ACTION_CANCEL事件。之后的事件都是传给了TouchViewGroup2的onTouchEvent处理。

暂时就先分析到这里。

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