你真的理解android事件分发机制了吗

最近在看一些源代码的时候，又遇到了android的事件分发机制，以前我以为我懂了，但是看着看着又糊涂了，于上浏览了下别人写的文章，越看越糊涂，干脆自己写个程序验证下，这一验证，才发现以前没有真正懂这个流程，今天我就用事实说话，来跟大家一起验证下android的事件分发机制（很多坑需要注意）：
事件分发中我们无非会遇到这么几个函数，dispatchTouchEvent，onInterceptTouchEvent，onTouchEvent，onTouch，onClick，onLongClick，先从一个简单的View说起，然后再给这个View外面嵌套一个ViewGroup：
一先看一个简单的View：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.fq.myviewgroup.MainActivity">    <com.fq.myviewgroup.MyTestView  android:layout_width="match_parent" android:layout_height="200dp" android:text="Hello World!" android:layout_gravity="center" android:gravity="center" android:background="#123321"/></LinearLayout>

package com.fq.myviewgroup;import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.view.MotionEvent;import android.view.View;import android.widget.TextView;/** * Created by fq on 2016/9/21. */public class MyTestView extends TextView implements View.OnClickListener,View.OnLongClickListener,View.OnTouchListener{    public static final String TAG = "fuqiang";    public MyTestView(Context context, AttributeSet attrs) {        super(context, attrs);        Log.e(TAG, "MyTestView");        setOnClickListener(this);        setOnLongClickListener(this);        setOnTouchListener(this);    }    @Override    public void onClick(View v) {        Log.e(TAG,"MyTestView ---onClick");    }    @Override    public boolean onLongClick(View v) {        Log.e(TAG,"MyTestView ---onLongClick");        return false;    }    @Override    public boolean dispatchTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyTestView ---dispatchTouchEvent -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyTestView ---dispatchTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyTestView ---dispatchTouchEvent -- ACTION_UP");                break;        }        return super.dispatchTouchEvent(event);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyTestView ---onTouchEvent -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyTestView ---onTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyTestView ---onTouchEvent -- ACTION_UP");                break;        }       return super.onTouchEvent(event);    }    @Override    public boolean onTouch(View v, MotionEvent event) {        int action = event.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyTestView ---onTouch -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyTestView ---onTouch -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyTestView ---onTouch -- ACTION_UP");                break;        }        return false;    }}

好了，程序很简单，在各个touch函数打印了相关log，下面我们先来做第一个操作，点击TextView，长按，然后松开，执行结果如下：

E/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---onTouch -- ACTION_DOWNE/fuqiang: MyTestView ---onTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---onLongClickE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_UPE/fuqiang: MyTestView ---onTouch -- ACTION_UPE/fuqiang: MyTestView ---onTouchEvent -- ACTION_UPE/fuqiang: MyTestView ---onClick

以此执行了dispatchTouchEvent，onTouch，onTouchEvent ，onLongClick，onClick，这里我们要注意
onTouch是在onTouchEvent 前执行的，然后执行了长按onLongClick，最后当手抬起的时候，才会执行onClick。
接下来我们第二个操作，点击TextView，移动，然后松开：

E/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---onTouch -- ACTION_DOWNE/fuqiang: MyTestView ---onTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_UPE/fuqiang: MyTestView ---onTouch -- ACTION_UPE/fuqiang: MyTestView ---onTouchEvent -- ACTION_UPE/fuqiang: MyTestView ---onClick

也很清晰，只是长按没有了而已，接下来我们对代码进行一些改动，让onTouch返回true：

 @Override    public boolean onTouch(View v, MotionEvent event) {        int action = event.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyTestView ---onTouch -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyTestView ---onTouch -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyTestView ---onTouch -- ACTION_UP");                break;        }        return true;    }

接下来点击，移动，松开：

E/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---onTouch -- ACTION_DOWNE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_UPE/fuqiang: MyTestView ---onTouch -- ACTION_UP

可以看到onTouchEvent 没有被执行了，这是为什么呢，看下dispatchTouchEvent 的源码：

ListenerInfo li = mListenerInfo;            if (li != null && li.mOnTouchListener != null                    && (mViewFlags & ENABLED_MASK) == ENABLED                    && li.mOnTouchListener.onTouch(this, event)) {                result = true;            }            if (!result && onTouchEvent(event)) {                result = true;            }

如果onTouch的返回值是true，直接返回了，不继续执行onTouchEvent了。
看另外一个坑，现在把如下代码注释掉：

//        setOnClickListener(this);//        setOnLongClickListener(this);

再次按下，移动，松开：

E/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---onTouch -- ACTION_DOWNE/fuqiang: MyTestView ---onTouchEvent -- ACTION_DOWN

移动和抬起全都没有监听到了，这是为什么呢，查看源码发现，设置上面这两句会使onTouchEvent的返回值为true，onTouchEvent的返回值为true才会消费接下来的一系列事件，如果是默认（false），是不会继续消费移动和抬起事件的。

好了，接下来我给这个TextView外面再套一层我写的ViewGroup，代码如下：

<?xml version="1.0" encoding="utf-8"?><com.fq.myviewgroup.MyLinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.fq.myviewgroup.MainActivity">    <com.fq.myviewgroup.MyTestView        android:layout_width="match_parent"        android:layout_height="200dp"        android:text="Hello World!"        android:layout_gravity="center"        android:gravity="center"        android:background="#123321"/></com.fq.myviewgroup.MyLinearLayout>

package com.fq.myviewgroup;import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.view.MotionEvent;import android.view.View;import android.widget.LinearLayout;/** * Created by fq on 2016/9/21. */public class MyLinearLayout extends LinearLayout implements View.OnClickListener,View.OnLongClickListener,View.OnTouchListener{    public static final String TAG = "fuqiang";    public MyLinearLayout(Context context, AttributeSet attrs) {        super(context, attrs);        Log.e(TAG , "MyLinearLayout");// setOnClickListener(this);// setOnLongClickListener(this);          setOnTouchListener(this);    }    @Override    public void onClick(View v) {        Log.e(TAG,"MyLinearLayout ---onClick");    }    @Override    public boolean onLongClick(View v) {        Log.e(TAG,"MyLinearLayout ---onLongClick");        return false;    }    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyLinearLayout ---onInterceptTouchEvent -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyLinearLayout ---onInterceptTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyLinearLayout ---onInterceptTouchEvent -- ACTION_UP");                break;        }        return super.onInterceptTouchEvent(ev);    }    @Override    public boolean dispatchTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyLinearLayout ---dispatchTouchEvent -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyLinearLayout ---dispatchTouchEvent -- ACTION_UP");                break;        }        return super.dispatchTouchEvent(ev);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyLinearLayout ---onTouchEvent -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyLinearLayout ---onTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyLinearLayout ---onTouchEvent -- ACTION_UP");                break;        }        return super.onTouchEvent(event);    }    @Override    public boolean onTouch(View v, MotionEvent event) {        int action = event.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyLinearLayout ---onTouch -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyLinearLayout ---onTouch -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyLinearLayout ---onTouch -- ACTION_UP");                break;        }        return false;    }    @Override    public void requestDisallowInterceptTouchEvent(boolean disallowIntercept)    {        Log.e(TAG, "requestDisallowInterceptTouchEvent ");        super.requestDisallowInterceptTouchEvent(disallowIntercept);    }}

也很简单，就是打印了关键函数的一些log，onClick和onLongClick刚才分析过了，这里直接注释掉，不解释了，接下来，我依然在TextView这个区域按下，移动，抬起，执行结果如下：

E/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---onTouch -- ACTION_DOWNE/fuqiang: MyTestView ---onTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onTouch -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_DOWN

执行次序，父类的dispatchTouchEvent ，onInterceptTouchEvent ，子类的dispatchTouchEvent ，onTouch ，onTouchEvent ，然后又重新回到父类的onTouch ，onTouchEvent ，并且只监听了ACTION_DOWN，移动和抬起事件没人管了，这是为什么，因为无论是父类还是子类，onTouchEvent 默认都返回的false，也就是说都不管接下来发生的事，按下事件从父类传到子类，又从子类传到父类，没人愿意管，好，下面我们修改父类的onTouchEvent ，让它返回true：

@Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyLinearLayout ---onTouchEvent -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyLinearLayout ---onTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyLinearLayout ---onTouchEvent -- ACTION_UP");                break;        }        return true;    }

然后再按下，移动，抬起，执行结果：

E/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---onTouch -- ACTION_DOWNE/fuqiang: MyTestView ---onTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onTouch -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_UPE/fuqiang: MyLinearLayout ---onTouch -- ACTION_UPE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_UP

可以看到先执行父类的dispatchTouchEvent ，onInterceptTouchEvent ，然后传到子类，发现子类的onTouchEvent 返回false，表示他不打算管，然后又传回给父类onTouchEvent ，父类onTouchEvent 返回true了，表示要管，所以接下来的移动和抬起事件都传递给父类的dispatchTouchEvent ，onTouch ，onTouchEvent 方法，这时不会再传递给onInterceptTouchEvent ，onInterceptTouchEvent 只负责对子类的分发。
接下来我把子类的onTouchEvent返回值改成True：

@Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyTestView ---onTouchEvent -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyTestView ---onTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyTestView ---onTouchEvent -- ACTION_UP");                break;        }       return true;    }

然后，按下，移动，抬起：

E/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---onTouch -- ACTION_DOWNE/fuqiang: MyTestView ---onTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_UPE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_UPE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_UPE/fuqiang: MyTestView ---onTouch -- ACTION_UPE/fuqiang: MyTestView ---onTouchEvent -- ACTION_UP

可以看到子类消费了接下来的事件，onInterceptTouchEvent 每次还会执行，因为是对子类的分发，最后执行完并不会再回到父类，因为自己已经把剩余事件给消费了。
接下来我们代码不动，进行另外一种操作，我在TextView之外的区域，点击，移动，抬起，执行结果如下：

E/fuqiang: MyLinearLayoutE/fuqiang: MyTestViewE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onTouch -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_UPE/fuqiang: MyLinearLayout ---onTouch -- ACTION_UPE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_UP

可以看到，并没有分发给子类，而是自己消费了，是因为按下的区域并没有找到子View，那如果我把父类的onTouchEvent返回值改成默认呢？：

@Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyLinearLayout ---onTouchEvent -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyLinearLayout ---onTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyLinearLayout ---onTouchEvent -- ACTION_UP");                break;        }        return super.onTouchEvent(event);    }

在同样在TextView之外的区域按下，移动，抬起

E/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onTouch -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_DOWN

由于这个父类onTouchEvent返回值是默认（false），他不打算管接下来的事件，所以就只监听到Down事件了。
接下来我来修改onInterceptTouchEvent，让ACTION_DOWN的时候直接返回true：

 @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyLinearLayout ---onInterceptTouchEvent -- ACTION_DOWN");                return true;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyLinearLayout ---onInterceptTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyLinearLayout ---onInterceptTouchEvent -- ACTION_UP");                break;        }        return super.onInterceptTouchEvent(ev);    }

然后在TextView所在区域按下，移动，抬起：

E/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onTouch -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_UPE/fuqiang: MyLinearLayout ---onTouch -- ACTION_UPE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_UP

可以看到，父类拦截了接下来的所有操作，并没有传递给子类，我们如果想让父类拦截，在onInterceptTouchEvent按下，移动和抬起事件返回true即可，但是如果明明被拦截了，子类依然想执行怎么办，getParent().requestDisallowInterceptTouchEvent(true)，这样调用即可，之前父类的拦截就失效了，但是只能在onInterceptTouchEvent的移动事件ACTION_MOVE之后返回true才行，在ACTION_DOWN里返回true，子类这样写不起作用：

@Override    public boolean dispatchTouchEvent(MotionEvent event) {        int action = event.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                getParent().requestDisallowInterceptTouchEvent(true);                Log.e(TAG,"MyTestView ---dispatchTouchEvent -- ACTION_DOWN");                break;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyTestView ---dispatchTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                getParent().requestDisallowInterceptTouchEvent(false);                Log.e(TAG,"MyTestView ---dispatchTouchEvent -- ACTION_UP");                break;        }        return super.dispatchTouchEvent(event);    }

再按下，移动，抬起，如下：

E/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---onInterceptTouchEvent -- ACTION_DOWNE/fuqiang: requestDisallowInterceptTouchEvent E/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyTestView ---onTouch -- ACTION_DOWNE/fuqiang: MyTestView ---onTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyTestView ---onTouch -- ACTION_MOVEE/fuqiang: MyTestView ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_UPE/fuqiang: requestDisallowInterceptTouchEvent E/fuqiang: MyTestView ---dispatchTouchEvent -- ACTION_UPE/fuqiang: MyTestView ---onTouch -- ACTION_UPE/fuqiang: MyTestView ---onTouchEvent -- ACTION_UP

我们看到父类的拦截不起作用了，子类仍然可以监听到后续的操作。

来说最后一个，如果我在父类的dispatchTouchEvent里返回true会怎么样呢：

public boolean dispatchTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action){            case MotionEvent.ACTION_DOWN:                Log.e(TAG,"MyLinearLayout ---dispatchTouchEvent -- ACTION_DOWN");                return true;            case MotionEvent.ACTION_MOVE:                Log.e(TAG,"MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVE");                break;            case MotionEvent.ACTION_UP:                Log.e(TAG,"MyLinearLayout ---dispatchTouchEvent -- ACTION_UP");                break;        }        return super.dispatchTouchEvent(ev);    }

在case MotionEvent.ACTION_DOWN:的时候返回了true，依然是按下，移动，抬起：

E/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_DOWNE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouch -- ACTION_MOVEE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_MOVEE/fuqiang: MyLinearLayout ---dispatchTouchEvent -- ACTION_UPE/fuqiang: MyLinearLayout ---onTouch -- ACTION_UPE/fuqiang: MyLinearLayout ---onTouchEvent -- ACTION_UP

可以看到dispatchTouchEvent 监听完DOWN之后，DOWN就此结束了，onInterceptTouchEvent 和onTouch ，onTouchEvent 都没有监听Down了，并且后续的移动和抬起onInterceptTouchEvent 也不执行了，而是父类的dispatchTouchEvent ，onTouch ，onTouchEvent 依次执行。

好了，android事件分发机制就聊到这里，有人会说你为什么不从源码角度去分析下，我想说的是这个东西本来就很多坑了，你这个时候记住了，用的时候可能又会忘了，知道怎么用就好，再分析下源码，估计头更大了，如有问题，欢迎指正，谢谢。

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