View的事件分发机制

 如果父类的onInterceptTouchEvent拦截了事件，子类可以通过requestDisallowInterceptTouchEvent(true)方法让父类不拦截该事件但是需要在子类监听onTouchListener监听到Action_Down事件之后再设置。并且父类不能拦截Action_Down事件。

因为ViewGroup在接收到Action_Down事件后，重置了请求不允许拦截的值

 

 子类接收到Action_Down事件之后可以请求父类不拦截点击事件。栗子如下：

/**
 * ViewGroup
 */

public class MyViewGroup extends LinearLayout{

    public MyViewGroup(Context context) {
        super(context);
    }

    public MyViewGroup(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public MyViewGroup(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        Log.i("嘻嘻","dispatchTouchEvent "+ev.getAction());
        return super.dispatchTouchEvent(ev);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        Log.i("嘻嘻","onInterceptTouchEvent "+ev.getAction());
        if(ev.getAction()==MotionEvent.ACTION_DOWN){
            return false;
        }
        return true;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Log.i("嘻嘻","onTouchEvent "+event.getAction());
        return false;
    }

}

<?xml version="1.0" encoding="utf-8"?>
<com.alipay.sdk.pay.demo.MyViewGroup xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"

    android:layout_height="match_parent"
    tools:context="com.alipay.sdk.pay.demo.TestActivity">

    <LinearLayout
        android:id="@+id/root_view"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:background="#f00"
        android:clickable="true"
        android:orientation="vertical"/>


</com.alipay.sdk.pay.demo.MyViewGroup>

public class TestActivity extends Activity {
    LinearLayout rootView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);
        rootView = findViewById(R.id.root_view);
        rootView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.i("嘻嘻", "哈哈哈  rootView  setOnClickListener ");
            }
        });
        rootView.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                Log.i("嘻嘻", "rootView onTouch " + event.getAction());
                switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        rootView.requestDisallowInterceptTouchEvent(true);
                        break;
                }
                return false;
            }
        });
    }
}