android 事件分发

android事件分发默认流程

主要函数
dispatchTouchEvent
onInterceptTouchEvent
onTouchEvent

• 事件传递流程
  

activity—->viewgroup—->view—-> viewgroup—-> activity—-over
如下图

分发总结

事件分发的方法都会返回boolean值,有三种状态 super. true false
activity dispatchTouchEvent返回false会直接走activity的onTouchEvent 然后结束

1.返回super. 就是默认分发顺序 如上图;
2.返回true时很好理解 就是本次事件被消费掉了(onInterceptTouchEvent除外) ,意思就是没有了 不会再继续传递;
3.返回false ,view总dispatchTouchEvent 返回false拦截不会向下分发会直接回调上级控件(viewgroup)的onTouchEvent ,接下来跟正常流程走.viewgroup dispatchTouchEvent的返回false会回调activity的onTouchEvent;
4.viewgroup的onInterceptTouchEvent函数比较特殊,返回true会直接掉自己的onTouchEvent返回false的话会走正常分发流程;

代码验证

- ---- viewgroup
public class MLinearlayout extends LinearLayout{

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

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


    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {

        Log.i("MLinearlayout","onInterceptTouchEvent");
        return false;
//        return super.onInterceptTouchEvent(ev);


    }


    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {

        Log.i("MLinearlayout","dispatchTouchEvent");
//        return true;
        return super.dispatchTouchEvent(ev);
    }


    @Override
    public boolean onTouchEvent(MotionEvent event) {

        Log.i("MLinearlayout","onTouchEvent");
        return super.onTouchEvent(event);


    }


}
/**
 * @author luki
 * @create 2018/4/19 下午2:20
 * @function :
 */

-----view

public class MImage extends AppCompatImageView {


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

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



    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {

        Log.i("MImage--------","dispatchTouchEvent");
//        return false;
        return super.dispatchTouchEvent(ev);
    }


    @Override
    public boolean onTouchEvent(MotionEvent event) {

        Log.i("MImage--------","onTouchEvent");
        return super.onTouchEvent(event);


    }

}
--------activity
"1.0" encoding="utf-8"?>
"http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorPrimary"
    android:orientation="vertical"
    android:padding="10dp">


    "@+id/m_linear"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/khaki"
        android:gravity="center"
        android:orientation="vertical">

        "@+id/btn_i"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="我是一个按钮" />


        "@+id/m_imag"
            android:layout_width="300dp"
            android:layout_height="100dp"
            android:scaleType="fitXY"
            android:src="@mipmap/ic_launcher" />


    






/**
 * @author luki
 * @create 2018/2/28 下午5:17
 * @function :
 */

public class ActionTestActivity extends AppCompatActivity {


    @BindView(R.id.btn_i)
    Button btnI;
    @BindView(R.id.m_linear)
    MLinearlayout mLinear;
    @BindView(R.id.m_imag)
    MImage m_imag;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_aciton);
        ButterKnife.bind(this);

        initData();

    }


    public void initData() {

        mLinear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Log.i("MLinearlayout","OnClickListener");

            }
        });

        mLinear.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                Log.i("MLinearlayout","setOnTouchListener");
                return false;
            }
        });

//        btnI.setOnClickListener(new View.OnClickListener() {
//            @Override
//            public void onClick(View v) {
//                Log.i("btn onClick","OnClickListener");
//            }
//        });
//
//        m_imag.setOnClickListener(new View.OnClickListener() {
//            @Override
//            public void onClick(View v) {
//                Log.i("m_imag onClick","OnClickListener");
//            }
//        });
    }

补充一点viewgroup view 如果设置onTouch 事件 onTouch的回调会在onTouchEvent之前 原理可以去看 dispatchTouchEvent 方法的源码 他们调用 有先后顺序;