Android ViewGroup事件分发有这一篇就够了

写这一篇文章之前我看了好多遍事件分发机制的流程，并且来自不同的书籍，但始终无法记住事件分发流程。

于是我写了一个demo分析事件分发的流程，目的为了找到事件分发机制的规律方便记忆。

以下是总结的规律，如果错误请及时举报，说到底有些东西还得亲手试试才能弄明白

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规律：

dispatchTouchEvent.   

true 不在向下一级view分发事件,停止

false 向上Activity的onTouchEvent

执行super方法 向同一个View的onInterceptTouchEvent或者onTouchEvent传递或者下一个View的dispatchTouchEvent传递

 

onInterceptTouchEvent

true 表示拦截，执行该View的onTouchEvent 

false 和执行super方法表示不拦截执行下一个view的dispatchTouchEvent

 

onTouchEvent

true 和super 消费此事件 

false 把事件抛向Activity onTouchEvent

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流程图

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代码示例：

public class MyTextView extends android.support.v7.widget.AppCompatTextView {

    private static final String TAG = "MyTextView";

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

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

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

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        Log.d(TAG,"dispatchTouchEvent");
        return true;
        //return super.dispatchTouchEvent(event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Log.d(TAG,"onTouchEvent");
        //return true;
        return super.onTouchEvent(event);
    }
}

public class MyLinearLayout extends LinearLayout {

    private static final String TAG = "MyLinearLayout";

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

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

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

    public MyLinearLayout(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        Log.d(TAG,"dispatchTouchEvent");
        //return false;
        return super.dispatchTouchEvent(ev);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        Log.d(TAG,"onInterceptTouchEvent");
        return super.onInterceptTouchEvent(ev);
        //return true;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Log.d(TAG,"onTouchEvent");
        return super.onTouchEvent(event);
    }
}

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView textView = findViewById(R.id.mytextview);
        textView.setOnClickListener(this);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        Log.d("MainActivity","dispatchTouchEvent");
        //return false;
        return super.dispatchTouchEvent(ev);
    }

    @Override
    public void onUserInteraction() {
        //Log.d("MainActivity","onUserInteraction");
        //return true;
        super.onUserInteraction();
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Log.d("MainActivity","onTouchEvent");
        //return true;
        return super.onTouchEvent(event);
    }

    @Override
    public void onClick(View v) {
        Log.d("MainActivity","onClick");
    }
}