android觸摸事件傳遞機制

一次完整的事件傳遞主要包括三個階段：事件的分發、攔截、消費。
1.分發（Dispatch）：事件的分發對應着dispatchTouchEvent方法

public boolean dispatchTouchEvent(MotionEvent event)

2.攔截（Intercept）:事件的攔截對應着onInterceptTouchEvent方法，這個方法只在ViewGroup及其子類中才存在，在View和Activity中是不存在的
3.消費（Consume）:事件的消費對應着onThouchEvent方法

public boolean onTouchEvent(MotionEvent event)

在Android系統中，擁有事件傳遞處理能力的類有以下三種，
1.Activity：擁有dispatchThouchEvent和onThouchEvent兩個方法
2.ViewGroup: 擁有dispatchThouchEvent、onInterceptTouchEvent和onThouchEvent三個方法
3.View:擁有dispatchThouchEvent和onThouchEvent兩個方法。
來個事例代碼：

public class MyTextView extends AppCompatTextView {
    private String TAG = "MyTextView";

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

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

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


    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        switch (event.getAction()) {

            case MotionEvent.ACTION_DOWN:
                Log.e(TAG,"dispatchTouchEvent_ACTION_DOWN");
                break;
            case MotionEvent.ACTION_MOVE:
                Log.e(TAG,"dispatchTouchEvent_ACTION_MOVE");
                break;
            case MotionEvent.ACTION_UP:
                Log.e(TAG,"dispatchTouchEvent_ACTION_UP");
                break;
            case MotionEvent.ACTION_CANCEL:
                Log.e(TAG,"dispatchTouchEvent_ACTION_CANCEL");
                break;

        }


        return super.dispatchTouchEvent(event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {



        switch (event.getAction()) {

            case MotionEvent.ACTION_DOWN:
                Log.e(TAG,"onTouchEvent_ACTION_DOWN");
                break;
            case MotionEvent.ACTION_MOVE:
                Log.e(TAG,"onTouchEvent_ACTION_MOVE");
                break;
            case MotionEvent.ACTION_UP:
                Log.e(TAG,"onTouchEvent_ACTION_UP");
                break;
            case MotionEvent.ACTION_CANCEL:
                Log.e(TAG,"onTouchEvent_ACTION_CANCEL");
                break;

        }

        return super.onTouchEvent(event);
    }
}

public class MainActivity extends AppCompatActivity {
    private String TAG = "MainActivity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        MyTextView viewById = (MyTextView) findViewById(R.id.mytextView);
        viewById.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.e(TAG, "MyTextView_Onclick");
            }
        });
        viewById.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {


                switch (event.getAction()) {

                    case MotionEvent.ACTION_DOWN:
                        Log.e(TAG, "MyTextView_onTouch_ACTION_DOWN");
                        break;
                    case MotionEvent.ACTION_MOVE:
                        Log.e(TAG, "MyTextView_onTouch_ACTION_MOVE");
                        break;
                    case MotionEvent.ACTION_UP:
                        Log.e(TAG, "MyTextView_onTouch_ACTION_UP");
                        break;
                    case MotionEvent.ACTION_CANCEL:
                        Log.e(TAG, "MyTextView_onTouch_ACTION_CANCEL");
                        break;

                }









                return false;
            }
        });
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        switch (event.getAction()) {

            case MotionEvent.ACTION_DOWN:
                Log.e(TAG, "dispatchTouchEvent_ACTION_DOWN");
                break;
            case MotionEvent.ACTION_MOVE:
                Log.e(TAG, "dispatchTouchEvent_ACTION_MOVE");
                break;
            case MotionEvent.ACTION_UP:
                Log.e(TAG, "dispatchTouchEvent_ACTION_UP");
                break;
            case MotionEvent.ACTION_CANCEL:
                Log.e(TAG, "dispatchTouchEvent_ACTION_CANCEL");
                break;

        }


        return super.dispatchTouchEvent(event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {


        switch (event.getAction()) {

            case MotionEvent.ACTION_DOWN:
                Log.e(TAG, "onTouchEvent_ACTION_DOWN");
                break;
            case MotionEvent.ACTION_MOVE:
                Log.e(TAG, "onTouchEvent_ACTION_MOVE");
                break;
            case MotionEvent.ACTION_UP:
                Log.e(TAG, "onTouchEvent_ACTION_UP");
                break;
            case MotionEvent.ACTION_CANCEL:
                Log.e(TAG, "onTouchEvent_ACTION_CANCEL");
                break;

        }

        return super.onTouchEvent(event);
    }

}

點擊控件打印如下：

看到打印的日誌得到如下圖