// 獲取手指的索引    
int pointerIndex = motionEvent.getActionIndex();
// 通過手指索引獲取手指ID
int pointerId = motionEvent.getPointerId(pointerIndex);

        // 獲取手指索引
        int pointerIndex = event.getActionIndex();
        // 獲取坐標(biāo)值
        float x = event.getX(pointerIndex);
        float y = event.getY(pointerIndex);

case MotionEvent.ACTION_MOVE:
    // 根據(jù)PointerId獲取某個(gè)手指的索引    
    int pointerIndex = event.findPointerIndex(mPrimaryPointerId);
    // 獲取坐標(biāo)值
    float x = event.getX(pointerIndex);
    float y = event.getY(pointerIndex);
    break;

    public boolean onInterceptTouchEvent(MotionEvent ev) {
        switch (ev.getActionMasked()) {
            case MotionEvent.ACTION_DOWN:
                onPrimaryPointerDown(ev);
                break;
            case MotionEvent.ACTION_POINTER_DOWN:
                onPrimaryPointerDown(ev);
                break;
        }
        return super.onInterceptTouchEvent(ev);
    }
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getActionMasked()) {
            case MotionEvent.ACTION_POINTER_DOWN:
                onPrimaryPointerDown(event);
                break;
        }
        return true;
    }
    /**
     * 當(dāng)有新手指按下的時(shí)候，就認(rèn)作是主手指，于是重新記錄按下點(diǎn)的坐標(biāo)，以及更新最新的X坐標(biāo)。
     *
     * @param event 觸摸事件。
     */
    private void onPrimaryPointerDown(MotionEvent event) {
        // 獲取手指索引
        int pointerIndex = event.getActionIndex();
        // 通過手指索引獲取手指ID
        mPrimaryPointerId = event.getPointerId(pointerIndex);
        // 通過手指索引保存坐標(biāo)值
        mLastX = mStartX = event.getX(pointerIndex);
        mStartY = event.getY(pointerIndex);
    }    

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        switch (ev.getActionMasked()) {
            case MotionEvent.ACTION_POINTER_UP:
                onPrimaryPointerUp(ev);
                break;
        }
        return super.onInterceptTouchEvent(ev);
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getActionMasked()) {
            case MotionEvent.ACTION_POINTER_UP:
                onPrimaryPointerUp(event);
                break;
        }
        return true;
    }
    /**
     * 當(dāng)主手指抬起時(shí)，尋找一個(gè)新的主手指，并且更新最新的X坐標(biāo)值為新主手指的X坐標(biāo)值。
     *
     * @param event
     */
    private void onPrimaryPointerUp(MotionEvent event) {
        // 獲取抬起手指的索引值
        int pointerIndex = event.getActionIndex();
        // 通過索引值，獲取抬起手指的ID
        int pointerId = event.getPointerId(pointerIndex);
        // 如果抬起手指的ID等于主手指的ID
        if (pointerId == mPrimaryPointerId) {
            // 尋找一個(gè)已經(jīng)存在的手指索引
            final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
            // 通過新的手指索引獲取手指ID
            mPrimaryPointerId = event.getPointerId(newPointerIndex);
            // 通過新的手指索引獲取坐標(biāo)值
            mLastX = event.getX(newPointerIndex);
        }
    }    

    public boolean onInterceptTouchEvent(MotionEvent ev) {
        switch (ev.getActionMasked()) {
            case MotionEvent.ACTION_MOVE:
                // 獲取主手指的坐標(biāo)值
                PointF primaryPointerPoint = getPrimaryPointerPoint(ev);
                // 根據(jù)坐標(biāo)值判斷是否需要滑動(dòng)
                if (canScroll(primaryPointerPoint.x, primaryPointerPoint.y)) {
                    mBeingDragged = true;
                    getParent().requestDisallowInterceptTouchEvent(true);
                    // 執(zhí)行一次滑動(dòng)
                    performDrag(primaryPointerPoint.x);
                    mLastX = primaryPointerPoint.x;
                    // 可以滑動(dòng)就截?cái)嗍录?
                    return true;
                }
                break;
        }
        return super.onInterceptTouchEvent(ev);
    }
    /**
     * 獲取主手指在某個(gè)事件觸發(fā)時(shí)的坐標(biāo)。
     *
     * @param event 觸摸事件。
     * @return 如果成功，返回坐標(biāo)點(diǎn)，否則返回null。
     */
    private PointF getPrimaryPointerPoint(MotionEvent event) {
        PointF pointF = null;
        if (mPrimaryPointerId != INVALID_POINTER_ID) {
            int pointerIndex = event.findPointerIndex(mPrimaryPointerId);
            if (pointerIndex != -1) {
                pointF = new PointF(event.getX(pointerIndex), event.getY(pointerIndex));
            }
        }
        return pointF;
    }